USDA United States - 

Department of 

Agriculture 

Forest Service 

Rocky Mountain 

Research Station 

General Technical Report 

RMRS-GTR-17 

September 1998 

,* - 

Vascular Plant Species of the 

Pawnee National Grassland 

Donald L. Hazlett 
Abstract 

Hazlett, Donald L. 1998. Vascular plant species of the pawnee National Grassland. General 

Technical Report RMRS-GTR-17. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station. 26 p. 

This report briefly describes the main vegetation types and lists the vascular plant species that are 

known to occur in and near the Pawnee National Grassland, Weld County, Colorado. A checklist 

includes the scientific and common names for 521 species. Of these, 1 15 plant species (22 percent) 

are not native to this region. The life forms, habitats, and geographic distribution of native and 

introduced plants are summarized and discussed. 

Keywords: grasslands, Colorado flora, Great Plains flora, plant lists 

The Author 

Dr. Donald L. Hazlett, a native of the eastern plains of Colorado, has lived and worked in the Pawnee 

National Grassland region since 1983. Before 1983 Don spent 12 years working in Honduras and 

Costa Rica. He has worked for Colorado State University as site manager for the Central Plains 

Experimental Range, as a visiting professor in the biology department, and as a plant taxonomist for 

the Center for Ecological Management of Military Lands. Since 1995 Don has been a research 

contractor for ecological and floristic studies in the western United States. He prefers ethnobotanical 

studies. 

Publisher 

Rocky Mountain Research Station 

Fort Collins, Colorado 

September 1 998 

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Rocky Mountain Research Station 

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Fort Collins, CO 80524-8597 

Cover photo of the Pawnee Buttes area by Donald L. Hazlett 
Vascular Plant Species of the 

Pawnee National Grassland 

Donald L. Hazlett 

Contents 

Introduction ...................................................................................................... 1 

Physical Setting ................................................................................................ 1 

Vegetation ......................................................................................................... 4 

Nomenclature ................................................................................................... 8 

Distribution ........................................................................................................ 8 

Literature Cited ............................................................................................... 1 1 

Checklist of Vascular Plant Species ................................................................ 14 

Acknowledgments 

The author gratefully acknowledges the valuable assistance of the following individuals in editing of this manuscript: Dr. Craig C. Freeman, associate curator of the Natural 

History Museum and Biodiversity Research Center, Lawrence, Kansas; Rick Brune, 

consultant and long-time student of the eastern plains flora; Bruce Bosley, county 

extension agent, Morgan County, Colorado; Janet Wingate, Denver Botanic Garden; 

Loraine Yeatts, botanist; and Dina Clark, University of Colorado, Boulder. Continual 

support for plant identifications has been provided by Burrell E. Nelson, herbarium 

manager, and Dr. Ronald Hartman, curator, of the Rocky Mountain Herbarium. I also 

thank Mark Ball and Maggie Marston, Pawnee National Grassland Office, for their 

continual support for floristic surveys. Maggie Marston created the map. Lane Eskew 

of the Rocky Mountain Research Station did an excellent job of editing this manuscript. 

Linda Joyce, Project Leader at the Station supported me throughout this project. 

Introduction 

This publication documents vascular plants that occur 

within the boundaries of an area that includes all of the 

Pawnee National Grassland. The list will be useful to 

biologists and anyone looking for a common or scientific 

name for a plant that occurs in the shortgrass steppe 

region of northeastern Colorado. No plant species checklist is complete. In this large survey area, the discovery of 

additional native plant species is very likely and new 

exotic plant species could invade and become established 

in this area. It should be easy to add two or three additional plant species to this checklist but difficult to add 20- 

30 species. 

The floristic survey area is in Weld County, Colorado, 

between 40" 36' and 41" 00' N latitude and between 103" 34' 

and 104" 48' E longitude (figure 1). The northern border of 

the study area is the Wyoming state line; the western 

border is Highway 85; the southern border is Weld County 

Road 86; and the eastern border is the Logan County line. 

This is about 1,728 square miles or 1,105,920 acres (447,566 

ha). The survey area is a rectangle of approximately 64 

miles (103 km) east to west and 27 miles (43 km) north to 

south. The highest elevation is about 6,350 feet (1,935 m) 

in the northwestern portion near the "Chalk Bluffs" and 

the lowest elevation is about 4,300 feet (1,310 m) in the 

southeastern portion around South Pawnee Creek. In 

general, the elevation of the Colorado Piedmont declines 

from the foothills of the mountains toward the east at a 

rate of about 10 feet per mile (2 m per km). 

The Pawnee National Grassland, administered by the 

USDA Forest Service, covers 193,060 acres (79,876 ha). 

These public grasslands occur in a mosaic pattern over the 

entire survey area and include portions of all habitat types 

that occur in the survey area. For this reason more than 95 

percent of the plant species on this checklist occur on the 

Pawnee National Grassland. The survey area includes the 

Central Plains Experimental Range (CPER), a research area 

administered by the Agricultural Research Service (figure 1). The CPER covers 14,639 acres (6,057 ha) andis about 

8 percent the size of the Pawnee National Grassland. 

- 

Physical Setting 

Climate 

Three important factors affect the climate of the survey 

area: continentality, air masses, and mountain barriers 

(Wilken 1987). Continentality refers to wide fluctuations 

in diurnal and seasonal temperatures that are characteristic of the central portions of continents. Midcontinental 

areas are far removed from the temperature-moderating 

effects of oceans or major bodies of water. The rapid 

absorption and release of heat by mid-continental land 

surfaces contributes to wide fluctuations in diurnal and 

seasonal temperatures. 

A second factor is the movement of large air masses 

across the Great Plains. These air masses usually have 

fairly uniform temperatures and relative humidities that 

are characteristic of their places of origin. Four main types 

of air masses that invade this section of the Great Plains 

are: (1) a continental tropical mass of warm, dry air from 

the southwest, (2) a continental polar mass of cold, dry air 

from Canada and northern states, (3) a marine tropical 

mass of warm, wet air from the Gulf of Mexico, and (4) a 

marine polar mass of cold, wet air from the northern 

Pacific Ocean and the Gulf of Alaska. 

The third factor that affects the climate in this area is the 

Rocky Mountains. The north-southorientation of theRocky 

Mountains places them perpendicular to the westerly 

winds that prevail at these latitudes. Therefore, the mountains partially block the invasions of marine polar air 

masses from the west. This feature, sometimes called the 

"rain shadow effect," contributes to drier conditions on the 

Great Plains east of the mountains and increasing precipitation as one moves east toward Kansas. In contrast, there 

are no large mountains to prevent the movement of warmwet air masses up from the south. Air masses that move 

north during the spring bring much of the annual precipitation. Hot, dry air masses from the southwest also invade 

during the summer months. Frigid, continental air masses 

from polar regions occasionally enter northeastern Colorado from the north during the winter. 

A significant geomorphology feature toward the north 

is the Wyoming ridge in the northwestern portion of the 

study area, located between the Pawnee National Grassland and the Wyoming border. This escarpment serves as 

a weak barrier to moisture-laden air masses that move 

toward the Pawnee National Grassland from the north. 

Crabb (1981) reported an average air temperature of 

29" F (-2" C) during the winter months in northeastern 

Colorado with an average daily minimum temperature of 

14" F (-10" C). For summer months the average air temperature for this region is 70" F (21" C), with an average 

daily maximum temperature of 87" F (31" C). The range in 

mean annual precipitation for the study area is 12-15 

inches (305-380 mm). A 21-year average annual precipitation at the Central Plains Experimental Range (1969-1989) 

was 12.6 inches or 320 mm/ y. 

The driest months in the study area are October to 

February, when the average monthly precipitation is less 

than one-half inch (12 mm). About 70 percent of the 

annual precipitation occurs between April and August, 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 1 
USDA Forest Service Gen. Tech. Rep. RMR-TR-17.1998 
the main growing season. The average date of the first fall 

frost is early October and for the last spring frost is about 

mid-May. Afternoon or evening thunderstorms during 

the growing season occur on an average of 41 days each 

year. Localized thunderstorms, sometimes only one or a 

few events, greatly increase summer rainfall amounts. For 

each summer month the average precipitation is about 

two inches (52-55 mm). Although long-term rainfall 

amounts for June, July, and August are similar, there is a 

high degree of spatial and temporal variation in summer 

rainfall amounts. The unpredictable and spotty occurrence of summer thunderstorms is reflected by the highest 

standard deviations in monthly precipitation amounts 

during June, July, and August. 

The average annual snowfall amount in northeastern 

Colorado is about 40 inches with an average of about 18 

days with an inch or more of snow on the ground (Crabb 

1981). Wind-driven snow often accumulates on leeward 

sides of hills and around shrubs. The meltdown of large 

patches of snow, especially in rocky or sandy soil, results 

in water penetration to greater depths at these locations. 

Geology 

The Pawnee National Grassland is located in the geomorphic sections of the Great Plains province known as 

the High Plains and the Colorado Piedmont (Trimble 

1993). The escarpments along the northern part of the 

study area are the northern border of the Colorado Piedmont. The Colorado Piedmont is a High Plains area where 

the original plain surfaces have eroded away. The High 

Plains are areas east of the Rocky Mountains that were a 

fluviate plain during the Tertiarv Period and that have 

since been exposed to minimal erosion. The Colorado 

Piedmont was part of an extensive alluvial area that 

extended east from the Rockv Mountains to beyond the 

eastern border of the Great Plains (Thornbury 1969). Surface materials that still exist between ancient stream channels toward the east were deposited during Tertiary sedimentation cycles (Lugn and Lugn 1956). Four main Tertiary sedimentation cycles (from oldest to most recent) 

were the White River (Oligocene Epoch), the Arikaree 

(lower Miocene), the Hemignord (Miocene), and the 

Ogallala (Miocene). The uppermost and most extensive of 

the Tertiary fluviate formations are sediments from the 

Ogallala formation. 

The Arikaree and the Ogallala sediments are well known 

to paleontologists because these layers often contain vertebrate fossils (Scott 1978). Vertebrate fossils discovered 

in these sediment layers include bones of three-toed horses, 

dwarf horses, rhinoceros, ancient swine, camels, vultures, 

cormorants, a hippopotamus-like animal, and others. 

In eastern Colorado these four layers of ancient sediments vary in thickness from a few feet to several hundred 

feet, depending upon the shape of topographic surfaces 

where they were deposited. Parts of the SouthPlatte River 

have eroded 1,500 to 2,000 feet downward into these 

sediments. Other wind-swept portions of Ogallala sediments have been pittedby solution and deflation and have 

then been refilled by sand and silt. Still other portions of 

the Ogallala sediments have been little modified for over 

5 million years. These ancient and uneroded land surfaces 

are noteworthy as a geological rarity. 

Two notable geomorphologic features in the study area 

are the Pawnee Buttes and the Chalk Bluffs. The Chalk 

Bluff escarpments are a series of ridges, steep hills, and 

siltstone rock outcrops often capped by sandstone. These 

escarpments, located on private land, are considered to be 

the northern boundary of the Colorado Piedmont. The 

best known geomorphological feature in the survey area 

is the Pawnee Buttes. These two buttes rise to 5,275 feet 

(1,608 m). The tops of the buttes are only about 250 feet 

above the plains surface, but because of their isolation, 

they are a well-known landmark. Sediments from the 

Ogallala formationcap the buttes, with White River Group 

sediments in the lower portions. They have avoided the 

erosive forces that lowered the sediment layers of the 

surrounding areas, probably due to a slightly thickened or 

erosion resistant cap rock (Rick Brune, consultant, personal communication 1998). 

Soils 

Most of the soils on the Pawnee National Grassland are 

shallow to deep loams that are well drained (Crabb 1981). 

Over most of the area is a loamy, wind-mixed veneer layer 

of soil of varying depths. These soils are underlain by a 

variable pattern of shale and sandstone parent materials. 

This surface "veneer" or uniform topsoil layer is a favorable substrate for blue grama grass. Rock or gravel areas 

of shale and sandstone can be exposed when erosive wind 

and water remove upper layers of soil. These eroded 

portions create rock outcrops or "break" areas with gravel 

and rock on the surface. Ina few areas, erosion has been so 

great that barren siltstone surfaces are exposed. Windswept siltstone barrens and ravines have minimal soil 

development but support interesting plant communities. 

Sandy soils occur along stream terraces and on leeward 

sides of some hills. 

Over time, the erosive forces of wind and water have 

influenced the soils on the undulating hills of the prairie. 

Mobile soil particles, such as silt and clay, have eroded 

from higher topographic positions and have been deposited in lower areas. Therefore, swale areas often have finer 

textured soils than ridgetops. This difference in soil texture is sometimes reflected by a greater abundance of 

buffalo grass in swales. Some drainages, playas, and 

riparian areas have an accumulation of salts on or near the 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 3 
surface. Alkaline-tolerant plant species that occur in these lands. Currently, most biologists refer to the vegetation of 

areasinclude Ambrosia tomentosa (perennialbursage), Che- the Pawnee National Grassland as shortgrass steppe. Lonopodium glaucum (oakleaf goosefoot), Distichilis spicata cal residents refer to this same shortgrass steppe region as 

(saltgrass), Rayjacksonin annua (annual goldenweed), the plains, the shortgrass prairie, the prairie, or "The 

Sporobolus airoides (alkali sacaton), and Suaeda calceoliformis Pawnee." 

(broom seepweed). Maps and detailed descriptions of the 

soil series types that occur in this study area can be found 

in Crabb (1981). Surrounding Vegetation 

Vegetation 

The vegetation in northeastern Colorado is classified 

by The Nature Conservancy (1997) as the Central Shortgrass Prairie Ecoregion. This ecoregion is the southern 

portion of the Great Plains-Palouse Dry Steppe Province 

of Bailey (1995). The term shortgrass steppe is perhaps the 

most appropriate word for the Pawnee National Grassland. The argument for this is that "steppe" (Russian for 

"step") has long been used as the name for similar grassland areas in Asia. For this reason Walter (1973) suggested 

that this name also be used for grasslands in the western 

hemisphere. 

The shortgrass steppe or shortgrass prairie has traditionally been separated from other grasslands in the Great 

Plains area on the basis of the relative height of the 

dominant grasses. The most arid grassland is the blue 

grama/buffalo grass dominated shortgrass steppe. The 

midgrass and tallgrass prairies have more rainfall and 

progressively taller dominant grass species. There are 

areas of blue grama in both midgrass and tallgrass prairies, usually at more exposed locations. Weaver, a wellknown ecologist, once considered the shortgrass prairie as 

nothing but an overgrazed midgrass or tallgrass prairie. 

This view is no longer held by ecologists. Besides the low 

rainfall and dominance of short grasses, one of the better 

means to distinguish between the shortgrass and the 

midgrass or tallgrass prairies is that in the shortgrass 

steppe region all of the available soil moisture is transpired before the end of the growing season (Brown, 

undated). In general, less than 50 percent of the ground in 

shortgrass steppe is covered by vegetation. 

Early settlers of the Great Plains had little problem 

recognizing the low rainfall amounts in the shortgrass 

steppe. Compared to tallgrass and midgrass prairies, much 

less of the shortgrass steppe was plowed and converted to 

agricultural land. Nonetheless, an estimated 60 percent of 

the high plains grassland in Weld County had been plowed 

by 1930 (Rhoads and Rhoads, undated), which contributed to the Dust Bowl. The presence of unplowed areas 

and the desire to reduce wind erosion after the Dust Bowl 

led to the protection of shortgrass prairies in eastern 

Colorado as the Pawnee and Comanche National GrassThe floristic survey area is surrounded by different 

types of vegetation. Toward the north there is a decrease 

in temperature and an increase in annual precipitation 

amounts. These changes result in a decrease in the abundance of Bouteloua gracilis (blue grama), a warm-season 

species, and an increase in the,abundance of cool-season 

species. Cool-season plant species that are more common 

in southeastern Wyoming include Astragalus drummondii 

(Drummond's milk-vetch), Koeleria macrantha (junegrass), 

Pascopyron smithii (western wheat grass), and Sfipa comata 

(needle and thread). Southeastern Wyoming also has more 

sandy soil and, therefore, larger areas of Calamovilfa 

longifolia (prairie sandreed). 

West of the study area is a transitional area or ecotone 

between the shortgrass steppe and the Rocky Mountains. 

Plant species present along perennial streams toward the 

west include Gentianella amarella (little gentian), Hippuris 

vulgaris (mare's tail), and Stackys palustris (hedge-nettle). 

The absence of these species from the survey area is an 

indication of few riparian areas. Along Lone Tree Creek 

(toward the west) and Cottonwood Creek (toward the 

north) is Gaura neomexicana ssp. coloradensis (Colorado 

butterfly plant), a rare plant species that has not been 

located in the survey area. Plant species that are more 

common toward the foothills than in the survey area 

include Astragalus tridactylicus (three-leaved mild-vetch), 

Helianthus purnilus (foothill's sunflower), Lupinus argenteus 

(silvery lupine), Oxytropis multiceps (dwarf loco), and 

Townsendia kookeri (Easter daisy). 

South of the survey area is a mosaic of agricultural land, 

sandhills, and shortgrass steppe vegetation. From northeastern to southeastern Colorado the general appearance 

of the shortgrass steppe is similar, but there are changes in 

the presence, frequency, and abundance of plant species. 

Astragalus rnollissimus (woolly locoweed) and Solanum 

rostratum (buffalo bur) become more abundant toward the 

south. Northern species that are infrequent or absent 

toward the south include Astragalus sericoleucus (silky 

orophaca), Musineon divaricatum (leafy wild parsley), and 

Scutellaria brittonii (Britton's skullcap). Common plant 

species toward the south that are absent in the survey area 

include Artemisia bigelovii (Bigelow's sagebrush), 

Glandularia bipinnatifida (Dakota vervain), Leuceleneericoides 

(white aster), Hilaria jamesii (galleta grass),Pectis angustifolia 

(narrowleaf pectis), and Proboscidea louisianica (devil's 

claw). 

4 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
Compared to the survey area, southeastern Colorado 

has more endemic plant species. Among these are Ambrosia linearis (Plains ragweed), Frasera coloradensis (Colorado 

green gentian), Oenotlzera harringtonii (Arkansas valley 

evening primrose), and Oonoysis foliosa var. monocephala 

(rayless goldenweed). Besides these four Colorado 

endemics, other southeastern plant species that are associated with specific soils types include Frankenia jamesii 

(alkali heath bush), Stipa neonzexicana (New Mexican 

needle-and-thread), several Penstemon species, and several Eriogonum species. The presence of more endemic 

plant species in southeastern Colorado is related to factors 

such as a greater variety of edaphic conditions, warmer 

weather, and a closer proximity to plant species from 

more southern floristic provinces (Clark 1996). 

Shortgrass steppe vegetation continues toward the east 

of the study area as far as western Kansas. As rainfall 

increases toward the east there is no marked boundary 

between shortgrass and mixed-grass prairies. Instead, 

there is a gradual transition to mixed-grass prairie in 

central Kansas and then to tall-grass prairie in eastern 

Kansas. An indication of greater rainfall toward the east is 

an increase in the number of cultivated fields and a shift 

from dryland wheat to corn fields. 

Also toward the south and east are large, sometimes 

extensive areas of sandy soils. These sandhills are included in the Central Shortgrass Ecoregion but do not 

have shortgrass steppe species as dominants. Instead, 

Artemisia filifolia (sand sage) and Calarnovilfa longifolia (prairie sandreed) are often abundant. Other species that occur 

in sandy sods toward the east, but not in the survey area, 

are Amaranthus arenicola (sandhills pigweed), Cyperus 

schweinitzii (sand sedge), Dalea villosa (silky prairie clover), Eriogonum annuurn (annual buckwheat), Euploca 

convolvulacea (sand heliotrope), Ipomopsis longiflora (gilia), 

Muhlenbergia pungens (sand muhly), Palafoxia sphacelata 

(palafoxia), Polanisia jamesii (cristatella), Redfieldia flexuosa 

(blowout grass), and Triplasis purpurea (sandgrass). Pens temon haydenii (blowout penstemon) isa rare endemicin the 

sandhills of Nebraska that is not known to occur in Colorado. 

Habitats Within the Survey Area 

For this report each shortgrass steppe plant species was 

assigned to one of six habitats (table 1). This approach to 

habitat designation allows plant species distributions to 

determine the number of habitats that are present. For 

example, since certain plant species occur only along 

roadsides and in disturbed areas, it was necessary to 

designate roadside and disturbed sites as a habitat type. In 

like fashion, some plant species occur only on siltstone 

barrens or on exposed rocky shale or gravel breaks. Therefore, exposed barrens and breaks were also designated as 

a habitat type. A plant species was assigned to a particular 

habitat whenever it consistently occurred at a particular 

location or edaphic condition. Some plant species, such as 

Bouteloua gracilis (blue grama), occur in several habitats. 

For species that routinely occur in multiple habitats, the 

location where it was most abundant (field observations) 

was selected as the "primary" habitat. In the case of blue 

grama this was the open steppe. 

Table 1. A comparison of the number of plant species in six primary habitats and three duration categories for 406 native and 115 

exotic plant species. 

Open Sandy Breaks1 Cliffs1 Roadsides1 

stewe soils barrens ravines Riparian disturbed soils Total (%I 

Native 

annuals 22 12 0 4 23 

biennials 5 1 1 4 10 

perennials 80 19 28 50 112 

subtotal 107 32 29 58 145 

Exotic 

annuals 0 2 0 0 26 

biennials 0 0 0 0 5 

perennials 0 0 0 0 20 

subtotal 0 2 0 0 51 

Total 107 34 29 58 196 97 521 

(percentages) 21 % 6% 6% 11% 38% 18% 100% 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 5 
Open steppe 

The most common habitat on the Pawnee National 

Grassland and in this survey area is open steppe. This 

habitat of flat plains and undulating hills covers more 

than 80 percent of the study area. The dominant species 

are Bouteloua gracilis (blue grama) and, to a lesser extent, 

Buchloe dactyloides (buffalo grass). Other characteristic 

plant species of open steppe habitat are Aristida purpurea 

(threeawn), Artemisiafrigida (fringed sage), Ch ysothamnus 

nauseosus var. nauseosus (rabbitbrush), Gutierrezia sarothrae 

(snakeweed), Muhlenbergia torreyi (ring muhly), Opuntia 

polyacantha (prickly pear cactus), Pascopyron smithii (western wheatgrass), Psoralidium tenuiflorum (scurf pea), and 

Sphaeralcea coccinea (scarlet globemallow). 

Sandy soils 

Throughout the floristic survey area are small and 

scattered patches of sandy soil. These frequently occur 

along dry creek beds, in stream terraces, and near some 

hilltops. As discussed above, there are large areas of sandy 

soil with additional plant species characteristic of sandy 

soil toward the east and south of the floristic survey area 

(Yuma and southern Weld Counties). Within the survey 

area only about 5 percent of the area has sandy soil. 

Characteristic sandy soil shrubs are Artemisiafilifolia (sand 

sage) and Yucca glauca (small soapweed). Plant species 

within the survey area that often occur on sandy soil 

include Artemisia campestris (western sagewort), 

Corispermum hyssopifolium (hopleaf tickseed), Cycloloma 

afriplicifolium (tumble ringweed), Evolvulus nutallianus 

(Nuttall's evolvulus), and Psoralidium lanceolatum (lemon 

scurf pea). The infrequent Chenopodium cycloides (sandhills 

goosefoot) is known from Weld county but has not been 

discovered in the survey area. 

Breaks and barrens 

Plants in this habitat have no cliff or ravine walls to 

shade them from the sun and seldom occur in other 

habitats. Important characteristics of this habitat are minimal soil development and a substrate that is either barren 

siltstone or with abundant rock or gravel. Common plant 

species on exposed siltstone barrens near the Chalk Bluffs 

are Eriogonum brevicaule (shortstem eriogonum) and the 

infrequent Shinnersoseris rostra ta (shinnersoseris). Frequent 

in the vicinity of the Pawnee Buttes are Cryptantha cana 

(cryptantha), Eriogonum pauciflorum (fewflower buckwheat), Leptodactylon caespitosum (clump slenderlobe), and 

Hedysarum boreale (sweet broom). On the barrens in both 

areas are Arenaria hookeri (tufted sandwort), Astragalus 

sericoleucus (silky orophaca), Ipomopsis spicata (spike gilia), 

Comandra umbellata (bastard toadflax),Astragalus spatulatus 

(draba milkvetch), and Phlox hoodii (Hood's phlox). 

The tufted sandwort occurs on both gravel and siltstone barrens, but only on some barrens does it develop a 

unique mound shape (figure 2). This shape makes it easy 

to recognize and one of the most conspicuous plants in the 

region. The spreading perennial mat that this plant produces protects the siltstone beneath it from erosion. Meanwhile, the wind and water slowly erode the siltstone 

around this mat. Over time (the age of these plants could 

be hundreds of years), the margins of this mat droop down 

to occupy space where soil was, while the center of the 

Figure 2: A flowering Arenaria 

hookeri (tufted sandwofl) on a 

siltstone barren of the Pawnee 

National Grassland. 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
plant remains in the same place. The result is a domeshaped, often symmetrical mat that can be over 20 cm tall. 

Barren and break plant species at or near the southern 

edge of geographical ranges include Astragalus gilviflorus 

(plains orophaca), Lesquerella alpina (bladderpod), 

Leptodactylon caespitosum (clump slenderlobe), Lomatium 

nuttallii (Nuttall's lomatium), Machaeranthera grindelioides 

(ragless goldenweed), Parthenium alpinum (Wyoming feverfew), and Stenotus armeroides (goldenweed). 

Cliffs and ravines 

Many native plants, mainly woody species, occur in the 

shade of cliffs or ravines. Ravines are most common in the 

north and northeastern portions of the survey area. This 

includes Dave's Draw, major creek drainages, Indian 

Caves, and the vicinity of the Pawnee Buttes. The partial 

shade afforded to plants in this habitat and their deep 

roots apparently facilitate their survival. Plant species 

that occur in these areas include Juniperus scopulorum 

(Rocky Mountain juniper), Prunus virginiana (chokecherry), 

frequent riparian species are Agalinis tenuifolia (gerardia), 

two species of Sisyrinchium (blue-eyed grass), 

Schoenoplectus saximontanus (bulrush), and Triglochin maritima (arrowgrass). An isolated population of Erigeron 

lonchophyllus (fleabane daisy)occurs along a tributary of 

Little Crow Creek, but this fleabane daisy is more common at higher elevations. 

Common native plant genera in riparian areas are 

Aster, Bidens, Carex, Eleocharis, Equisetum, Juncus, Lycopus, 

Polygonum, Rumex, Schoenoplectus, Trifolium, and Veronica. 

The familiar Populus deltoides (cottonwood tree) and Salix 

exigua (sandbar willow) are locally common along many 

creeks. Several exotic Tamarix ramosissima (salt cedar) 

saplings were seen at one location along Little Owl Creek 

in 1994, but have not yet been relocated. Common riparian 

exotics include the abundant Cirsium arvense (Canada 

thistle), an occasional Elaeagnus angustifolius (Russian 01- 

ive), Iva xanthifolia (marsh elder), Poa pratensis (Kentucky 

blue grass), Polypogon monspeliensis (rabbitfoot grass), and 

the omnipresent Taraxicum officinale (dandelion). 

and two species of Ribes (gooseberry). Under shaded Roadsides and ledges in the Indian Caves area areMaianthemum stellatum 

(spikenard), Parietaria pensylvanica (pelitory), Urtica dioica Areas covered by roads, disturbed areas, pens, and 

(nettles), and two species of fern. buildings cover less than 5 percent of the study area. The 

crowned county roads allow water to accumulate in side 

Riparian ditches. This increase in water allows some native and 

The creeks in the study area with the most water were 

recognized long ago by early settlers. These settlers often 

built earthen dams across creeks or near springs to capture 

water for livestock. In most cases, the only time there is 

enough water to accumulate behind small dams or in 

playas is after meltdown of a snowpack or a large rainfall 

event. The exceptions are a few creeks and underground 

springs that usually have at least some water, even in dry 

years. The riparian areas with the most perennial water 

are Coal Creek, Willow Creek, South Pawnee Creek, Little 

Crow Creek and its tributaries, Two Mile Creek and Lone 

Tree Creek. Lone Tree Creek is the only one of these creeks 

that does not occur on the Pawnee National Grassland. 

Two Mile Creek is one of the creeks that has been least 

modified by dams. Other creeks in the survey area that 

occasionally have ponds with aquatic or riparian vegetation are Geary Creek, Owl Creek, Little Owl Creek, Wild 

Horse Creek, Howard Creek, Eastman Creek, and 

Robinson Creek. 

Greater water availability has provided a habitat for 

many native and exotic plant species. Among the obligate 

aquatic plant species are Heteranthera limosa (mud plantain), Marsilea vestita (clover fern), the infrequent 

Potamogeton diversifolium (waterthread pondweed), 

Potamogeton foliosus (leafy pondweed), and Ranunculus 

aquatilis (white water crowfoot). Two infrequent riparian 

herbs that must be rooted in mud are Elatine triandra 

(waterwort) and Limosella aquatica (mudwort). Other inmany exotic plant species to become established along 

roadsides. Among the native plant species that occur 

along roadsides are immigrant species from higher rainfall areas. Roadside corridor arrivals from the east include 

Cichorium intybus (chicory),Mirabilis nyctaginea (wild fouro'clock), Panicum virgatum (witchgrass), Physalis virginiana 

(ground cherry), and Vicia americana (American vetch). 

Other arrivals from the north or west are Stipa robusta 

(sleepy grass) and a few Artemisia cana (silver sage) shrubs 

near Highway 85 north of Nunn. Two widespread native 

but ruderal plant species that occur along roadsides are 

Asclepias speciosa (milkweed) and Helianthus annuus (common sunflower). Picradeniopsis oppositifolia (bahia) and 

Ambrosia tomentosa (perennial bursage) are examples of 

native steppe species that can occur in large patches along 

roadsides. 

Native plants are present, but the most abundant roadside plant species are introduced species. Common among 

these are Bromus tectorum (brome grass), Conyza canadensis 

(horseweed), several Descurainia (tansy mustard) taxa, 

Kochia scoparia (alkaliweed), Melilotus officinalis (yellow 

sweet clover), Salsola tragus (tumbleweed), Salvia reflexa 

(lanceleaf sage or chia), Sisymbrium altissimum (tumble 

mustard), Tragopogon dubius (goat's beard), and Tribulus 

terrestris (tackbur). Two roadside exotics with bright yellow flowers that are increasing in abundance in the survey 

area are Linaria dalmatica (dalmatian toadflax) and 

Verbesinia encelioides (cowpen daisy). 

USDA Forest Sewice Gen. Tech. Rep. RMRS-GTR-17.1998 7 
or exotic plant taxa. The duration categories for the 406 

Nomenclature 

There are several field guides and floras available from 

which to select the most appropriate scientific name for plant 

species that occur in northeastern Colorado. These include 

Dorn (1992), Great Plains Flora Association (1986), and Weber and Wittmann (1992 and 1996). In addition, a PLANTS 

(Plant List of Accepted Nomenclature, Taxonomy, and 

Symbols) database is maintained by the US. Department 

of Agriculture's Natural Resources Conservation Service 

(1995). PLANTS is continually updated and is available 

online at http://trident.itc.nrcs.usda. gov/plants/. The 

first three volumes of Flora of North America North ofMexico 

(1993-1997) have also been published. 

For each plant species in the survey area, a widely 

accepted scientific name was placed first on the checklist. 

Scientific names in the available volumes of Flora of North 

America North of Mexico (mainly ferns and Ranunculaceae) 

and in Rollins (1993) were used. For other plant species, I 

compared the scientific names that are used by the Rocky 

Mountain Herbarium (University of Wyoming, Laramie, 

WY), R. L. McGregor Herbarium (University of Kansas, 

Lawrence, KS), University of Colorado Herbarium (Boulder, CO), and the PLANTS database. If all sources agreed, 

I placed this scientific name first on the checklist. When 

differences in plant nomenclature occurred, I also searched 

Dorn (1992), Hickman (1993), Hitchcock (1950), Great 

Plains Flora Association (1986), Weber and Whittman 

(1992), and Welsh et al. (1993). A widely accepted scientific name was selected and placed first. Common synonyms and proposed scientific names for taxa were listed 

in brackets after this name. 

For each plant species on this checklist, a representative 

plant collection was examined and designated a voucher 

specimen. After each scientific name are also the names of 

plant collectors, collection numbers of representative collections, and the herbarium acronyms that indicate the 

herbarium where a collection is archived. Plant specimens 

that occur near but not in the survey area (Larimer, Logan, 

or Weld counties) were included on the checklist in parentheses. The name Weld in parentheses indicates a voucher 

specimen from this county but outside the survey area. A 

few specimens that other botanists or I have seen but not 

yet collected are listed as reported. 

Distribution 

- 

native plant taxa were 74 percent perennials, 20 percent 

annuals, and 6 percent biennials. The duration categories 

for the 114 exotic plant taxa were 28 percent perennials, 60 

percent annuals and 12 percent biennials. For both native 

and exotic plants, the biennial category included plant 

species that sometimes also occur as annuals or perennials. 

The distribution of native and exotic plant taxa among 

six habitat categories indicates that 36 percent of native 

and 44 percent of exotic plant taxa occur primarily in 

riparian habitats (table 1). This is a large proportion since 

riparian areas comprise less than 10 percent of the survey 

area. In contrast, only 26 percent of the native plant taxa 

occur primarily in the open steppe, a habitat that occupies 

more than 80 percent of the survey area. Approximately 

53 percent of the exotic plant species occur primarily in 

disturbed soils along roadsides. 

The distribution of native and exotic plant taxa among 

eight life form categories indicated that 17 percent of the 

native and 18 percent of the exotic taxa are graminoids 

(table 2). More than 70 percent of both native and exotic 

plants were forbs. Details on the number and distribution 

of native and exotic plant species among life forms and 

habitat categories are on tables 1 and 2. 

Comparisons of Distributions 

The four glacial periods that affected the Great Plains 

area are named for the states where their southernmost 

extention occurred. The Nebraska glacial peroid began 

about one million years ago and was followed by the 

Kansan, Illinoian, and the Wisconsin. The retreat of the 

Wisconsin glacier began approximately 12,000 years ago 

(Dort and Jones 1970). The prairie of eastern Colorado has 

been present at least this long, although initially it probably had different dominants. 

The relatively short amount of time since much colder 

climatic conditions persited has not allowed for extensive 

speciation of plant species. The Great Plains area has 

relatively low rates of plant endemism. Risser (1988) 

reported that less than 15 Great Plains plant species are 

listed or proposed to be listed as federally threatened or 

endangered taxa. There are only about 50 endemic plant 

species in the entire region. Currently, the only Pawnee 

National Grassland plant species that is infrequent enough 

to be listed by federal agencies is Parthenium alpinum 

(Wyoming feverfew). This taxon is considered a sensitive 

species by the USDA Forest Service and has a federal 

status of C3. A C3 status is a plant that has been determined to be more abundant than previously thought and 

A total of 521 plant taxa were reported from the floristic is not subject to any immediate threat. Wyoming feverfew 

survey area. Of this total, 115 (22 percent) were introduced is very abundant on limestone hills in Platte County, 

8 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
Table 2. A comparison of the number of plant species in eight life form and three duration categories for 406 native and 115 exotic 

plant species. 

Aquatics1 Vines1 

Graminoids Herbs Trees Shrubs succulents parasites Total (%) 

Native 

annuals 6 70 114 0 81 

biennialsa 0 23 23 

perennials 65 190 6 2 1 616 414 299 

subtotal 71 283 6 21 711 0 414 406 (78%) 

Exotic 

annuals 13 53 012 

biennialsa 0 14 

perennials 9 18 3 1 0 

subtotal 22 85 3 1 012 

Total 93 368 9 22 711 2 614 521 

(percentages) 18% 71 % 2% 4% 3% 2% 100% 

"The biennial life form includes biennial plants that can also occur as annuals and/or perennials. 

Wyoming, but only a few plants in this species have been 

found in northeastern Colorado. This plant is currently 

known from only one location on the Pawnee National 

Grassland. 

With few endemic plant species, it is not surprising that 

most plant species in the Great Plains have geographic 

ranges that extend beyond the Great Plains region (Great 

Plains Flora Association 1986). To better quantify the size 

of geographic ranges for plant species that occur in this 

study area, a record was made of the number of states 

where each plant species is known to occur. The total 

number of states where each plant species occurred was 

determined for all native and exotic plant species (figure 

3). The data on presence or absence in each state were 

obtained from the PLANTS database. Supplemental range 

distribution information was obtained from Hitchcock 

(1950), Flora of North America North of Mexico (1997), and 

Welsh et al. (1993). 

One limitation to the comparison of geographic distributions based on the number of states is that states are of 

different sizes. In addition, when the range of a plant 

species barely enters a state, this state is tallied as a 

location for that species. Because of these constraints, no 

differences in geographic ranges could be presumed for 

plant species that differed in occurrence by only a few 

states. 

Despite these constraints, the number of states where 

each plant species occur allows for interesting comparisons. For example, the Great Plains area covers 12 states. 

A tally of survey species that occur in 1-12 states indicates 

the number of species with ranges that are approximately 

the same size or smaller than the Great Plains area. This 

tally indicated that 126, or 31 percent, of 406 native species 

occur in 1-12 states. The complementary statistic is that 

280 (about two-thirds) of the native plant species in the 

survey area have a geographical range larger than the 

Great Plains region. 

Native plant species that occur in the 1-12 states are: 16 

species in 1-5 states, 72 species in 6-10 states, and 38 

species in 11-12 states. There were no Colorado endemic 

plant species in the survey area. Native plant species that 

occur in only two states are Astragalus tridactylicaus (threeleafed milk-vetch) and Parthenium alpinum (Wyoming 

feverfew); species that occur in three states are Helianthus 

pumilis (foothill's sunflower) and Delphinium geyeri (Geyer's 

larkspur); species that occur in four states are Eriogonum 

pauciflorurn (few-flowered buckwheat), Musineon 

tenuifolium (Nuttall's biscuitroot) and Oxytropis multiceps 

(dwarf locoweed); and species that occur in five states are 

Scutellaria brittonii (Britton's skullcap), Cryytantha cana 

(mountain cat's-eye), Afriplex gardneri var. utahensis 

(moundscale), Paronychia depressa (nailwort), Townsendia 

grandiflora (Easter daisy), and Chenopidium cycloides (sandhill goosefoot). 

The geographic distribution of exotic plant species was 

much greater than that of native plant species (figure 3). 

The median number of states where native plant species 

occur is 16, while the median number of states where 

exotic plant species occur is 43. Over half of the exotic 

plant species in this study area occurred in 40 or more 

states. Many of these exotic plants are widespread annuals of Eurasian origin. On the other hand, several exotic 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
Figure 3. The number of states where 

native and exotic plant species from the 

survey area are known to occur. Percentages are based on 406 native and 

115 exotic plant species. Over half of all 

native plant species occur in less than 20 

states, while more than half of all exotic 

species occur in more than 40 states. 

- 

Native Plants Exotic Plants 

0 *~i---F 

plant species have small geographic ranges. The exotic 

plant species with the smallest geographic ranges were 

Thinopyrum yonticurn (tall wheatgrass) in six states and 

Scorzonera laciniata (cut-leaf salsifly) in five states. The 

range of these and of other exotic plant species will probably continue to expand. Tall wheatgrass may already be 

seeded into pastures of additional states and has simply 

not yet been reported. 

A comparison of the names on this checklist with 

species that are known to occur in Wyoming indicated 

that nine plant species in the survey area have not yet been 

reported from Wyoming. Two of these are the weedy 

Hibiscus frionum (flower-of-an-hour) and Dafura stramonium (jimson weed). Seven native plants not yet known 

from Wyoming are Astragalus plaffensis (Platte milk-vetch), 

Celfis reticdata (netleaf hackberry), Chenopodium incanum 

(goosefoot), Heteranfhera lirnosa (mud plantain), Ipomopsis 

laxiflora (gilia), Orobanche mulfiflora (broomrape), and 

Quincula lobafa (purple ground cherry). Each of these 

plant species is at the northern or eastern portion of its 

geographic range. 

Exotic Plant Species 

Sims (1988) suggested that the shortgrass steppe region 

is less invaded by exotic plant species than other North 

American grasslands. This study identified more that 22 

percent of the species in the flora as exotics. Most of these 

occur near cultivated land, along roadsides or in riparian 

areas. I agree with Sims in that none of the shortgrass steppe 

exotics identified cover extensive areas of the open steppe 

habitat. However, a few exotics are locally common in 

disturbed soils of the open steppe, including around fence 

Number of States 

posts. These species include Bromus fecforum (brome grass), 

Kochia scoparia (kochia), Salsola fragus (tumbleweed), and 

Sisymbrium alfissimum (tumble mustard). Each of these 

four species, especially brome grass, is more common on 

the open steppe during a wet spring and may persist in the 

soil seed bank during dry years. Therefore, these exotics 

may be able to hold on to steppe areas they gain during 

wet years as seeds in the soil and continue to advance 

across the open steppe during each subsequent wet year. 

Common exotics in riparian areas are Cirsium arvense 

(Canadian thistle), Conyza canadensis (horseweed), and 

several species of Polygonum (smartweed). As of 1998, the 

Canadian thistle is the most aggressive perennial exotic 

on the Pawnee National Grassland. 

The cropland and roadside exotics can be separated 

into at least three groups of species. The first group includes species that occur along roadsides and in disturbed 

sites throughout the survey area. A second group includes 

species that are confined mainly to cropland, especially to 

areas with irrigated crops. These include Abutilon 

fheophrasti (velvet leaf), Aegilops cylindrica (jointed 

goatgrass), Datura stramonium (jimson weed), Hibiscus 

frionum (flower-of-an-hour), Panicum millaceum (proso 

millet), and Secale cereale (wild rye). These species often 

occur in sugar beet, wheat, bean, gardens, corn and wheat 

fields, respectively. Other plant species that occur primarily in or near irrigation ditches and gardens are Anemone 

canadensis (meadow anemone), Malva parviflora (smallfruited mallow), Setaria glauca (yellow foxtail), and Sefaria 

viridis (green foxtail). 

A third group includes species with moisture requirements that are intermediate to the wet conditions of irrigated cropland and the more xeric conditions of prairie 

roadsides. These exotics occur along ditches near irri10 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
gated crops, along urban roadsides, and in vacant town 

lots. During wet years these species can spread into more 

xeric roadside areas and into riparian areas. These more 

mesic exotics include Bromus inermis (smooth brome), 

Chorispora tenella (blue mustard), Convolvulusarvensis (field 

bindweed), Lactuca serriola (prickly lettuce), Polygonum 

nviculare (knotweed), Scorzonera lacininfa (false salsify), 

and Solanum triflorum (cut-leaved nightshade). Chloris 

virgata (feather fingergrass) is a weedy grass that occurs in 

southern Weld county but has not yet invaded the survey 

area. This Chloris species thrives during hot, wet summers and may eventually expand along roadsides as far 

north as Wyoming. An annual grass that occurs occasionally in disturbed urban sites is Bouteloua simplex (sixweeks grama). 

Homestead and Planted Species 

There are several plant species that were planted long 

ago that still persist around old homesteads or buildings. 

A commonly planted tree that persists in many areas is 

Ulmus pumila (Siberian elm). There are also a few planted 

Acer negundo (boxelder maple) trees. The Siberian elm is 

on the checklist but the boxelder maple tree is not because 

the boxelder maple trees do not appear to be able to reestablish from seed. Other species that were planted, but 

that do not appear to reestablish from seed, are Prunus 

americana (American plum), Parthenocissus sp. (Virginia 

creeper), and Syringa vtdgaris (common lilac). Exotic plant 

species that have been able to survive and to re-establish 

themselves without human help in the survey area are 

Artemisia absinthium (large absinthe or common wormwood), Mavrubium vulgare (horehound mint), Lycium 

barbnrum (matrimony vine), and Saponaria officinalis (bouncing bet). 

Since the early 1800s, Arfemisia absinthium has become 

naturalized throughout the Great Plains region, often 

along roadsides and riparian areas, and is now present in 

at least 31 states. It was once used as a vermifuge for 

livestock and perhaps also for people. Field observations 

from 1992-1997 suggest that the area covered by large 

absinthe along Willow Creek in the Pawnee National 

Grassland is increasing. 

Literature Cited 

Bailey, R.G. 1995. Descriptions of the ecoregions of the United States. 

USDA Forest Service, Miscellaneous Publication 1391. 

Brown, L. undated. Grasslands. The Audubon Society Nature Guides. 

Alfred A. Knopf, Inc. New York, NY. 

Clark, D.A. A floristic survey of the Mesa de Maya region. Natural 

History Inventory of Colorado, Boulder. No. 17:l-44. 

Crabb, J.A. 1981. Soil survey of Weld County, Colorado northern part. 

USDA Soil Conservation Service and Forest Service in cooperation 

with Colorado Agricultural Experiment Station. 

Dorn, R.D. 1992. Vascular plants of Wyoming (second edition). Mountain West Publishing, Cheyenne, Wyoming. 340 pp. 

Dort, S.W. Jr. and J.K. Jones Jr. eds. 1970. Pleistocene and recent environments of the central Great Plains. University Press of Kansas, 

Lawrence. 433 pp. 

Flora of North America North of Mexico 1993-1997. Flora of North 

America Editorialcommittee, Volumes 1-3, Oxford University Press, 

New York, NY. 

Great Plains Flora Association. 1986. Flora of the Great Plains. University of Kansas Press, Lawrence, KS. 

Hickman, J.C., editor. 1993. The Jepson manual: Higher plants of California. University of California Press, Berkeley, CA. 

Hitchcock, A.A. 1950. Manual of the grasses of the United States. Second 

Edition, revised by A. Chase. Dover Publication, Inc. 

Lugn A.L. and Luhn, Richard V. 1956. The general tertiary geomorphology in Nebraska and the northern Great Plains. The Compass. Vol33 

(2):99-114. 

Rhoads, D. and L. Rhoads (undated). Introduction to the Pawnee National Grassland history. Report to USFS/PNG Office, Greeley, CO, 

5 PP. 

Risser, P.G. 1988. Diversity in and among grasslands. In: Biodiversity, 

E.O. Wilson Editor. National Academy Press, Washington D.C. 

Rollins,R.C. 1993.Thecruciferaeof continentalNorth America. Stanford 

University Press, Stanford, CA. 

Sims, P.L. 1988. Grasslands. Pp. 256-286. In: Barbour M.G. Billings Eds. 

North American terrestrial vegetation. Cambridge University Press, 

Cambridge, MA. 

Swahn, J.O. 1991. The lore of spices: Their history, nature and uses 

around the world. Barnes & Noble Books, New York, NY. 

Scott, G.R. 1978. Map showing geology, structure, and oil and gas fields 

in the Sterling lo x 2" quadrangle, Colorado, Nebraska, and Kansas. 

Department of the Interior, United States Geological Survey, Miscellaneous Investigations Series: Map 1-1092. 

The Nature Conservancy. 1997. Archipelagos of hope: Guidelines for 

ecoregion-based conservation, ~rlin~ton, VA. 84 pp. 

Thornbury, W.D. 1969. Principles of geomorphology. John Wiley & 

Sons, Inc. New York, NY. 

Trimble, D.E. 1993. The geologic history of theGreat Plains. Reprint with 

minor revisions of Geological Survey Bulletin 1493. Theodore 

Roosevelt Nature and History Association, Medora, ND. 54 pp. 

United States Department of Agriculture, Soil Conservation Service. 

1995. PLANTS (Plant List of Accepted Nomenclature, Taxonomy, 

and Symbols). National Plant Data Center, Baton Rouge, LA. 

Walter, H. 1973. Vegetationof theearth inrelation to climate and the ecophysiological conditions. The English University Press Ltd., London; Springer-Verlag, New York-Heidelberg-Berlin. 

Weber, W.A., and R.C. Wittmann. 1992. Catalog of thecolorado flora: A 

biodiversity baseline. University Press of Colorado, Niwot, CO. 

215 pp. 

Weber, W.A., and 1i.C. Wittmann. 1996. Colorado flora: Eastern slope 

(revised edition), University of Colorado Press, Niwot, CO. 

Welsh, S.L., N.D. Atwood, S. Goodrich, and L. Higgins. 1993. A Utah 

flora. Print Services, Brigham Young University, Provo, Utah. 

Wilken, G.C. 1987. Climate and weather of the Great Plains. Pp 18-20. In: 

John E. Mitchell, Ed. Impacts of the Conservation Reserve Program 

in the Great Plains. Gen. Tech. Rep. RM-158. Fort Collins, CO: US. 

Department of Agriculture, Rocky MountainResearchStation: 18-20. 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
CHECKLIST OF VASCULAR PLANT SPECIES 

The first listed name is a widely accepted scientific name for this taxon (see Nomenclature section on page 8). An asterisk (*) 

indicates an exotic taxon. Names in square brackets are synonyms or proposed names. If only a genus name is in a bracket, the 

specific epithet of this genus is the same as the first listed name. The names of plant collectors, collection numbers, and acronyms 

of herbaria where a voucher is deposited are included: CU=University of Colorado Herbarium at Boulder; CS=Colorado State 

University herbarium at Fort Collins; RM=Rocky Mountain Herbarium at the University of Wyoming; and KHD=Kalmbach 

Herbarium Denver at the Denver Botanic Gardens. A county name in parentheses indicates a collection from this county or in 

Weld County, but outside the study area. A reported taxon is one that has been seen but not collected. 

FERNS AND FERN ALLIES COMMON NAME 

Dryopteridaceae 

Woodsia oregana D.C. Eaton ssp. cathcartiana (B. L. Robinson) Windham Oregon cliff fern 

Hazlett 771 4/CS 

Equisetaceae 

Equisetum hyemale L. ssp. affine (Engelmann) Calder & Roy L. Taylor common scouring rush 

[Hippochaete] Lederer 97-252 (Logan) 

Equisetum laevigatum A. Braum [Hippochaete] Klein 3280lCS smooth scouring rush 

Marsileaceae 

Marsilea vestita Hooker & Greville [M. mucronata] Hazlett 1001 8/CU 

Pteridaceae 

Cheilanthes fee; T. Moore [Sinopteridaceae] Lederer 451 0/CU 

western water-clover 

slender lip fern 

GYMNOSPERMS 

Cupressaceae 

Juniperus scopulorum Sargent [Sabina] Hazlett 7796lCS (at CPER) 

Pinaceae 

Pinus flexilis E. James Hazlett 7533/CS (at CPER) 

Pinus ponderosa Douglas ex Lawson & C. Lawson ssp. scopulorum 

Engelman in S. Watson (reported) 

Rocky Mountain juniper 

limber pine 

mountain ponderosa pine 

ANGIOSPERMS: MONOCOTS 

Agavaceae 

Yucca glauca Nuttall var. glauca Sawyer 1 08/CS 

Alismataceae 

Sagittaria cuneata Sheldon Neese & Andrews l6OO5/CS 

Sagittaria latifolia Willdenow var. latifolia Hazlett 10027/CS 

Commeliniaceae 

Tradescantia occidentalis (Britton) Smyth var. occidentalis 

Walter 171 6/CS 

Cyperaceae 

Bolboschoenus maritumus (L.) Palla ssp. paludosus (Nelson) T. Koyama 

[Scirpus maritimus var. paludosus] Hazlett 9893lCS 

Carex aquatilis Wahlenberg ssp. aquatilis Hazlett 9313/CU 

Carex aurea Nuttall Hazlett 9289lCU 

Carex brevior (Dewey) Mackenzie Hogan l276ICU 

Carex filifolia Nuttall Walter 1 724/CS 

Carex inops L. Bailey ssp. heliophila (Mackenzie) Crins. 

[C. pensylvanica Lam. ssp. heliophila, C. heliophila] (reported) 

soapweed, Spanish bayonet 

arrowhead 

broadleaf arrowhead 

spiderwort 

swollen rush 

water sedge 

golden sedge 

sedge 

threadleaf sedge 

Pennsylvania sedge, sun sedge 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: MONOCOTS (Cont'd.) COMMON NAME 

Cyperaceae (Cont'd.) 

Carex lanuginosa Michaux (reported) 

Carex nebrascensis Dewey Hazlett 7789lCS , 9352lCU 

Carex praegracilis W. Boott. Hazlett 931 2lCS 

Carex rossii F. Boott Hazlett 10334lCS 

Carex simulata Mackenzie Yeatts 3265lKHD 

Carex stenophylla Wahlenberg [C. stenophylla ssp. eleocharis, 

C. duriscula, C. eleocharis] Hazlett 97101CU 

Cyperus acuminatus Torrey & Hooker ex Torrey Lederer 4514lCU 

Eleocharis acicularis (L.) Roemer & Schultes Lederer 4494lCU 

Eleocharis palustris (L.) Roerner & Schultes [E. macrostachya] 

Hazlett 101 02lCU 

Eleocharis parvula (Roemer & Schultes) Link [E. coloradoensis] 

Moir 696131lCU 

Schoenoplectus acutus (Muhlenberg ex Bigelow) Love & Love var. 

acutus [Scirpus, Schoenoplectus lacustris ssp. acutus] Sawyer 49lCS 

Schoenoplectus pungens (M. Vahl.) Palla [Scirpus pungens var. 

polyphyllus, Scirpus americanus] Hazlett 9290lCU 

Schoenoplectus saximontanus (Fernald) Raynal [Scirpus] 

Hazlett 9345lCU 

Schoenoplectus tabernaemontani (K.C. Grnel.) Palla [Schoenoplectus 

lacustris ssp. creber, Scirpus tabernaemontani, Scirpus validus] 

Hazlett 9329lCU 

lridaceae 

Sisyrinchium idahoense Bicknell var. occidentale (Bicknell) 

D. Henderson Hazlett 9292lCS 

Sisyrinchium montanum Greene Hazlett 10028lCU 

Juncaceae 

Juncus balticus Willdenow var. montanus Engelmann [J. arcticus 

var. balticus, J. ater] Harrington 107lCS 

Juncus longistylis Torrey var. longistylis Hazlett 92911CU 

Juncus nodosus L. Neese & Andrews 16027/CS, Hazlett 9325lCU 

Juncus torreyi Coville Hazlett 7838lCS & 9354lCU 

Juncaginaceae 

Triglochin maritimum L. Hazlett 10025/CS, 9336lCU 

Liliaceae 

Allium textile A. Nelson & Macbride [Alliaceae] Walter 1752lCS 

Leucocrinum montanum Nuttall sand lily Sawyer 101 CS 

Maianthemum stellatum (L.) Link [Convallariaceae: Smilacina] 

Hazlett 7702lCS 

Zigadenus venenosus S. Watson var. gramineus (Rydberg) Walsh ex 

Peck [Melanthiaceae: Toxicoscordion] Hazlett 7624lCS (at CPER) 

Poaceae 

*Aegilops cylindrica Host [Cylindropyrum] wheat fields 

*Agropyron cristatum (L.) Gaertner Klein 3265lCS 

*Agrostis stolonifera L. Sawyer 285lCS 

Andropogon gerardiivitrnan Johnson 251lCS (Weld) 

Andropogon hallii Hackel Christ 1257lCS 

Aristida purpurea Nuttall var. fendleriana (Steudel) Vasey 

[A. fendleriana] Johnson 187lCS 

Aristida purpurea Nuttall var. longiseta (Steud.) Vasey 

[A. longiseta Steud. ] Wilken & Painter 133671CS 

Beckmannia syzigachne (Steudel) Fernald ssp. baicalensis 

(Kuznetzow) Koyarna & Kuwano Sawyer 326lCS 

Woolly sedge 

Nebraska sedge 

blackcreeper sedge 

Ross' sedge 

lookalike sedge 

narrowleaf sedge 

acuminate flatsedge 

slender spikerush 

common spikerush 

dwarf spikerush 

hardstern bulrush 

common threesquare 

annual bulrush 

softstern bulrush, tule 

Idaho blue-eyed grass 

blue-eyed grass 

Baltic rush 

rush 

knotted rush 

Torrey's rush 

arrowgrass 

wild onion 

spikenard 

death carnas 

jointed goatgrass, jointgrass 

crested wheatgrass 

redtop bentgrass 

big bluestem 

sand bluestem 

Fendler's three-awn 

purple three-awn, no-eatum 

American sloughgrass 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: MONOCOTS (Cont'd.) COMMON NAME 

Poaceae (Cont'd.) 

Bouteloua curtipendula (Michaux) Torrey var. curtipendula 

Johnson 1991CS 

Bouteloua gracilis (Humboldt, Bonpland & Kunth) Lagasca 

[Chrondosum] Klein 31 7lICS 

Bouteloua hirsuta Lagasca var. hirsuta [Chondrosum] 

Hazlett 10295/CS 

Bouteloua simplex Lagasca [B. prostratum, Chondrosum prostratum] 

Johnston 1 135lUNC 

*Bromus commutatus Schrader Snyder 129lCS 

*Bromus inermis Leysser [Bromopsis] Johnson 1061CS 

*Bromus japonicus Thunberg Hazlett 7740lCS 

*Bromus tectorum L. [Anisantha] Walter 17641CS 

Buchloe dactyloides (Nuttall) Engelmann Hazlett 76231CS (at CPER) 

Calamovilfa longifolia (Hooker) Scribner var. longifolia 

Hazlett 75621CS (at CPER) 

*Cenchrus longispinus (Hackel) Fernald Hazlett 100821CU 

*Dactylis glomerata L. Sawyer 2011CS 

Distichlis spicata (L.) Greene var. stricta [D. stricta] Hazlett 93141CU 

*Echinochloa crusgalli (L.) Beauvois var. crusgalli Klein 3204/CS, 

Hazlett 10201 /CU 

Elymus canadensis L. var. canadensis Klein 32921CS 

Elymus elymoides (Rafinesque) Swezey [Sitanion hystrix] 

Walter 1720/CS 

Elymus lanceolatus (Scribner &Smith) Gould ssp. albicans 

Barkwort h & Dewey [Agropyron albicans, A. griffithsii, E, albicans] 

Neely 3594lRMH 

Elymus lanceolatus (Scribner & Smith) Gould ssp. lanceolatus 

[Agropyron dasystachyum & A. riparium] Hazlett 92951CU 

Elymus trachycaulis (Link) Gould ex Shinners ssp. trachycaulus 

[Agropyron] Costello et al. 4236/CS 

* Thinopyrum intermedium (Host) Barkworth & Dewey 

[Elytrigia intermedia, Agropyron intermedium] (expected) 

*Thinopyrum ponticum (Podpera) Barkworth & Dewey 

[Agropyron elongatum, Elymus elongatus var. ponticus] 

Johnson 2691CS 

*Elytrigia repens (L.) Nevski var. repens [Agropyron & Elymus] 

Johnson 1011CS 

*Eragrostis cilianensis (Allioni) Mosher Hazlett 100391CU 

Hordeum jubatum L. [Critesion] Klein 31 951CS 

Hordeum pusillum Nuttall [Critesion] Hazlett 9288lCU 

Koeleria macrantha (Ledebour) Schultes [K. cristata ] Sawyer 2951CS 

Leersia oryzoides (L.) Swartz Hazlett 93841CU 

*Leptochloa fascicularis (Lam.) A. Gray Wingate 4533lKHD 

Monroa squarrosa (Nuttall) Torrey [Munroa] Sawyer 4461CS 

Muhlenbergia asperifolia (Nees & Meyer ) Parodi Hazlett 75721CS 

(at CPER) 

Muhlenbergia cuspidata (Torrey) Rydberg Hazlett 103351CS 

Muhlenbergia racemosa (Michaux) Britton et a/. Johnson1 251CS 

Muhlenbergia torreyi (Kunth.) A.S. Hitchcock ex Bush 

Lederer 45271CU 

Oryzopsis hymenoides (Roemer & Schultes) Ricker ex. Piper 

[Achnatherum & Stipa hymenoides] Klein 32751CS & Hazlett 92861CU 

*Panicurn capillare L. Sawyer 4471CS 

*Panicurn miliaceum L. Wingate 4095lKHD (Weld) 

Panicum virgatum L. Hazlett 94221CU 

Pascopyron smithii (Rydberg) Love [Agropyron & Elymus] 

Walter 1703lCS 

sideoats grama 

blue grama 

hairy grama 

mat grama, six-weeks gramma 

cheatgrass, brome grass 

smooth brome 

Japanese brome or chess 

cheatgrass, downy brome or chess 

buffalo grass 

prairie sandreed 

field sandbur 

orchard grass 

saltgrass 

barnyard grass, watergrass 

Canada wildrye 

squirrreltail 

thickspike wheatgrass 

thickspike wheatgrass 

slender wheatgrass 

intermediate wheatgrass 

tall wheatgrass 

quackgrass 

stinkgrass 

foxtail barley 

little barley 

junegrass 

rice cutgrass 

bearded sprangletop 

false buffalo grass 

scratchgrass 

plains rnuhly 

marsh muhly 

ring muhly, ring grass 

Indian ricegrass 

common witchgrass, 

ticklegrass 

proso millet, broom corn millet 

switchgrass 

western wheatgrass 

14 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: MONOCOTS (Cont'd.) COMMON NAME 

Poaceae (Cont'd.) 

'Phalaris arundinacea L. [Phalaroides] Hazlett 9889lRMH (Weld) 

'Phleum pratense L. Sawyer 3481CS 

Poa arida Vasey Costello 4235lCS 

*Poa pratensis L. [P. agassizensis] Moir 692840lCU 

Poa secunda J. Presl. [P. sandbergii] Sawyer 2351CS 

*Polypogon monspeliensis (L.) Desfontaines 

Hazlett 75141CS (at CPER) 

* Psathyrostachys juncea (Fischer) Nevski [Elymus junceus] 

Sawyer 951CS 

Puccinellia nuttalliana (Schultes) A. S. Hitchcock [P. airoides] 

Klein 3209lCS 

Schedonnardus paniculatus (Nuttall) Trelease Lederer 44911CU 

Schizachyrium scoparium (Michaux) Nash var. scoparium 

[Andropogon] Klein 3308lCS 

Secale cereale L. 

*Setaria pumila (Poiret) Roemer & Schultes [S. glauca, S. lutescens] 

Weber 130041CU (Weld) 

*Setaria viridis (L.) P. Beauvois Johnson 329lCS 

Spartina gracilis Trinius Hazlett 101 40lCU 

Spartina pectinata Link Hazlett 9337lCU 

Sphenopholis obtusata (Michaux) Scribner Hanson 4lCU 

Sporobolus airoides (Torrey) Torrey Hazlett 78391CS 

Sporobolus cryptandrus (Torrey) A. Gray Walter 1761 ICS 

Stipa comata Trinius & Ruprecht [Hesperostipa] Walter 1721lCS 

Stipa robusta (Vasey) Scribner [Achnantherum] Hazlett 75961CS 

(at CPER) 

Stipa viridula Trinius [Nassella] Costello 4237lCS 

Vulpia octoflora (Walter) Rydberg [Festuca] Walter 1728lCS 

Pontederiaceae 

Heteranthera limosa (Swartz) Willdenow Hazlett 93051CU 

Potamogetonaceae 

Potamogeton diversifolius Rafinesque Hazlett 931 2lCU 

Potamogeton foliosus Rafinesque ssp. foliosus 

Hazlett 101 27lCU & 101 87lCU 

Potamogeton pectinatus L. [Coleogeton pectinatus] (expected) 

Typhaceae 

Typha angustifolia L. BrunquisttCS 

Typha latifolia L. Johnson 2291CS 

reed canary grass 

timothy 

plains bluegrass 

Kentucky bluegrass 

Sandberg bluegrass 

rabbitfoot grass 

Russian wildrye 

American alkali-grass 

tumblegrass 

little bluestem 

wild rye, volunteer rye 

yellow foxtail 1 bristlegrass 

green foxtail I bristlegrass 

alkali cordgrass 

prairie cordgrass, cut-throat grass 

prairie wedge scale 

alkali sacaton 

sand dropseed, go-back grass 

needle-and-thread 

sleepygrass 

green needlegrass 

sixweeks fescue 

mud plantain 

waterthread pondweed 

leafy pondweed 

fennel-leaf pondweed 

narrow-leaved cattail 

broad-leaved cattail 

ANGIOSPERMS: DICOTS 

Amaranthaceae 

*Amaranthus albus L. Neese & Andrews 160551CS 

*Amaranthus blitoides S. Watson [A. graecizans] Klein 32551CS 

'Amaranthus retroflexus L. Klein 32451CS 

Anacardiaceae 

Rhus aromatica Aiton var. trilobata (Nuttall ex Torrey & Gray) 

A. Gray [ R. trilobata Nuttall] Hazlett 7827lCS 

Toxicodendron rydbergii (Small ex Rydberg) G reene [Rhus radicans] 

Johnson 2071CS 

Apiaceae 

Berula erecta (Hudson) Coville Hazlett 100291CU 

*Conium maculatum L. Johnson 109lCS 

tumble pigweed 

prostrate pigweed 

redroot pigweed 

skunkbush sumac, 

quailbush sumac 

poison-ivy 

water parsnip 

poison hemlock 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Apiaceae (Cont'd.) 

Cymopterus acaulis (Pursh) Rafinesque var. acaulis Hazlett l452ICS 

Cymopterus montanus Nuttall ex. Torrey & Gray Hazlett 14511CS 

Lomatium nuttallii (Gray) J.F. Macbride [Aletes] Hazlett 90821CS 

Lomatium orientale Coulter & Rose (expected) 

Musineon divaricatum (Pursh) Nuttall ex Torrey & Gray var. divaricatum 

Sawyer 311CS 

Musineon tenuifolium (Nuttall ex Torrey & Gray) Coulter & Rose [Aletes] 

Hazlett 78081CS 

Apocynaceae 

Apocynum cannabinum L Hazlett 771 61CS 

Asclepiadaceae 

Asclepias arenaria Torrey Hazlett 77991CS 

Asclepias pumila (Gray) Vail Sawyer 3371CS 

Asclepias speciosa Torrey Sawyer 2671CS 

Asclepias stenophylla A. Gray Hazlett 781 31CS 

Asclepias viridiflora Rafinesque Wilken et al. 12389/CS, Hazlett 93551CU 

Asteraceae 

Achillea millefolium L, ssp. lanulosa (Nuttall) Piper [A. lanulosa] 

Klein 32231CS 

*Acosta diffusa (Lamarck) Sojak [Centaurea] Hazlett 100571CU 

*Acroptilon repens (L.) DC. [Centaurea] Costello 42581CS 

Ambrosia acanthicarpa Hooker Klein 3249lCS 

*Ambrosia artemisiifolia L. Hazlett 1 01 331CU 

Ambrosia psilostachya DC. var. coronopifolia (Torrey & Gray) Farwell 

Klein 32061CS 

Ambrosia tomentosa Nuttall Klein 32051CS 

Ambrosia trifida L. Neese & Andrews 160281CS 

Antennaria parvifolia Nuttall Hazlett 91211CU 

*Arctiurn minus (J. Hill) Bernhardi Johnson 3161CS 

*Artemisia absinthium L. Hazlett 101 39/CU 

*Artemisia biennis Willdenow var. biennis Hazlett 7590/CS, Klein 32971CS 

Artemisia campestris L. ssp. caudata (Michaux) Hall & Clements 

[Oligosporus caudatus] Klein 3287lCS 

Artemisia dracunculus L. ssp. glauca (Pallas ex. Willdenow) 

Hall & Clernents [Oligosporus] Hazlett 100991CU 

Artemisia filifolia Torrey [Oligosporus] Hazlett 75 1 21CS (at CP ER) 

Artemisia frigida Willdenow Klein 321 51CS 

Artemisia ludoviciana Nuttall ssp. ludoviciana Klein 32991CS 

Aster ascendens Lindley [A. chilensis & Virgulasterj Hazlett 78351CS 

Aster ericoides L. var. stricticaulis (Torrey & Gray) Gates 

[Virgulus] Neese & Andrews 160581CS 

Aster falcatus Lindley var. commutatus (Torrey & Gray) A. Jones 

[Virgulus] (expected) 

Aster falcatus Lindley var. falcatus [Virgulus] Klein 33001CS 

Aster laevis L. var. geyeri A. Gray Hazlett 93801CU (Weld) 

Aster lanceolatus Willdenow ssp. hesperius (Gray) 

Semple & Chmielewski [A. hesperius] 

Bidens cernua L. Hazlett 78691CS 

Bidens comosa (A. Gray) Wiegand Hazlett 101 351CU 

Bidens frondosa L. Neese & Andrews 160971CS 

Brickellia eupatorioides L. var. corymbulosa (Torrey & Gray) Shinners 

[Kuhnia] Hazlett 76931CS 

Brickellia grandiflora (Hooker) Nuttall Hazlett 771 7/CS 

*Carduus nutanz L. Hazlett 77301CS 

wild parsley 

biscuit root 

Nuttall's biscuitroot, dog parsley 

northern Idaho biscuitroot 

leafy wild parsley 

slender wild parsley 

Indian hemp, dogbane 

sand milkweed 

plains milkweed 

showy milkweed 

narrow-leaved milkweed 

green milkweed 

western yarrow 

diffuse knapweed 

Russian knapweed 

annual bursage 

short ragweed 

western ragweed 

perennial bursage, 

poverty weed 

giant ragweed 

pussytoes 

common burdock 

absinthe wormwood 

biennial wormwood 

western sagewort 

wild taragon, silky wormwood 

sand sagebrush 

fringed sagewort 

white sage 

Chile aster 

white heath aster 

cluster aster 

cluster aster 

blue aster 

Siskiyou aster 

bur-marigold, 

nodding beggarticks 

Straw-stem beggarticks 

Devil's beggarticks 

false boneset 

brickellia 

nodding thistle, musk thistle 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Asteraceae (Cont'd.) 

Chrysothamnus nauseosus (Pallas ex Pursh) Britton ssp. graveolens 

(Nuttall) Piper [Ericameria nauseosa var. glabrata] Klein 3173lCS 

Chrysothamnus nauseosus (Pallas ex Pursh) Britton ssp. nauseosus 

[Ericameria nauseosa var. nauseosa] Sawyer 4331CS 

'Cichoriurn intybus L. Sawyer 3841CS 

*Cirsium arvense (L.) Scopoli [Breea] Sawyer 4331CS 

Cirsium canescens Nuttall Hazlett 98641CU (Logan) 

Cirsium flodmanii (Rydberg) Arthur Hazlett 1 001 91CU 

Cirsium ochrocentrum A. Gray Wilken & Walter 123661CS 

Cirsium undulatum (Nuttall) Sprengel Walter 17091CS 

'Conyza canadensis (L.) Cronquist Klein 31941CS 

Crepis runcinata (James) Torrey & Gray ssp. runcinata [Psilochenia] 

Hazlett 931 61CU 

Dyssodia papposa (Ventenat) A. S. Hitchcock Hazlett 7597/CS, 

Klein 32461CS 

Erigeron bellidiastrum Nuttall var. bellidiastrum Hazlett 92991CU 

Erigeron canus A. Gray Hazlett 77441CS 

Erigeron lonchophyllus Hooker Hazlett 9327lCU 

Erigeron pumilus Nuttall var. pumilis Walter 17481CS 

Evaxprolifera Nuttall ex DC. Hazlett 93071CU 

Gnaphalium palustre Nuttall Hazlett 93261CU 

*Gnaphalium uliginosum L. Hazlett 94251CU 

Grindelia squarrosa (Pursh) Dunal var. squarrosa 

[G. serrulata var serrulata] Klein 31 961CS 

Gutierrezia sarothrae (Pursh) Britton & Rusby Walter I77OlCS 

Helianthus annuus L. Klein 3285lCS 

Helianthus petiolaris Nuttall var. petiolaris Klein 331 IICS 

Helianthus pumiius Nuttall Klein 32691CS 

Heterotheca villosa (Pursh) Shinners var. minor Semple 

[Chrysopsis, H. villosa var, hispida] Klein 31811CS 

Heterotheca villosa (Pursh) Shinners var. villosa [Chrysopsis] 

Klein 32841CS 

Hymenopappus filifolius Hooker var. polycephalus (Oesterhout) 

6. Turner Hazlett 7548/CS, Klein 31 90ICS 

Hymenopappus tenuifolius Pursh Hazlett 7734lCS 

Iva axillaris Pursh Klein 31751CS 

'Iva xanthifolia Nuttall ICyclanchaenal Klein 32761'2s 

*Lactuca serriola L. Hazlett 991 3lRMH 

*Lactuca oblongifolia [Lactuca tatarica ssp. pulchella] 

Hazlett 7841/CS, Klein 3202lCS 

Liatris punctata Hooker var. punctata Klein 32371CS 

Lygodesmia juncea (Pursh) D. Don ex. Hooker Walter 1776lCS 

Machaeranthera canescens (Pursh) Gray ssp. canescens 

Wilken 139201CS 

Machaeranthera grindelioides (Nuttall) S hinners var. grindelioides 

[Haplopappus nuttallir] Hazlett 77361CS 

Machaeranthera pinnatifida (Hooker) Shinners ssp. pinnatifida var. 

pinnatifida [Haplopappus spinulosus var. spinulosus] Kle i n 32681CS 

Machaeranthera tanacetifolia (Humboldt, Bonpland & Kunth) Nees 

Hazlett 101 001CU 

Nothocalais cuspidata (Pursh) Greene Harrington 921CS 

*Onopordum acanthium L. Hazlett 100611CU 

Parthenium alpinum (Nuttall) Torrey & Gray [Bolophyta] Harmon 881 OICS 

Picradeniopsis oppositifolia (Nuttall) Rydberg Klein 32611CS 

Pseudognaphalium stramineum (Humboldt, Bonpland & Kunth) 

W.A. Weber [Gnaphalium stramineurn & Gnaphalium chilense] 

Hazlett 101 12lCU 

rabbitbrush, rubber rabbitbrush 

rabbitbrush 

chichory 

Canadian thistle 

Platte thistle 

Flodman's thistle 

yellowspine thistle 

wavy-leaf thistle 

horseweed 

hawk's-beard 

fetid marigold, 

prairiedog weed 

sand fleabane daisy 

fleabane daisy 

fleabane daisy 

fleabane daisy 

rabbit-tobacco 

diffuse cudweed 

low cudweed 

rosinweed, gumweed 

snakeweed 

common sunflower 

plains sunflower 

foothill's sunflower 

bristly hairy goldenaster 

hairy goldenaster 

hymenopappus 

hymenopappus 

poverty weed 

marsh elder 

prickly lettuce 

blue lettuce 

gay-feather, blazing star 

skeletonweed 

hoary aster 

rayless goldenweed 

goldenweed 

Tahoka daisy, tansy aster 

nothocaulis 

scotch thistle 

alpine feverfew 

bahia 

cudweed 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Asteraceae (Cont'd.) 

Ratibida columnifera (Nuttall) Wooton & Standley Klein 31 82ICS 

Rayjacksonia annua (Rydberg) Hartman & Lane [Machaeranthera annua, 

M. phyllocephala & Haplopappus annuus] Hazlett 10022lCU 

*Scorzonera laciniata L. Hazlett 9709lRMH 

Senecio canus Hooker [Packera] Hazlett 77231CS 

Senecio spartioides Torrey & Gray Hazlett 7849/CS, Klein 32421CS 

Senecio tridenticulatus Rydberg [Packera] Sawyer 361CS 

Shinnersoseris rostrata (A. Gray) Tomb Hazlett 78441CS 

Solidago canadensis L. var. gilvocanescens Rydberg Klein 32981CS 

Solidago missouriensis Nuttall var. missouriensis Hazlett 103311CS 

Solidago mollis Bartling Neese 161 211CS 

Solidago rigida L. var. humilis Porter [Oligoneuron] Hazlett 93561CU 

*Sonchus asper (L.) J. Hill Hazlett 101 101CU 

*Sonchus oleraceus L. Sawyer 41 11CS 

Stenotus armerioides Nuttall var. armerioides [Haplopappus] 

Hazlett 91 261CU 

Stephanomeria pauciflora (Torrey) A. Nelson Klein 31 78ICS 

*Taraxacum officinale G. H. Weber Sawyer 71CS 

Tetraneuris acaulis (Pursh) Greene [Hymenoxys acaulis var. acaulis] 

Sawyer 371CS 

Thelesperma filifolium (Hooker) A. Gray var. intermedium 

(Rydberg) Shinners Hazlett 7532/CS, 9846lRMH 

Thelesperma megapotamicum (Sprengel) Kuntze var. megapotamicum 

Hazlett 7795/CS, Klein 33011CS 

Townsendia exscapa (Richardson) Porter Hazlett 9123lCU 

Townsendia grandiflora Nuttall Sawyer 493lCS 

Townsendia hookeri Beaman Wilken & Donahue 125141CS 

*Tragopogon dubius Scopuli Sawyer 821CS 

* Tragopogon porrifolius L. (reported) 

* Verbesina encelioides (Cavanilles) Bentham & Hooker ex Gray 

ssp. exauriculata Robinson & Greenman [Ximenesia] Hazlett 75131CS 

*Xanthium strumarium L. var. canadense (Miller) Torrey & Gray 

Klein 32931CS 

Boraginaceae 

Cryptantha cana (A. Nelson) Payson [Oreocarya] Hazlett 77501CS 

Cryptantha celosioides (Eastwood) Payson [Oreocarya] 

Hazlett 77811CS & 9156lCS 

Cryptantha cmerea (Greene) Cronquist var. jamesii Cronquist 

[Cryptantha jamesii, Oreocarya suffruticosa] Hazlett 7765/CS, 

Sawyer 731CS 

Cryptantha crassisepala (Torrey & Gray) Greene var. crassisepala 

Johnston 32lUNC (Weld) 

Cryptantha fendleri (Gray) Greene Hazlett 9035lCU 

Cryptantha minima Rydberg Klein 32471CS 

Cryptantha thyrsiflora (Greene) Payson [Oreocaya] 

Hazlett 75951CS & 98481CU 

*Cynoglossum officinale L. Hazlett 7559/CS, Sawyer 1371CS 

Lappula occidentalis (S. Watson) Greene var. cupulata (Gray) Higgins 

[L. texana, L. redowskiivar. cupulata & L. marginata] Hazlett 9296lCU 

Lappula occidentalis (S. Watson) Greene var. occidentalis [L. redowskii] 

Walter 17451CS 

Lithospermum incisum Lehmann Walter 1766lCS 

Mertensia lanceolata (Pursh) A. DC. var. lanceolata 

Hazlett 78021C5, Sawyer 611CS 

Plagiobothrys scouleri (Hooker & Arnott) Johnston 

ssp. penicillatus G reene Love [P. scouleri var. hispidulus] 

Hazlett 93241CU 

prairie coneflower 

annual goldenweed 

false salsify, cut-leaf salsify 

gray ragwort 

groundsel 

groundsel 

shinnersoseris 

Canada goldenrod 

prairie goldenrod 

soft goldenrod 

rigid goldenrod 

prickly sow thistle 

common sow thistle 

goldenweed 

wire lettuce 

common dandelion 

stemless bitterweed 

annual greenthread 

greenthread 

Easter daisy 

Easter daisy 

Easter daisy 

goat's beard, western salsify 

goatsbeard 

cowpen daisy 

cocklebur 

cryptantha, mountain cat's-eye 

cryptantha, buttecandle 

James' cryptantha 

annual cryptantha 

Fendler's cryptantha 

annual cryptantha 

cryptantha, calcareous 

cat's-eye 

hound's tongue 

stickseed 

stickseed 

puccoon 

bluebells 

popcorn flower 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Brassicaceae 

*Alyssum desertorum Stapf Hazlett 761 1/CS (at CPER) 

*Alyssum parviflorum Bieberstein [A. minus] Hazlett 90941CS 

*Camelha microcarpa Andrzejowski ex DC. Hazlett 7806lCS 

*Capsella bursa-pastoris (L.) Medicus Johnson 9/CS 

*Cardaria chalepensis (L.) Handel-Mazetti (expected) 

*Chorispora tenella (Pallas) DC. Hazlett 761 0/CS (Weld) 

*Conringia orientalis (L.) Dumont de Cours Hazlett 9885lCU 

Descurainia incana (Bernhardi ex Fischer & Meyer) Dorn 

ssp. incana [D. richardsonirl Hazlett 77541CS 

Descurainia pinnata (Walter) Britton ssp. filipes (Gray) Peck 

Hazlett 10058/CS 

Descurainia pinnata (Walter) Britton ssp. nelsonii (Rydberg) Peck 

Osterhout 5495lRM 

*Descurainia sophia (L.) Webb Hazlett 7755/CS, Sawyer 134ICS 

Draba reptans (Lamarck) Fernald Hazlett 9125lCU 

Erysimum asperum (Nuttall) DC. Sawyer 3071CS 

*Lepidium campestre (L.) R. Brown [Neolepia] Hazlett 91 1 3/CS 

Lepidium densiflorum Schrader var. densiflorum Klein 3248lCS 

Lesquerella alpina (Nuttall ex. Torrey & Gray) S. Watson var. alpina 

Hazlett I O296ICS 

Lesquerella arenosa (Richardson) Rydberg var. arenosa 

Hazlett 771 2/CU 

Lesquerella ludoviciana (Nuttall) S. Watson 

Hazlett 7761 ICS, Sawyer 691CS 

Rorippa curvipes Greene var. curvipes Hazlett 9892lRM (Weld) 

Rorippa palustris (L.) Besser (expected) 

Rorippa sinuata (Nuttall in Torrey & Gray) A. S. Hitchcock Sawyer 76/CS 

* Sisymbrium altissimum L. Walter 1 706/CS 

Thelypodium integrifolium (Nuttall) Endlicher ssp. integrifolium 

Hazlett 951 8/CU 

* Thlaspi arvense L. Hazlett 7767/CS, Sawyer 181 ICS 

Thlaspi montanum L. var. montanum [Noccaea] Sawyer 240/CS 

Cactaceae 

Coryphantha vivipara (Nuttall) Britton & Rose var. vivipara Sawyer 1901CS 

Echinocereus viridiflorus Engelmann var. viridiflorus Sawyer 1 52/CS 

Opuntia fragilis (Nuttall) Haworth var. fragilis (expected) 

Opuntia macrorhiza Engelmann var. macrorhiza Hazlett 10297/CS 

Opuntia polyacantha Haworth var. polyacantha Sawyer 1 141CS 

Pediocactus simpsonii (Engelmann) Britton & Rose var. minor 

Sawyer l91ICS 

Capparaceae 

Cleome serrulata Pursh Walter 1713lCS 

Polanisia dodecandra (L.) DC. ssp. trachysperma (Torrey & Gray) lltis 

[P. trachysperma] Klein 3291 /CS 

Caprifoliaceae 

Symphoricarpos occidentalis Hooker Sawyer 404/CS 

Caryophyllaceae 

Arenaria hookeri Nuttall ssp. hookeri [Alsinaceae: Eremogone] 

Sawyer 402/CS 

Paronychia depressa Nuttall (Torrey & Gray) Nuttall ex A. Nelson 

[Alsinaceae] Hazlett 7725/CS, Sawyer 404lCS 

Paronychia sessiliflora Nuttall [Alsinaceae] Wilken & Lowery 12394lCS 

*Saponaria officinalis L. Sawyer 3921CS 

*Spergularia marina (L.) Grisebach [Alsiniaceae: S salina] 

Hazlett 9089/CS 

desert alyssum 

small alyssum 

smallseed falseflax 

shepherd's purse 

whitetop, hoary cress 

blue mustard 

hare's ear mustard 

tansy mustard 

tansy mustard 

tansy mustard 

flixweed 

whitlow grass 

western wallflower 

field peppergrass 

peppergrass 

bladderpod 

bladderpod 

bladderpod 

common yellowcress 

bog yellowcress 

spreading yellowcress 

tumble mustard 

thelypodium 

field pennycress 

mountain pennycress 

pincushion cactus 

hedgehog cactus 

little prickly pear 

plains prickly pear 

plains prickly pear 

nipple cactus 

Rocky Mountain beeplant 

clammyweed 

western snowberry, wolfberry 

tufted sandwort 

nailwort 

nailwort 

bouncing bet, soapwort 

sand spurry 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17.1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Chenopodiaceae 

Atriplex canescens (Purs h) Nuttall var. canescens Sawyer 277lCS 

Atriplex gardneri (Moquin) D. Dietr. var. utahensis (Jones) Dorn 

[A. nuttalli~] Hazlett 7867lCS 

*Atriplex heterosperma Bunge Hazlett 10298lCS 

*Atriplex rosea L. Hazlett 9649lCS (Weld) 

Atriplex subspicata (N uttall) Rydberg Hazlett 1 0030lCU 

*Chenopodium album L. Walter 1781lCS 

Chenopodium atrovirens Rydberg Hazlett 9440lCS 

Chenopodium berlandieri Moquin var. zschackei (Murr.) Murr. ex Aschers 

Hazlett 101 43lCS 

Chenopodium cycloides A. Nelson Clark 634lCU (Weld) 

Chenopodium desiccatum A. Nelson Klein 3251lCS & Hazlett 101 82lCU 

Chenopodium fremontii S. Watson var. fremontii Hazlett 7757lCS 

*Chenopodium glaucum L. Hazlett 101 19ICU 

Chenopodium hians Standley Wahl. 6487lRM (Larimer) 

Chenopodium incanum (S. Watson) Heller Wilken & Painter 13364lCS 

Chenopodium leptophyllum (Moquim) Nuttall ex Watson Hazlett 7791lC 

Chenopodium pratericola Rydberg Hazlett 10020lCU 

Chenopodium rubrum L. Hazlett 9428lCU 

Chenopodium subglabrum (S. Watson) A. Nelson (expected) 

Chenopodium watsonii A. Nelson Crawford 421lRM 

Corispermum hyssopifolium L. [C. americanum] Hazlett 101 83lCU 

Cycloloma atriplicifolium (Sprengel) Coulter Klein 3296lCS 

* Kochia scoparia (L.) Schrader [Bassia] Walter 1785lCS 

Krascheninnikovia lanata (Pursh) Meeuse & Smit 

[Ceratoides & Eurotia] Harrington 2239lCS 

Monolepis nuttalliana (Schultes) Greene Hazlett 9304lCU & 9882lRM 

*Salsola collina Pallas Hazlett 101 32lCU 

*Salsola tragus (L.) Celak. 

[S. australis, S. iberica, S. kalissp. tragus, S. pestifer] Klein 3258lCS 

Suaeda calceoliformis (Hooker) Moquin Hazlett 93221CU 

Suckleya suckleyana (Torrey) Rydberg Hazlett 101 81lCU 

Convolvulaceae 

Calystegia sepium (L.) R. Brown ssp. angulata (Brummitt) N. Holmgren 

Hazlett 9309lCU 

*Convolvulus arvensis L. Sawyer 446lCS 

* Evolvulus nuttallianus Schultes Sawyer 21 4lCS 

lpomoea leptophylla Torrey Wilken & Lowery 12375lCS 

Cuscutaceae 

Cuscuta indecora Choisy var. neuropetala (Engelmann) A. S. Hitchcock 

[Grammica] Christ 1252lCS (Weld) 

Elaeagnaceae 

*Elaeagnus angustifolia L. Sawyer 122lCS 

Elatinaceae 

Elatine triandra Schkuhr Hazlett 931 IICU 

Euphorbiaceae 

Croton texensis (Klotsch) Muller-Argoviensis in DC. Wilken 12270lCS 

Chamaesyce fendleri (Torrey & Gray) Small [Euphorbia] Hazlett 7574lCU 

Chamaesyce geyeri (Engelmann) Small [Euphorbia] 

Hazlett 7573lCS (at CPER) 

Chamaesyce glyptosperma (Engelmann) Small 

[Euphorbia] Klein 3176/CS, Hazlett 10091lCU 

Chamaesyce missurica (Rafinesque) Shinners [Euphorbia] Klein 3240lCS 

Chamaesyce serpyllifolia (Persoon) Small ssp. serpyllifolia [Euphorbia] 

Neese & AnJrews 16025lCS 

four-wing saltbush 

moundscale 

two-seed orach 

red orache, red scale 

spearscale 

lambsquarter 

mountain goosefoot 

lambsquarter 

sandhill goosefoot 

desert goosefoot 

Fremont's goosefoot 

oakleaf goosefoot 

goosefoot 

goosefoot 

goosefoot 

goosefoot 

alkali blite 

smooth goosefoot 

Watson's goosefoot 

hopleaf tickseed 

tumble ringweed 

kochia, alkaliweed 

winterfat 

poverty weed 

Russian thistle, tumbleweed 

Russian thistle, tumbleweed 

broom seepweed 

poison suckleya 

hedge bindweed 

field bindweed 

Nuttall's evolvulus 

bush morning-glory 

dodder, large alfalfa dodder 

Russian olive 

waterwort 

doveweed, Texas croton 

Fendler's spurge 

Geyer's spurge 

ridge-seeded spurge 

Missouri spurge 

thyme-leaved spurge 

20 USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Euphorbiaceae (Cont'd.) 

Chamaesyce stictospora (Engelmann) Small [Euphorbia] 

Neese & Andrews 16045lCS 

Euphorbia dentata (Michaux) Klotsch & Garcke [Poinsettia] 

Hazlett 7589lCS (at CPER) 

Euphorbia marginata Pursh [Agaloma] 

Euphorbia robusta (Engelmann) Small 

[E. brachyceras & Tithymalus brachyceras] Hazlett 7520/CS (at CPER) 

Fabaceae 

Amorpha fruticosa L. Hazlett 101 31 /CU 

Astragalus adsurgens Pallas var. robustior Hooker 

[A. laxmanii var. robustiofl Hazlett 75201CS 

Astragalus agrestis Douglas ex G. Don. Hazlett 7829lCS 

Astragalus bisulcatus (Hooker) A. Gray var. bisulcatus Walter 1749/CS 

Astragalus ceramicus Sheldon var. filifolius (A. Gray) F. J. Hermann 

Costello 4263/CS 

Astragalus crassicarpus Nuttall var. crassicarpus Sawyer 4221CS 

Astragalus drummondii Douglas ex Hooker Hazlett 751 5/CS 

Astragalus gilviflorus Sheldon var. gilviflorus [Orophaca triphylla] 

Harmon 881 2/CS 

Astragalus gracilis Nuttall Hazlett 7733/CS, Walter 1787/CS 

Astragalus kentrophyta A. Gray var. kentrophyta 

Hazlett 76011CS (at CPER) 

Astragalus lotiflorus Hooker Hazlett 77311CS & 9310/CU 

Astragalus missouriensis Nuttall var. missouriensis 

Hazlett 751 8/CS (at CPER) 

Astragalus mollissimus Torrey var. mollissimus Klein 3177112s 

Astragalus pectinatus (Hooker) Douglas in Hooker Costello 4262/CS 

Astragalus plattensis Nuttall (reported) 

Astragalus sericoleucus A. Gray [Orophaca sericea] 

Hazlett 7522/CS (at CPER) 

Astragalus spatulatus Sheldon Hazlett 9131/CU 

Astragalus tenelus Pursh Hazlett 7847/CS & 9856lCU 

Astragalus tridactylicus A. Gray [Orophaca] Neely 2806lCS 

Dalea candida Willdenow var. oligophylla (Torrey) Shinners Klein 3294lCS 

Dalea cylindriceps Barneby Lederer 451 7/CU 

Dalea purpurea Ventenat var. purpurea Hazlett 7742/CS 

Glycyrrhiza lepidota Pursh Hazlett 7608/CS, Klein 3214lCS 

Hedysarum boreale Nuttall ssp. boreale Hazlett 9157/CS 

Lathyrus polymorphus Nuttall ssp. incanus 

(Smith & Rydberg) C. L. Hitchcock Hazlett 7625lCS (at CPER) 

Lathyrus polymorphus Nuttall ssp. polymorphus (expected) 

Lupinus argenteus Pursh ssp. argenteus Sawyer 100/CS & 

Hazlett 10052lCU 

Lupinus plattensis Watson (expected) 

Lupinus pusillus Pursh ssp. pusillus Walter 17311CS 

* Medicago lupulina L. Hazlett 7798/CS 

*Medicago sativa L. Sawyer 31 7/CS 

*Melilotus albus Medicus Hazlett 10053/CU 

* Melilotus officinalis (L.) Lam. Sawyer 21 /CS 

Oxytropis lambertii Pursh Wilken 12300dCS 

Oxytropis multiceps Nuttall Hazlett 9127/CU 

Oxytropis sericea Nuttall var. sericea Hazlett 7737/CS 

Pediomelum esculentum (Pursh) Rydberg [Psoralea] Harrington 4056/CS 

Pediomelum hypogaeum (Nutt. ex Torrey & Gray) Rydberg var. hypogaeum 

[Psoralea] Hazlett 9308lCU 

Psoralidium lanceolatum (Pursh) Rydberg [Psoralea] Hazlett 7748lCS 

Psoralidum tenuiflorum (Pursh) Rydberg [Psoralea] Walter 1707/CS 

mat spurge 

toothed spurge 

snow-on-the-mountain 

perennial spurge 

false indigo 

standing milk-vetch 

field milk-vetch 

two-grooved milk-vetch 

painted milk-vetch 

ground-plum 

Drummond milk-vetch 

plains orophaca, 

plains milkvetch 

slender milk-vetch 

Nuttall's kentrophyta 

lotus milk-vetch 

Missouri milk-vetch 

woolly milk-vetch 

tine-leaved milk-vetch 

Platte milk-vetch 

silky orophaca 

draba milk-vetch 

pulse milk-vetch 

three-leaved milk-vetch 

white prairie clover 

massive spike prairie clover 

purple prairie clover 

wild licorice 

sweet broom 

hoary vetchling 

hoary vetchling 

silvery lupine 

Platte lupine 

small lupine 

black medick 

alfalfa 

white sweet clover 

yellow sweet clover 

purple locoweed 

dwarf locoweed 

white locoweed 

breadroot, prairie turnip, tipsin 

little breadroot 

lemon scurf-pea 

scurfy-pea 

USDA Forest Sewice Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Fabaceae (Cont'd.) 

Sophora nuttalliana B. Turner [Vexibia] Sawyer 81CS 

Thermopsis rhombifolia (Nuttall ex Pursh) Richardson var. rhombifolia 

Hazlett 76161CS (at CPER) 

* Trifolium fragiferum L. Hazlett 90841CS 

*Trifolium repens L. Johnston 195lUNC 

Vicia americana Muhlenberg var. minor Hooker 

Hazlett 75241CS (at CPER) 

Gentianaceae 

*Centaurium pulchellum (Swartz) Druce Hazlett 93471CU 

Geranianceae 

*Erodium cicutarium (L.) L'Heritier ex Ait. Johnson 371CS 

Grossulariaceae 

Ribes aureum Pursh var. villosum [R. odoratum] Sawyer 31CS 

Ribes cereum Douglas Hazlett 77901CS 

Haloragaceae 

Myriophyllum sibiricum Komarov [ M. exalbescens] 

Hazlett 78501CS. Osterhout 1041lRM 

Hydrophyllaceae 

*Ellisia r~yctelea (L.) L. Hazlett 75281CS (at CPER) 

Phacelia hastata Douglas ex Lehmann var. hastata 

Hazlett 75851CS (at CPER) 

Lamiaceae 

Hedeoma drummondii Bentham Wilken & Lowery 123791CS 

Hedeoma hispidum Pursh Hazlett 100961CU 

Lycopus americanus Muhlenberg ex W. Barton 

Hazlett 78361CS & 101 361CU 

Lycopus asper Greene Ramaley 151 95lCU (Weld) 

*Marrubium vulgare L. Klein 32711CS 

Mentha arvensis L. Hazlett 77881CS 

*Salvia reflexa Hornemann Hazlett 7842/CS, Klein 32311CS 

Scutellaria brittoniiT. C. Porter Sawyer 45/CS 

Stachys palustris L. ssp. pilosa (Nuttall) Epling [S. pilosa] 

Hazlett 93791CU (Weld) 

Lemnaceae 

Lemna minor L. [Lemna turionifera] Harrington 5046/CS, Hazlett 93891CU 

Lemna valdiviana Philippi Harrington 35091CS (Weld) 

Linaceae 

Linum lewisii Pursh var. lewisii [Adenolinum & L. perenne var. lewisli] 

Johnston 436lUNC 

Linum puberulum (Engelmann) Heller [Mesynium] Hazlett 77621CS 

Linum rigidum Pursh var. rigidum [Mesynium] Hazlett 77451CS 

Loasaceae 

Mentzelia albicaulis (Douglas ex Hooker) Douglas ex Torrey & Gray 

[Acrolasia] Hazlett 77011CU 

Mentzelia decapetala (Pursh) Urban & Gilg [Nuttallia] Klein 32861CS 

Mentzelia nuda (Pursh.) Torrey & Gray var. stricta (Osterhout) 

Harrington [Nuttallia nuda] Klein 32781CS 

white loco 

prairie buck bean, yellow pea 

strawberry clover 

white clover 

American vetch 

centaury 

crane's bill 

golden currant, anise bush 

western red currant 

water milfoil 

waterpod 

lanceleaf phacelia 

Drummond's false pennyroyal 

rough false pennyroyal 

American bugleweed 

rough bugleweed 

horehound 

field mint 

lanceleaf sage, chia 

Britton's skullcap 

hedge nettle, marsh betony 

duckweed 

duckweed 

blue flax 

plains flax 

yellow flax 

whitestem blazing star 

ten-petal mentzelia, blazing star 

mentzelia, blazing star 

Lythraceae 

*Ammannia robusta Heer & Regel Hazlett 93431CU toothcup 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17.1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Malvaceae 

*Abutilon theophrasti Medicus Hazlett 99801RM 

*Hibiscus trionum L. Hazlett 901 51CS (Weld) 

'Malva neglecta Wallroth Johnson 31 5lCS 

*Malva parviflora L. KlingerICS 

Sphaeralcea coccinea (Pursh) Rydberg var. coccinea Walter 171 01CS 

Nyctaginaceae 

Abronia fragrans Nuttall ex. Hooker var. fragrans Klein 32891CS 

Mirabilis hirsuta (Pursh) MacMillan [Oxybaphus] 

Hazlett 7739lCS & 10036lCU 

Mirabilis linearis (Pursh) Heimerl [Oxybaphus] Klein 32451CS 

Mirabilis nyctaginea (Michaux) MacMillan [Oxybaphus] Hazlett 78141CS 

Tripterocalyx micranthus (Torrey) Hooker [Abronia] Hazlett 93831CU 

Onagraceae 

Calylophus lavandulifolius (Torrey & Gray) Raven 

Hazlett 78041CS & 9854lCU 

Calylophus serrulatus (Nuttall) Raven Hazlett 7555lCS (at CPER) 

Epilobium ciliatum Raf inesque var. ciliatum Hazlett 1 002 1 ICS 

Epilobium ciliatum Rafinesque var. glandulosum (Lehm.) Dorn 

Hazlett 93801CS 

Gaura coccinea Nuttall ex Pursh Walter 171 IICS 

Gaura parviflora Douglas Hazlett 7579/CS(at CPER) 

Oenothera albicaulis Pursh Klein 3244lCS 

Oenothera caespitosa Nuttall ssp. caespitosa Hazlett 77531CS 

Oenothera canescens Torrey & Fremont Hazlett 781 21CS & 10088lCU 

Oenothera coronopifolia Torrey & Gray Walter 171 81CS 

Oenothera flava (A. Nelson) Garrett Klein 3233lCS 

Oenothera latifolia (Rydberg) Munz [O. pallida] Hazlett 77201CS 

Oenothera villosa Thunberg ssp. strigosa (Rydberg) Dietrich & Raven 

Klein 3295/CS, Hazlett 78541CS 

Orobanchaceae 

Orobanche fasciculata Nuttall [Aphyllon] Hazlett 78071CS 

Orobanche ludoviciana Nuttall ssp. ludoviciana Costello 42561CS 

Orobanche multiflora Nuttall Hazlett 10134/CU, Osterhout 985lRM (Logan) 

Papaveraceae 

Argemone polyanthemos (Fedde) G. B. Ownbey Walter 171 21CS 

Plantaginaceae 

Plantago eriopoda Torrey Hazlett 91 041CS & 94271CS 

* Plantago major L. Sawyer 2481CS 

Plantago patagonica Jacqui n var. patagonica [P. purshii] Walter 1 7391CS 

Polemoniaceae 

lpomopsis congesta (Hooker) V. Grant ssp. congesta Dodds 21 161CU 

lpomopsis laxiflora (Coulter) V. Grant Klein 32431CS 

lpomopsis spicata (Nuttall) V. Grant var. spicata Hazlett 77321CS 

Leptodactylon caespitosum Nuttall Wilken & Painter 13785lCS 

Microsteris gracilis (Douglas ex Hooker) Greene var. humilor (Hooker) 

Cronquist [Phlox gracilis] Hazlett 91 161CU 

Phlox andicola Nuttall ex A. Gray Hazlett 77701CS & 98521CU 

Phlox hoodii Richardson ssp. hoodii Hazlett 91 1 OICU 

Phlox hoodii Richardson ssp. muscoides (Nuttall) Wherry 

[P. muscoides, P. bryoides] Hazlett 7726lCS 

velvet leaf 

flower-of-an-hour 

common mallow 

small-fruited mallow 

scarlet globernallow 

sand verbena 

hairy four-o'clock 

narrowleaf four-o'clock 

wild four o'clock 

sand puffs 

lavender-leaf primrose 

plains yellow primrose 

willow-herb 

willow-herb 

scarlet gaura 

velvetly gaura 

prairie evening primrose, 

gumbo lily 

gumbo evening primrose 

spotted evening primrose 

combleaf evening primrose 

yellow evening primrose 

pale evening primrose 

common evening primrose 

broomrape, cluster cancerroot 

broomrape, Louisiana cancerroot 

broom rape 

alkali plantain 

common plantain 

Indian woolly wheat, Pursh's plantain 

gilia 

gilia 

spike gilia 

clump slenderlobe 

microsteris 

plains phlox 

Hood's phlox 

moss phlox 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Polygonaceae 

Eriogonum alatum Torrey var. alatum [Pterogonum] Hazlett 9203lCS 

Eriogonum brevicaule Nuttall ssp. brevicaule Hazlett 7843lCS 

Eriogonum flavum Nuttall var. flavum Hazlett 9863lCU 

Eriogonum microthecum Nuttall var. effusum (Nuttall) Torrey & Gray 

[E. effusurn] Klein 31 71lCS 

Eriogonum pauciflorum Pursh var. gnaphalodes (Bentham in Hooker) 

Reveal Hazlett 781 1iCS 

Eriogonum umbella tum To rrey var. umbella tum Sawyer 1 97/CS 

Polygonurn amphibium L. var. emersum Michaux [Persicaria] 

Sawyer 309lCS 

*Polygonurn aviculare L [P. arenastrum] Walter 1758lCS 

Polygonum bicorne Rafinesque [ Persicaria] Hazlett 1 0200lCU 

Polygonum convolvulus L. [ Fallopia] Hazlett 7852lCS 

* Polygonum lapathifolium L. [Persicaria] Hazlett 101 20lCU 

'Polygonum pensylvanicum L. [Persicaria] Hazlett 7592lCS (at CPER) 

* Polygonum persicaria L. [Persicaria maculata] (reported) 

Polygonum ramosissimum Michaux Hazlett 101 96lCU (expected) 

Rumex altissimus Wood Sawyer l55lCS 

Rurnex aquaticus L. var. fenestratus (Greene) Dorn 

[R. aquaticus ssp. occidentalis & R. occidentalis] Hazlett 7853lCS 

*Rumex crispus L. Sawyer 388lCS 

Rumex maritimus L. [R. maritimus var. fueginus] Hazlett 1 0 1 93lCU 

Rumex salicifolius Weinmann var. mexicanus (Meissner) C. L. Hitchcock 

[R. salicifolius var. triangulivalvis, R. triangulivalvis] Hazlett 101 22lCU 

*Rumex stenophyllus Ledebour Hazlett 101 94lCU 

Rumex venosus Pursh Sawyer 35lCS 

Portulaccaceae 

*Portulaca oleracea L. Hazlett 101 85lCU 

Talinum parviflorum Nuttall Sawyer 31 3lCS 

Ranunculaceae 

Clematis ligusticifolia Nuttall in J. Torrey & A. Gray Johnson 165lCS 

Delphinium carolinianum Walter ssp. virescens (Nuttall) R. E. Brooks 

[Helleboraceae: D. virescens var. penardii] Hazlett 9294lCU 

Delphinium geyeri Greene [Helleboraceae] Hazlett 7792lCS 

Myosurus minimus L. Yeatts 3261lKHD 

Ranunculus aquatilis L. var. diffusus Withering 

[R. longirostris & R. subrigidus] Hazlett 101 44lCU 

Ranunculus cymbalaria Pursh [Halerpestes] Hazlett 931 5lCU 

Ranunculus gmelinii DC. Sawyer 1571CS 

Ranunculus macounii Britton Neese & Andrews 15994lCS 

Ranunculus sceleratus L. var. multifidus Nuttall [Hecatonia] 

Hazlett 7591lCS (at CPER) 

Thalictrum dasycarpum Fischer & Ave-Lallemant [Thalictraceae] 

Rosaceae 

Cercocarpus montanus Rafinesque var. montanus Hazlett 7766lCS 

Physocarpus rnonogynus (Torrey) Coulter Lederer 4509lCU 

Potentilla hippiana Lehm. ssp. effusa (Douglas ex Lehm.) Dorn 

[P. effusa] Hazlett 1 0040lCU 

* Potentilla norvegica L. Klein 3227lCS 

Potentilla paradoxa Nuttall [P. supina ssp. paradoxa] Hazlett 9332lCU 

Potentilla pensylvanica L. Hazlett 761 91CS & 93311CU 

Potentilla rivalis Nuttall Hazlett 9302lCU 

Prunus pumila L. var. besseyi (Bailey) Gleason [Cerasus, P. bessey~] 

Hazlett 7800lCS 

winged eriogonum 

shortstem eriogonum 

yellow buckwheat 

spreading buckwheat 

fewflower buckwheat 

sulfer buckwheat 

water smartweed 

prostrate knotweed 

pink smartweed 

climbing wild buckwheat 

pale smartweed 

Pennsylvania smartweed 

lady's thumb 

erect knotweed 

pale dock 

western dock 

curly dock 

golden dock 

beach dock 

narrowleaf dock 

wild begonia 

common purslane 

fameflower 

virgin's bower, western clematis 

plains larkspur, white larkspur 

Geyer's larkspur 

mouse-tail 

white water crowfoot 

shore buttercup I renocule 

cymbalaire 

small yellow buttercup 

Macoun's buttercup 

cursed crowsfoot 

purple meadow rue 

mountain mahogany 

ninebark 

cinquefoil 

Norwegian cinquefoil 

bushy cinquefoil 

cinquefoil 

brook cinquefoil 

sand cherry, dwarf cherry 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17.1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Rosaceae (Cont'd.) 

Prunus virginiana L. var. melanocarpa (A. Nelson) Sargent [Padus] 

Hazlett 7544lCS (at CPER) 

Rosa woodsii Lindley Hazlett 7866/CS 

Rubiaceae 

Galium aparine L. Hazlett 7793lCS 

Salicaceae 

Populus deltoides Bartram ex Marshall var. occidentalis Rydberg 

[P. deltoides ssp. monilifera, P. sargenti~] Sawyer 119lCS 

Salix amygdaloides Andersson Hazlett 7863lCS 

Salix exigua Nuttall var. exigua Hazlett 10033/CU 

Salix exigua Nuttall var. pedicellata (Andersson) Cronquist 

[S. exigua var. interior] Hazlett 92851CU 

Santalaceae 

Comandra umbellata (L.) Nuttall var. pallida (A. DC.) Jones Sawyer 11ICS 

Scrophulariaceae 

Agalinis tenuifolia (Vahl) Rafinesque 

var. parviflora (Nuttall) Pennell Neese & Andrews l6O32/CS 

Bacopa rotundifolia (Michaux) Wettstein Hazlett 7578/CS (at CPER) 

Castilleja sessiliflora Pursh Hazlett 7531 /CS (at CPER) 

Limosella aquatica L Hazlett 10098/CU, Klein 32351CS 

'Linaria dalmatica (L.) P. Miller ssp. dalmatica 

[L. dalmatica var. macedonica & L. genistifolia] Hazlett 7529lCS (at CPER) 

Orthocarpus luteus Nuttall Neese 15971/CS 

Penstemon albidus Nuttall Klein 3270lCS 

Penstemon angustifolius Nuttall ex Pursh var. angustifolius Sawyer 44/CS 

Veronica americana Schweinitz ex Bentham Hazlett 7705lCS 

*Veronica anagallis-aquatica L. Neese & Andrews 16065lCS 

'Veronica catenata Pennell [L. salina] Harrington & E. C. Smith 578lCS 

*Veronica peregrina L. ssp. xalapensis (Humboldt, Bonpland & Kunth) 

Pennell Hazlett 91 19/CU 

*Veronica persica Poiret [Pocilla biloba] (expected) 

Solanaceae 

*Datura stramonium L. 

Yycium barbarum L. [L. halimifolium] Hazlett 7692lCS (at CPER) 

Physalis hederifolia Gray var. comata (Rydberg) Waterfall Johnson 200/CS 

Physalis pumila Nuttall ssp. hispida (Waterfall) Hinton [P. hispida] 

Hazlett 7622/CS 

Physalis virginiana Miller Hazlett 7865lCS 

Quincula lobata (Torrey) Rafinesque [Physalis lobata] 

Hazlett 7832/CS, 9853lCU 

Solanum interius Rydberg [S. americanum, S. nigrum var. virginianum] 

Hazlett 7784lCS 

*Solarium heterodoxum Dunal Sawyer 23/CS 

*Solanurn physalifolium Rusby [S. physalifolium var. nitidibaccatum & 

S. sarrachoides] Hazlett 10060/CU 

Solanum rostratum Dunal Sawyer 31 1/CS 

*Solanurn triflorum Nuttall Hazlett 7523/CS, Klein 32571CS 

Tamaricaceae 

*Tamarix ramosissima Ledebour [T. chinensis] Hazlett 9090/CS 

Ulmaceae 

Celtis reticulata Torrey [C. laevigata var. reticulata] Hazlett 7803lCS 

*Ulmus pumila L. Hazlett 102991CS 

chokecherry 

western wild rose 

catchweed bedstraw 

plains cottonwood 

peachleaf willow 

foothills sandbar willow 

plains sandbar willow 

bastard toadflax 

gerardia 

water hyssop 

downy paintbrush 

mudwort 

dalmatian toadflax 

owl clover 

white beardtongue 

narrow beardtongue 

American brooklime, speed well 

speedwell 

speedwell 

purslane speedwell 

bird's eye speedwell 

jimson weed 

matrimony vine, teavine 

prairie or ivy-leaved ground cherry 

prairie ground cherry 

Virginia ground cherry 

purple ground cherry 

plains black nightshade 

nightshade 

viscid nightshade 

buffalo bur, stickerweed 

cut-leaved nightshade 

salt cedar 

netleaf hackberry 

Siberian elm 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 
ANGIOSPERMS: DICOTS (Cont'd.) COMMON NAME 

Urticaceae 

Parietaria pensylvanica Muhlenberg ex Willdenow Hazlett 7709lCS pellitory 

Urtica dioica L. ssp. gracilis (Aiton) Selander stinging nettle 

[U. gracilis ssp. gracilis, U. dioica var. procera] Hazlett 77871CS 

Verbenaceae 

Phyla cuneifolia (Torrey) Greene [Lippia] Hazlett 781 91CS 

*Verbena bracteata Lagasca & Rodriguez Walter 1753/CS 

Verbena stricta Ventenat Lederer 45121CU 

Violaceae 

Viola nuttallii Pursh Sawyer 1 SICS 

Vitaceae 

Vitis riparia Michaux (reported) 

Zygophyllaceae 

*Tribulus terrestris L. Hazlett 7577lCS (at CPER) 

wedgeleaf fog-fruit 

prostrate vervain 

hoary vervain 

yellow prairie violet 

wild grape, riverbank grape 

puncture vine, tackbur, caltrop 

USDA Forest Service Gen. Tech. Rep. RMRS-GTR-17. 1998 

RMRS 

ROCKY MOUNTAIN RESEARCH STATION 

The Rocky Mountain Research Station develops scientific information 

and technology to improve management, protection, and use of forests 

and rangelands. Research is designed to meet the needs of National 

Forest managers, federal and state agencies, public and private 

organizations, academic institutions, industry, and individuals. 

Studies accelerate solutions to problems involving ecosystems, 

range, forests, water, recreation, fire, resource inventory, land 

reclamation, community sustainability, forest engineering technology, 

multiple use economics, wildlife and fish habitat, and forest insects and 

diseases. Studies are conducted cooperatively, and applications can be 

found worldwide. 

Research Locations 

Flagstaff, Arizona 

Fort Collins, Colorado* 

Boise, ldaho 

Moscow, ldaho 

Bozeman, Montana 

Missoula, Montana 

Lincoln, Nebraska 

Reno, Nevada 

Albuquerque, New Mexico 

Rapid City, South Dakota 

Logan, Utah 

Ogden, Utah 

Provo, Utah 

Laramie, Wyoming 

* Station Headquarters, 240 West Prospect Road, Fort Collins, CO 80526 

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its 

programs and activities on the basis of race, color, national origin, gender, 

religion, age, disability, political beliefs, sexual orientation, and marital or familial 

status. (Not all prohibited bases apply to all programs.) Persons with disabilities 

who require alternative meansfor communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA1s TARGET Center at (202) 

720-2600 (voice and TDD). 

To file a complaint of discrimination, write USDA, Director, Office of Civil 

Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW, 

Washington, D.C. 20250-941 0, or call (202) 720-5964 (voice or TDD). USDA is 

an equal opportunity provider and employer. 

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