Crepis intermedia A. Gray. 1

NOMENCLATURE

Limestone hawksbeard (Crepis intermedia A. 

Gray), belongs to the Asteraceae family and the 

Psilochaenia section of the Crepis genus (Bogler 

2006; Enke 2009). Nomenclature in this review 

follows Bogler (2006).

NRCS Plant Code. CRIN4 (USDA NRCS 2019).

Subtaxa. Crepis intermedia Nuttall var. intermedia 

(A. Gray) Jepson.

Synonym. Psilochenia intermedia (A. Gray) W.A.

Common Names. Limestone hawksbeard, gray 

hawksbeard, small-flower hawksbeard (USDA FS 

1937; Bogler 2006; Welsh et al. 2016; Hitchcock 

and Cronquist 2018).

Chromosome Number. Chromosome numbers 

are: 2n = 33, 44, 55, 88 (Babcock and Stebbins 

1938; Bogler 2006). 

Hybridization. Limestone hawksbeard is a 

polyploid species that resulted from hybrid 

combinations involving two or three of the 

following hawksbeard species (Crepis spp.): 

tapertip hawksbeard (C. acuminata), largeflower 

hawksbeard (C. occidentalis), slender hawksbeard 

(C. exilis), Modoc hawksbeard (C. modocensis), 

or nakedstem hawksbeard (C. pleurocarpa) 

(Babcock and Stebbins 1938; Cronquist et al. 

1994). Ongoing gene flow and intergradations are 

reported in areas where limestone hawksbeard 

occurs with any of the aforementioned 

hawskbeards or bearded hawksbeard (C. 

barbigera) (Breitung 1957; Whitton et al. 2008). 

DISTRIBUTION

Limestone hawksbeard is a western species 

occurring in southern British Columbia, Alberta, 

Saskatchewan, and south to northern New Mexico, 

Arizona, and central California (Bogler 2006; 

USDA NRCS 2019). It occurs primarily east of 

the Cascade Mountains in the Pacific Northwest 

LIMESTONE HAWKSBEARD

Crepis intermedia A. Gray

Asteraceae – Aster family

Corey L. Gucker and Nancy L. Shaw | 2020

ORGANIZATION

Recommendations/guidelines, wildland restoration successes/

failures.

Names, subtaxa, chromosome number(s), hybridization.

Range, habitat, plant associations, elevation, soils. 

Life form, morphology, distinguishing characteristics, reproduction.

Growth rate, successional status, disturbance ecology, importance to 

animals/people.

Current or potential uses in restoration.

Seed sourcing, wildland seed collection, seed cleaning, storage, 

testing and marketing standards.

Recommendations/guidelines for producing seed.

Recommendations/guidelines for producing planting stock.

Primary funding sources, chapter reviewers. 

Bibliography.

Select tools, papers, and manuals cited.
2 Crepis intermedia A. Gray

(Hitchcock and Cronquist 2018). Populations are 

most abundant in northern California and southern 

Oregon, becoming local and infrequent eastward 

(Babcock and Stebbins 1938).

In a study that coupled herbarium records and 

ecological niche modelling to describe the 

suitable climates for Great Basin forb species, 

increasing summer precipitation had a negative 

effect on the potential climate suitability for 

limestone hawksbeard in western sagebrush 

(Artemisia spp.) ecosystems (Barga et al. 2018). 

Habitat and Plant Associations. Limestone 

hawksbeard is one of the more widely distributed 

hawksbeard species (Babcock and Stebbins 

1938). Because it exhibits characteristics of its 

parent species, it is preadpated to changing 

conditions and capable of colonizing new habitats. 

In some parts of its range, this process is 

considered aggressive. Although most common 

on arid, well-drained slopes at the lower edge of 

the ponderosa pine (Pinus ponderosa) forests in 

bunchgrass and sagebrush communities (Figs. 1 

and 2), limestone hawksbeard has ascended 

higher into the glaciated valleys of the central 

Sierra Nevada Mountains than any other 

hawksbeard (Babcock and Stebbins 1938).

Figure 1. Limestone hawksbeard growing in a big sagebrush/

grassland community in Utah. Photo: US Forest Service, 

Rocky Mountain Research Station, Provo Shrub Sciences 

Laboratory (USFS RMRS PSSL). 

Limestone hawksbeard occupies rocky ridges, 

dry slopes, and open forests throughout its 

range. Common plant associates include 

Sandberg bluegrass (Poa secunda), wheatgrasses 

(Elymus and Pseudoroegneria spp.), buckwheat 

(Eriogonum spp.), lupine (Lupinus spp.), arrowleaf 

balsamroot (Balsamorhiza sagitatta), sagebrush, 

pinyon (Pinus spp.), juniper (Juniperus spp.), oak 

(Quercus spp.), and mixed conifers (Standley 1921; 

USDA FS 1937; Munz and Keck 1973; Bogler 2006; 

Lesica 2012; Welsh et al. 2016). 

Limestone hawksbeard was described as 

common and showy in dry basin big sagebrush 

(A. tridentata subsp. tridentata) shrublands 

occurring from 2,500 to 2,900 feet (760-

880 m) in the Glass Mountain region of Mono 

County, California (Horner 2001). In vegetation 

descriptions of south-central Nevada, including 

the Nevada Test Site, limestone hawksbeard 

occupied an elevation range of 6,000-8,500 feet 

(1,800-2,600 m). It occurred in singleleaf pinyonUtah juniper/big sagebrush (P. monophylla-J. 

osteosperma/A. tridentata) and curl-leaf mountain 

mahogany (Cercocarpus ledifolius)/big sagebrush 

communities and white fir (Abies concolor) forests 

(Beatley 1976).

Elevation. The elevation range for limestone 

hawksbeard is 1,500 to 12,800 feet (460-3,900 m) 

(Munz and Keck 1973; Bogler 2006). In Utah it is 

5,000 to 8,450 feet (1,525-2,575 m) (Welsh et al. 

2016), and in California it is 1,500 to 10,500 feet 

(460-3,200 m) (Munz and Keck 1973).

Soils. Populations are often associated with 

well-drained, stony soils (USDA FS 1937), but 

texture and parent material can vary. Limestone 

hawksbeard occurred in serpentine soils in the 

Wentachee and Blue Mountains of Washington 

and Oregon (Babcock and Stebbins 1938). In 

California’s Lassen County, populations occupied 

heavy clay loams near Susanville and light clay 

loams near Horse Lake. Soils at both sites were 

nearly neutral with pH of 6.6 to 6.8. In the Sierra 

Nevada Mountains, limestone hawksbeard was 

frequent in basaltic and granitic soils (Babcock 

and Stebbins 1938).

Although more common at lower elevations, 

limestone hawksbeard is found in the bristlecone 

pine (Pinus aristata) zone (9,500-10,000 ft [2,900-

3,000 m]) of the White Mountains in California. In 

this area, limestone hawksbeard was restricted 

to sandstone substrates and did not occur on 

dolomite or granite (Table 1). Sandstone soils 

had greater clay and available moisture and were 

closer to neutral pH than the dolomite and granite 

soils. Average annual precipitation in the study 

area from 1953 to 1962 was 12.5 inches (318 mm) 

(Wright and Mooney 1965).

Table 1. Soil characteristics of three substrates in the 

bristlecone pine zone of the White Mountains in California. 

Limestone hawksbeard was restricted to sandstone soils 

(Wright and Mooney 1965).

Soil characteristics Sandstone Dolomite Granite

Sand (%) 63 64 82

Silt (%) 33 34 15

Clay (%) 4 2 3

Avail moisture (%) 25 20 16

pH 6 8 6
Crepis intermedia A. Gray. 3

In the Jackson Hole region of Wyoming, limestone 

hawksbeard was common in big sagebrush 

communities. Soils in these communities had 

about 1 inch (2.5 cm) of litter accumulation, an 

A horizon of fine sandy loam, which was about 3 

inches deep (8 cm), followed by a thin B horizon of 

coarse sandy loam. Beneath the A and B horizons 

was a very coarse gravelly and stony mass of 

parent till 10 feet (3 m) or more deep (Reed 1952).

Figure 2. Limestone hawksbeard growing in a big sagebrush 

community in Utah. Photo: USFS RMRS PSSL. 

DESCRIPTION

Limestone hawksbeard is a perennial from a 

slender to stout taproot and simple to branched 

caudex (Fig. 3) (Bogler 2006). The caudex, 

covered by dead basal leaves, gives rise to one 

or two erect, 10 to 28-inch (25-70 cm) tall stems 

(Babcock and Stebbins 1938; Bogler 2006; Welsh 

et al. 2016). Stems are branched, often covered 

in fine soft hairs, and exude a milky juice when 

damaged (Bogler 2006; Lesica 2012; Welsh et al. 

2016).

Plants produce basal and stem leaves. Stem 

leaves have long petioles that clasp the stems 

(Babcock and Stebbins 1938; Bogler 2006; Welsh 

et al. 2016). Lower leaves measure 4 to 16 inches 

(10-40 cm) long and 0.8 to 3.5 inches (2-9 cm) 

wide (Munz and Keck 1973; Bogler 2006). They are 

elliptic, pointed at the apex, and pinnately lobed 

half to three quarters of the way to the midvein. 

The triangular lobes are sometimes toothed 

(Babcock and Stebbins 1938; Bogler 2006; Lesica 

2012; Welsh et al. 2016). Leaves, like the stems, 

are sparsely to strongly gray tomentose (Fig. 4) 

(Babcock and Stebbins 1938).

Figure 3. Robust limestone hawksbeard plant growing in Utah. 

Photo: USFS RMRS PSSL. 

Figure 4. Limestone hawksbeard in flower. Note the 

indeterminate flowering and gray tomentose look of the 

stems and leaves. Photo: USFS RMRS PSSL. 

Plants produce 10 to 60 flower heads in mostly 

flat-topped, compound inflorescenses (Fig. 4) 

(Babcock and Stebbins 1938; Bogler 2006). 

Flower heads contain 7 to 16 florets (Babcock and 

Stebbins 1938; Munz and Keck 1973). Involucres 

are narrowly cylindrical, 0.4 to 0.8 inch (1-2 cm) 

tall and less than a third as wide. The outer bracts 

are less than half as long as the inner bracts 

(Babcock and Stebbins 1938; Hitchcock and 
4 Crepis intermedia A. Gray

Cronquist 2018). Corollas are yellow and 0.5 to 

1.2 inches (1.4-3 cm) long (Babcock and Stebbins 

1938; Munz and Keck 1973). Anther tubes when 

well developed are about 0.2-inch (0.5 cm) long 

and typically abort without producing pollen. 

Style branches are 2.5 to 3.5 mm long (Babcock 

and Stebbins 1938). The fruit is a subcylindric 

achene 0.2 to 0.4 inch (0.6-1 cm) long with tapered 

ends. It is yellow to brown with 10 to 12 ribs and 

a dusky white pappus 0.3 to 0.4 inch (0.7-1 cm) 

long (Babcock and Stebbins 1938; Bogler 2006; 

Lesica 2012). Limestone hawksbeard represents 

a somewhat peculiar group of polyploid 

apomicts, which combine the features of multiple 

species including tapertip hawksbeard, Modoc 

hawksbeard, nakedstem hawksbeard, and slender 

hawksbeard (Babcock and Stebbins 1938). For 

a description of the many forms and their likely 

parentage, see Babcock and Stebbins (1938).

Reproduction. Limestone hawksbeard is selfincompatible and facultatively apomictic with a 

low frequency of sexual reproduction. Most seed 

is produced asexually, while plants retain the 

ability to produce sexual offspring (Stebbins and 

Jenkins 1939). Apomixis is the method of seed 

production that substitutes sexual reproduction 

with an asexual reproductive process not involving 

fertilization, resulting in the production of clones 

(Stebbins 1941). Insect damage of seeds is 

common (Babcock and Stebbins 1938).

To assess the evidence of sexual reproduction 

and gene flow, researchers evaluated patterns 

of genetic variation at a contact zone for three 

hawksbeard species in Union County, Oregon. 

All but 1 of 13 limestone hawksbeard plants 

sampled produced pollen, but pollen stainability 

was low (32.5%). They found 10 genotypes in the 

13 sampled plants using 70 variable randomly 

amplified polymorphic DNA (RAPD) loci. Limestone 

hawksbeard and slender hawksbeard were 

genetically diverse with overlapping patterns 

of variation suggesting gene flow. Phylogenetic 

and compatibility analyses indicated that 

recombination had influenced patterns of 

genotypic diversity within the samples, and 

sufficient pollen was available for fertilization of 

some ovules (Whitton et al. 2008).

Pollination. Limestone hawksbeard flowers are 

common in June and July (BLM SOS) but may also 

be seen in May and August (Munz and Keck 1973; 

Bogler 2006). Although pollination is not required 

for seed production, plants attract generalist bees 

and those that specialize on sunflower family 

(Asteraceae) flowers (St. John and Tilley 2012). 

Mason bees (Osmia spp.) were the dominant 

hawksbeard visitors at field evaluations of 19 

locations in 5 states (Cane 2005).

ECOLOGY

In general, hawksbeard seedlings rapidly develop 

a long slender taproot but aboveground biomass 

production is slower. Plants are considered 

long-lived and take 2 to 3 years to produce seed 

(Babcock and Stebbins 1938; James et al. 2009; 

Ogle et al. 2012). The limited number of ecological 

studies available suggest that limestone 

hawksbeard is found on recently disturbed sites 

and at some sites it is an aggressive invader 

(Dalzell 2004; Babcock and Stebbins 1938).

Seed and Seedling Ecology. Limestone 

hawksbeard seedlings grew slowly in a study 

comparing the growth rates of native and 

nonnative species in increased nitrogen (N) 

environments (James et al. 2009). Native soil and 

native and nonnative seedlings were harvested 

from the Northern Great Basin Experimental 

Range west of Burns, Oregon. Except for arrowleaf 

balsamroot seedlings, which were obtained 

commercially. Seedling growth was evaluated 

after 5 weeks of growth outdoors in large pots 

(10-inch [25 cm] diameter, 12 inches [30 cm] 

deep). Growth and biomass measurements 

were averaged across treatments. Treatments 

varied the arrangement, but not the amount, of 

added N, which was mixed throughout the soil or 

delivered in 2 or 4 patches. The RGR of limestone 

hawksbeard averaged a little less than 0.01 g/g/

day, which was less than that of all nonnative 

forbs and most native bunchgrasses evaluated. 

Root biomass of limestone hawksbeard averaged 

a little less than 1 g, which was less than that of 

all nonnative forbs and bunchgrasses. The root 

mass ratio (biomass allocated to roots relative 

to total plant biomass) of limestone hawksbeard 

averaged 0.7 g/g, which was greater than that of all 

nonnative forbs. All species evaluated, including 

limestone hawksbeard, acquired more N when it 

was available in patches than when it was mixed 

throughout the soil profile (James et al. 2009).

Disturbance Ecology. In two studies, limestone 

hawksbeard was reported on recently burned 

sites. In southern Idaho, limestone hawksbeard 

occurred but was not common on a site burned in 

August 5 to 6 years earlier. The burned area was 

aerial seeded with a mix of native and nonnative 

species that did not include limestone hawksbeard 

(Dalzell 2004). On the North Rim of Grand Canyon 

National Park, Arizona, limestone hawksbeard 

occurred in vegetation that burned frequently 

(found on up to 22% of plots) but not in long 

unburned vegetation (Laughlin et al. 2004).
Crepis intermedia A. Gray. 5

Limestone hawksbeard plays a role in tying up 

nutrients from deep soil layers in the spring. In a 

sagebrush community in eastern Oregon (mean 

10.6 inches [270 mm] annual precipitation), 

researchers evaluated growth and N uptake of 

native forbs (limestone hawksbeard and nineleaf 

biscuitroot [Lomatium triternatum]), bunchgrasses 

(bluebunch wheatgrass [Pseudoroegnaria spicata], 

squirreltail [Elymus elymoides], and Sandberg 

bluegrass), and nonnative annual grasses 

(cheatgrass [Bromus tectorum] and medusahead 

[Taeniatherum caput-medusae]). Comparisons 

were made to assess community resistance to 

invasion. Leaf biomass production of limestone 

hawksbeard peaked in May at about 2 g/plant. 

Forbs had higher rates of leaf production early in 

the growing season but a shorter period of growth 

than native bunchgrasses. Forbs and annual 

grasses acquired a significantly greater proportion 

of N in April than in May (P < 0.001). Native 

bunchgrasses acquired a significantly greater 

proportion of N in May than in April (P < 0.001). 

Forbs acquired most N in April from deep (6.7-

8.6 in [17-22 cm]) soil layers, and bunchgrasses 

acquired most N in May from shallow layers, 

suggesting both groups play a role in decreasing 

N available to native annual grasses. Experimental 

removal of forbs did not result in a significant 

increase in the density of medusahead (P < 0.05), 

but bunchgrass removal did. This was largely 

attributed to high bunchgrass biomass, which 

provided for the largest sequestration of N (James 

et al. 2008).

Wildlife and Livestock Use. Hawksbeard 

species are components of greater sage-grouse 

(Centrocercus urophasianus) habitats (Lambert 

2005) and important food sources for birds (Young 

and Young 1986; Pennington et al. 2016).

Livestock feed on limestone hawksbeard, which 

is considered fairly palatable to cattle and highly 

palatable to domestic sheep. Palatability is highest 

in spring and early summer and overgrazing by 

sheep is possible (USDA FS 1937).

Hawksbeard plants are important in the diets of 

greater sage-grouse hens and chicks (Drut et al. 

1994; Pennington et al. 2016). In southeastern 

Oregon sagebrush communities, hawksbeard 

plants were consumed by greater sage-grouse 

hens in greater proportion than they were 

available in the vegetation (P < 0.05) (Barnett and 

Crawford 1994). Diets of 42 hens were evaluated 

over a 5-week period in big sagebrush and 

low sagebrush (Artemisia arbuscula) habitats 

preceding incubation (4 March-8 April) in 1990 

and 1991. Hawksbeard leaves together with 

sagebrush, desertparsley (Lomatium spp.), and 

long-leaf phlox (Phlox longifolia) made up 84 to 

95% of diets. Hawksbeard’s highest frequency in 

crops was 62%, and it was 14% of the relative dry 

weight consumed. Hawksbeard plants contained 

25 to 30% crude protein, 0.78% calcium, and 

0.5% phosphorous (Barnett and Crawford 1994). 

Greater sage-grouse chicks (average 6 weeks 

old) in southeastern Oregon also consumed 

hawksbeard in a proportion that exceeded 

availability. The highest frequency of hawksbeard 

in the chick’s diets was 69% (Drut et al. 1994).

Limestone hawksbeard also provides habitat for 

insects, which are also important components of 

bird diets. Limestone hawksbeard is a larval host 

for a moth, Sparganothis tunicana (Tortricidea) 

(Gilligan and Epstein 2012).

REVEGETATION USE 

Although its use in revegetation has been 

limited, limestone hawksbeard is an important 

wildlife species (Drut et al. 1994; Pennington et 

al. 2016) and has several growth characteristics 

that suggest the species should persist once 

established (Babcock and Stebbins 1938). 

Although seedling growth is slow, individual plants 

are relatively long-lived (Shock et al. 2018). Longdistance dispersal is facilitated by the production 

of light-weight seeds with pappi that are carried by 

the wind (Figs. 5 and 7) (Bogler 2006).

Figure 5. Limestone hawksbeard producing seed in California. 

Photo: US Department of the Interior, Bureau of Land 

Management, Seeds of Success (USDI, BLM, SOS) CA 170.

DEVELOPING A SEED SUPPLY

For restoration to be successful, the right seed 

needs to be planted in the right place at the right 

time. Coordinated planning and cooperation 

is required among partners to first select 
6 Crepis intermedia A. Gray

appropriate species and seed sources and then 

properly collect, grow, certify, clean, store, and 

distribute seed for restoration (PCA 2015).

Developing a seed supply begins with seed 

collection from native stands. Collection sites are 

determined by current or projected revegetation 

requirements and goals. Production of nursery 

stock requires less seed than large-scale seeding 

operations, which may require establishment of 

agricultural seed production fields. Regardless of 

the size and complexity of any revegetation effort, 

seed certification is essential for tracking seed 

origin from collection through use.

Seed Sourcing. Because empirical seed zones are 

not currently available for limestone hawksbeard, 

generalized provisional seed zones developed 

by Bower et al. (2014), may be used to select and 

deploy seed sources. These provisional seed 

zones identify areas of climatic similarity with 

comparable winter minimum temperatures and 

aridity (annual heat:moisture index). In Figure 

6, Omernik Level III Ecoregions (Omernik 1987) 

overlay the provisional seeds zones to identify 

climatically similar but ecologically different 

areas. For site-specific disturbance regimes and 

restoration objectives, seed collection locations 

within a seed zone and ecoregion may be further 

limited by elevation, soil type, or other factors.

Figure 6. Distribution of limestone hawksbeard (black 

circles) based on geo-referenced herbarium specimens and 

observational data from 1881-2016 (CPNWH 2017; SEINet 

2017; USDI USGS 2017). Generalized provisional seed zones 

(colored regions) (Bower et al. 2014) are overlain by Omernik 

Level III Ecoregions (black outlines) (Omernik 1987; USDI 

EPA 2018). Interactive maps, legends, and a mobile app are 

available (USFS WWETAC 2017; www.fs.fed.us/wwetac/

threat-map/TRMSeedZoneMapper2.php?). Map prepared by 

M. Fisk, USDI USGS.

The Western Wildland Environmental Threat 

Assessment Center’s (USFS WWETAC 2017) 

Threat and Resource Mapping (TRM) Seed 

Zone application provides links to interactive 

mapping features useful for seed collection 

and deployment planning. The Climate Smart 

Restoration Tool (Richardson et al. 2019) can also 

guide restoration planning, seed collection, and 

seed deployment, particularly when addressing 

climate change considerations. 

Releases. As of 2020, there have been no 

limestone hawksbeard germplasm releases. 

Wildland Seed Collection. Seed is generally 

ripe once the dusky white pappus is visible in the 

seed head (St. John and Tilley 2012), which often 

occurs in June or July [USDI BLM SOS 2017]. 

Indeterminate seed set and the high probability 

of insect damage make planning, monitoring, and 

inspection important components of wildland 

seed collection for limestone hawksbeard (St. 

John and Tilley 2012).

Figure 7. Limestone hawksbeard seed head (left) and 

individual seeds with pappi (right). Photo: BLM SOS NV030 

(left), CA170 (right).

Wildland seed certification. Wildland seed 

collected for direct sale or for establishment 

of agricultural seed production fields should 

be Source Identified through the Association 

of Official Seed Certifying Agencies (AOSCA) 

Pre-Variety Germplasm Program that verifies 

and tracks seed origin (Young et al. 2003; 

UCIA 2015). For seed that will be sold directly 

for use in revegetation, collectors must apply 

for certification prior to making collections. 

Applications and site inspections are handled by 

the state where collections will be made. Details 

of the collection site and procedures are required 

for seed that will be used for planting agricultural 

seed fields or nursery propagation. Seed collected 

by most public and private agencies following 

established protocols may enter the certification 

process directly without certification agency site 
Crepis intermedia A. Gray. 7

inspections when protocols include collection of 

all data required for Source Identified certification 

(see Agricultural Seed Field Certification section). 

Wildland seed collectors should become 

acquainted with state certification agency 

procedures, regulations, and deadlines in the 

states where they collect. Permits or permission 

from public or private land owners are required for 

all collections.

Collection timing. A good indicator of seed 

ripeness is visibility of the pappi emerging from 

closed seed heads. Harvesting before pappus 

expression dramatically increases the amount 

of non-viable seed collected (St. John and Tilley 

2012). The Bureau of Land Management’s Seeds 

of Success field crews collected limestone 

hawksbeard from nine Idaho, Utah, Nevada, and 

California locations in 2009, 2010, and 2015 [USDI 

BLM SOS 2017]. Five of the collections were made 

in June and the other four in July. The earliest 

collection date was June 12, 2009, from 3,063 feet 

(934 m) in Ada County, Idaho. The latest collection 

date was July 15, 2015, from 7,840 feet (2,390 m) 

in Mono County, California [USDI BLM SOS 2017].

Figure 8. Limestone hawksbeard seed head and emerging 

insect larva. Photo: BLM SOS NV030.

Collection methods. Wildland seed can be 

collected by hand-stripping, using racquets to 

swat the seed heads over a collection hopper 

(St. John and Tilley 2012) or by clipping the seed 

heads (Fig. 8).

Several collection guidelines and methods should 

be followed to maximize the genetic diversity 

of wildland collections: collect seed from a 

minimum of 50 randomly selected plants; collect 

from widely separated individuals throughout a 

population without favoring the most robust or 

avoiding small stature plants; and collect from all 

microsites including habitat edges (Basey et al. 

2015). General collecting recommendations and 

guidelines are provided in online manuals (e.g. 

ENSCONET 2009; USDI BLM SOS 2016). As is the 

case with wildland collection of many forbs, care 

must be taken to avoid inadvertent collection of 

weedy species, particularly those that produce 

seeds similar in shape and size to those of 

limestone hawksbeard.

Post-collection management. Any vegetative 

material (e.g. stems, large leaves) should be 

removed from collected seed to reduce the 

moisture content and thus the potential for 

molding. Keep collections in dry, shaded locations, 

and do not allowed seed to overheat. Seed should 

be loosely packed in collection bags to provide 

good air circulation. Seed can be dried by laying 

it out in thin layers on screens in a well-ventilated, 

rodent-free area. Potential seed insects should 

be controlled using appropriate chemicals or by 

freezing the seed collection for 48 hours once 

thoroughly dried. Temporary storage prior to 

delivery at the seed extractory should be in a 

cool (< 50 °F [10 °C]), dry (< 35% relative humidity) 

location.

Seed Cleaning. Limestone hawksbeard seed 

can be cleaned and the pappus removed (Fig. 

9) following the guidelines for cleaning tapertip 

hawksbeard seed. Seed is first processed using a 

brush machine with the gate closed to remove the 

pappus. Final cleaning can be done using a multideck air screen cleaner with a 4-mm hole screen 

on top, 1.4-mm slot screen on the bottom, and 

light air (Tilley et al. 2012).

Seed Storage. Chromosome aberrations increase 

as seed of hawkbeard species ages (Nawaschin 

1933 cited in Harrington and Kozlowski 1972), but 

mutation rates are slower when seed is stored 

at low seed moisture and cool temperatures 

(Harrington and Kozlowski 1972).
8 Crepis intermedia A. Gray

Figure 9. Clean limestone hawksbeard seed. Photo: USFS 

RMRS PSSL.

Seed Testing. A tetrazolium chloride viability 

testing procedure was developed by the 

International Seed Testing Association for the 

hawksbeard genus (Moore 1985). Purity tests can 

be conducted using standard procedures. There 

is no Association of Official Seed Analysts (AOSA) 

rule for testing germination of Crepis species.

Germination. Although some seed germinates 

without stratification, best germination occurred 

after stratification in most studies. Germination of 

limestone hawksbeard increased with duration of 

cold stratification for seed collected from multiple 

populations near Reno and Carson City, Nevada. 

No after-ripening was required, and variation 

among populations was apparent. Seed was kept 

in the dark at 70 °F (21 °C) until germination trials 

began. Germination was 100% for seed that was 

stratified for 4 or 6 weeks at 36 °F (2 °C) before 

being germinated at 59 °F (15 °C) (Barga et al. 

2017; Leger and Barga 2017). At the Aberdeen, 

Idaho, Plant Materials Center (PMC), researchers 

suggested limestone hawksbeard seed would 

behave like tapertip hawksbeard seed that 

germinated at 11% without cold stratification and 

75% after 8 months of cold stratification (34 °F [1 

°C] in moist peat moss) (St. John and Tilley 2012).

However, in preliminary testing conducted at the 

National Tree Seed Laboratory (Dry Branch, GA), 

limestone hawksbeard seed germinated equally 

well with and without 4 weeks of cold stratification 

when germinated at 50, 59, or 68 °F (10, 15, or 20 

°C) (Karrfalt and Vankus 2012).

Wildland Seed Yield and Quality. Post-cleaning 

seed yield and quality of seed lots collected in the 

Intermountain region are provided in Table 2 (USFS 

BSE 2017). The results indicate that limestone 

hawksbeard seed can generally be cleaned to high 

levels of purity, but fill and viability of fresh seed is 

variable.

A wildland seed collection used to establish 

limestone hawksbeard production plots had 

similar pure live seed (84,506 seeds/lb [186,301/

kg) as that reported in Table 2, but viability was 

much lower (39%). Seed source was not reported 

(Shock et al. 2011). Limestone hawksbeard 

seed collected from populations at three sites 

in northern Nevada for a germination study also 

had weights (92,570-105,487 seeds/lb [204,078-

232,555/kg]) similar to that reported in Table 2 but 

viability was lower (42.5-72.5%) (Barga et al. 2017).

Table 2. Seed yield and quality of limestone hawksbeard seed 

lots collected in the Intermountain region, cleaned by the 

Bend Seed Extractory, and tested by the Oregon State Seed 

Laboratory or the USFS National Seed Laboratory (USFS BSE 

2017).

Seed lot 

characteristic

Mean Range Samples 

(no.)

Bulk weight (lbs) 1.17 0.28-4.5 6

Clean weight 

(lbs)

0.14 0.006-0.56 6

Clean-out ratio 0.097 0.02-0.15 6

Purity (%) 97.3 95-99 6

Fill (%)1 85.5 75-97 6

Viability (%)2 85 70-97 5

Seeds/lb 120,039 96,508-144,366 6

Pure live seeds/

lb

95,097 80,680-110,110 5

1 100 seed X-ray test

2 Tetrazolium chloride test

Marketing Standards. Acceptable seed purity, 

viability, and germination specifications vary with 

revegetation plans. Purity needs are highest for 

precision seeding equipment used in nurseries, 

while some rangeland seeding equipment handles 

less clean seed quite well.

Viability of wild-collected limestone hawksbeard 

seed can be highly variable (Shock et al. 2011; 

Barga et al. 2017). For tapertip hawksbeard, 

Walker and Shaw (2005) recommended 80 to 90% 

viability and 90% purity as marketing standards.

AGRICULTURAL SEED 

PRODUCTION

There are several challenges to agricultural 

production of limestone hawksbeard seed. At the 

Aberdeen PMC, field establishment was difficult, 
Crepis intermedia A. Gray. 9

plants took several years to produce seed, seed 

was prone to insect damage, and because of 

indeterminate seed ripening, multiple harvests 

were needed to maximize seed yields (St. John 

and Tilley 2012). In seed production plots grown 

at Oregon State University’s Malheur Experiment 

Station (OSU MES) near Ontario, Oregon (Fig. 

10), limestone hawksbeard began producing 

seed in its third year. Seed yield averaged 100 to 

350 lbs/acre (112-392 kg/ha) for 3 years, before 

production plots were tilled under, meaning stands 

may have been capable of producing seed beyond 

3 years. Seed was harvested multiple times using 

a leaf blower in vacuum mode in the first harvest 

year and in single mechanical harvest in the next 2 

years (Shock et al. 2018).

Figure 10. Limestone hawksbeard production plots growing 

at Oregon State University’s Malheur Experiment Station near 

Ontario, OR. Photo: N. Shaw, USFS.

Agricultural Seed Certification. It is essential to 

maintain and track the genetic identity and purity 

of native seed produced in seed fields. Tracking 

is done through seed certification processes 

and procedures. State seed certification offices 

administer the Pre-Variety Germplasm (PVG) 

Program for native field certification for native 

plants, which tracks geographic source, genetic 

purity, and isolation from field production through 

seed cleaning, testing, and labeling for commercial 

sales (Young et al. 2003; UCIA 2015). Growers 

should plant certified seed (see Wildland Seed 

Certification section) and apply for certification 

of their production fields prior to planting. The 

systematic and sequential tracking through 

the certification process requires pre-planning, 

understanding state regulations and deadlines, 

and is most smoothly navigated by working 

closely with state certification agency personnel.

Site Preparation and Seed Treatments. At OSU 

MES, emergence of limestone hawksbeard was 

improved when seeds were covered with sawdust 

mulch and row cover (Shock et al. 2011). Seeded 

areas were weed-free, silt loam soils with pH of 

8.3 and 1.1% organic matter (Shock et al. 2018). 

Soil crusting and bird damage were causes of 

poor stand emergence in earlier fall seedings 

of forbs at OSU MES, but researchers observed 

natural emergence of seed from established 

perennials when fallen seed was covered by thick 

layers of organic debris (Shock et al. 2011). They 

began tests of various seed protection measures, 

including row cover (N-sulate, DeWitt Co, Sikeston, 

MO) to protect against soil desiccation and bird 

damage; sawdust (0.26 oz/foot [18.7 g/m] of row) 

to mimic the protection of organic debris; sand 

(same application rate as sawdust, and applied 

on top of sawdust where both were used) to hold 

seed in place; and fungicide seed pre-treatment 

(3.5 oz [100 g] each of Metalaxyl [Ridomil] and 

Captan in 2 pints [1 L] of water) to protect from 

damping off. Row cover and sawdust improved 

emergence of limestone hawksbeard most, and 

fungicide did not appear necessary. Seeding 

occurred on November 12, 2009. Plots were drip 

irrigated for 24 hours on November 20, 2009, and 

emergence results evaluated on March 10, 2010. 

Results are provided in Table 3 (Shock et al. 2011).

Table 3. Emergence of limestone hawksbeard 4 months after 

fall seeding with various combinations of seed protection 

treatments (Shock et al. 2011). 

Row 

cover

Sawdust Sand Fungicide 

seed trt

Emergence 

(%)*

Yes Yes Yes Yes 76.6a

Yes Yes No Yes 64.5b

Yes Yes No No 86.2a

Yes No No Yes 57.6b

No Yes No Yes 38.6c

*Emergence percentages followed by different letters are 

significantly different (P < 0.05).

Weed Management. Weed management is 

important to successful establishment. Hand 

removal, pre-emergent herbicide, and physical 

barriers have been used to control weeds in 

limestone hawksbeard production plots. At 

Fountain Green Experimental Farm (FGEF) in Utah, 

limestone hawksbeard emergence following 

November seeding was poor because of weed 

competition, and stands were tilled under in July 

of the next year (Vernon et al. 2007).

At OSU MES, limestone hawksbeard stands were 

hand weeded for the majority of their 7 years 

of growth, except for one year when the preemergent, pendimethalin, was broadcast at 2 

pints/acre (2.3 L/ha) to control weed emergence 
10 Crepis intermedia A. Gray

in established stands. Success of the weed 

treatments was not reported (Shock et al. 2018).

Various weed barriers were evaluated on 

production plots in Utah. Limestone hawksbeard 

plugs grown in the greenhouse over the 2005-06 

winter were planted into holes in the weed barrier 

in May 2006. Despite difficulties with installation 

and maintenance of the barriers, which included 

flooding and high winds, plants produced leaves 

in the first season. Survival to the following 

spring was 28% in plots without weed barrier, 

13% with a plastic barrier, and about 50% with 

a woven lumite weed barrier fabric. Survival was 

significantly better (P < 0.05) with fabric than with 

plastic, but not significantly different than with no 

barrier. Weed barriers reduced the amount of hand 

weeding, which was extensive in the no barrier 

plots (Meyer and Vernon 2008).

Pests. Limestone hawksbeard is a host for several 

fungal species (Farr and Rossman 2017), and in 

common gardens in Ephraim and Fountain Green, 

Utah, newly emerging stands were decimated 

by flea beetles and there was no survival to next 

season (Jones and Whittaker 2009). Although 

a documented host for Puccinia crepidisacuminatae, P. crepidis-montanae, P. dioicae, P. 

hieraciata, and P. hieracii (Garrett 1914; Farr and 

Rossman 2017), the extent that these organisms 

reduce seed production has not been reported.

Seeding. Fall seeding was used to establish 

limestone hawksbeard seed production plots at 

OSU MES and at FGEF. At OSU MES, limestone 

hawksbeard was seeded in late November with a 

small-plot grain drill. Seed was deposited on the 

soil surface at 20 to 30 seeds/foot (66-98 seed/m) 

of row, and rows were spaced 30 inches (76 cm) 

apart. A narrow band of sawdust was applied over 

the seed at 0.26 oz/foot (18.7 g/m) of row, and the 

plots were covered with N-sulate row cover (Shock 

et al. 2018). At FGEF, limestone hawksbeard was 

direct seeded in November using a precision 

planter. Seeding in spring was a complete failure 

(Vernon et al. 2007).

Establishment and Growth. Predation on 

seedlings and seed heads can limit establishment, 

growth, and seed yield. At OSU MES, row cover 

was used to protect seedlings from birds until 

March, when it was replaced with bird netting. 

As seedlings emerged, bird seed was provided 

away from the production plot as a way to 

reduce predation by California quail (Callipepla 

californica). For growth maintenance, limestone 

hawksbeard stands were fertilized (50 lb N, 10 lb 

P, and 0.3 lb Fe/acre [56 kg N, 11 kg P, 0.3 kg Fe/

ha]) in their second year though 12-inch (30 cm) 

deep drip tape. Iron (0.3 lb Fe/acre [0.3 kg/ha]) was 

applied again in the third and last production year 

(Shock et al. 2018).

Greenhouse grown plants were used to establish 

production fields at Ephraim, Utah. Limestone 

hawksbeard plants were more robust with better 

survival and more early flowers than tapertip 

hawksbeard plants planted at the same time. 

Some limestone hawksbeard plants flowered 

within two years of planting (Vernon et al. 2007), 

and most were flowering by their third year. Aphids 

and other seed head predators reduced seed 

production (Meyer and Vernon 2008).

Irrigation. Added irrigation significantly increased 

limestone hawsbeard seed production in 2 of 4 

years at OSU MES (Table 6; Shock et al. 2018). 

Irrigation trials began in March 2013 in plots 

seeded in late November 2011. Treatments of 

0, 4, or 8 inches (101 or 203 mm) of water were 

delivered at about 2-week intervals beginning 

at the time of bud formation and flowering (see 

Table 4) through drip tape buried 12 inches (30 

cm) deep. In 2015, the year with the highest 

number of growing degree days, seed yield was 

significantly increased to 176.6 lb/acre (198 kg/ha) 

with 8 inches (203 mm) of water applied (Tables 

5 and 6). In 2018, a year with below average 

spring precipitation, seed yield was significantly 

increased to 151.0 lbs/acre (169 kg/ha) with 4 

inches (101 mm) of water applied (P = 0.1) (Tables 

5 and 6; Shock et al. 2018).

Seed Harvesting. At OSU MES, limestone 

hawksbeard flowered and produced seed the third 

year after fall planting. Seed was harvested weekly 

using a leaf blower in vacuum mode in the first 

production year (2015). In 2016, three years after 

irrigation trials were started, flowering duration 

was shorter and more uniform. This made it 

possible to harvest once by mowing and bagging 

plants just before seed heads opened. Single 

annual mechanical harvest yields were similar to 

that of multiple hand harvests in 2015 (Table 6). 

Immature (light yellow) and mature (brown) seed 

from the machine harvest in 2016 was analyzed 

for viability (TZ). Of the 2016 harvest, 23% of seed 

was immature, and viability tested indicated that 

5% of immature seed was viable. The rest of the 

harvest (77%) was mature, and 57% of mature 

seed was viable (Shock et al. 2018).
Crepis intermedia A. Gray. 11

Table 4. Timing of flowering and seed harvest dates in 2015 

to 2018 for seed production fields growing over 4 years at 

Oregon State University’s Malheur Experiment Station in 

Ontario, OR (Shock et al. 2018). Seed yields are provided in 

Table 6.

Year Start of 

flowering

End of flowering Harvest date(s)

2015 Apr 28 June 1 (peak 

flowering May 5)

Weekly June 

1-July 2

2016 Apr 29 May 25 May 26

2017 May 5 June 7 June 8

2018 May 5 May 25 May 31

Table 5. Precipitation (in) and growing degree days (°F) 

in 2015 to 2018 at Oregon State University’s Malheur 

Experiment Station in Ontario, OR (Shock et al. 2018).

Year Spring Winter + 

Spring

Fall + 

Winter + 

Spring

Growing degree 

hrs (50-86 °F) 

Jan-June

2015 3.2 5.9 10.4 1610

2016 2.2 5.0 10.1 1458

2017 4.0 9.7 12.7 1196

2018 1.9 4.9 5.8 1342

5-yr ave 2.4 5.6 9.3 1207 

(25-yr ave)

Seed Yields and Stand Life. Limestone 

hawksbeard first produced seed in the third year 

after seeding (Shock et al. 2018). Seed yields 

ranged from 55.5 to 301.5 lbs/acre (62-338 kg/

ha) (Table 6). Stands produced harvestable seed 

for at least 4 years, but seed yield can be variable 

(Shock et al. 2018).

Table 6. Seed yield (lbs/acre) for showy goldeneye stands 

with and without growing season irrigation at Oregon State 

University’s Malheur Experiment Station in Ontario, OR (Shock 

et al. 2018).

Year* 0 in 4 in 8 in

----------lbs/acre--------

2015** 68.6a 55.5a 166.3b

2016 83.6 87.0 77.8

2017 301.5 268.1 287.1

2018 98.3a 151.0b 100.2a

Ave 138.0 140.4 155.5

*Seed was hand harvested (blower in vacuum mode) weekly 

in 2015 and was machine harvested once before seed heads 

opened in 2016-2018. 

**Values within a row followed by different letters are 

significantly different (P ≤ 0.1).

NURSERY PRACTICE

Although plugs were used to establish seed 

production stands and for revegetation studies, 

guidelines for nursery production were not 

reported. However, researchers at the Aberdeen 

PMC suggest the procedures used to grow 

tapertip hawksbeard would apply to limestone 

hawksbeard. They planted stratified seed 0.2 to 

0.5 inch (0.6-1.3 cm) deep in potting soil in the 

greenhouse. They noted that the long delicate 

taproot produced was easily damaging during 

transplanting (St. John and Tilley 2012).

WILDLAND SEEDING AND 

PLANTING 

Outcomes of seeding limestone hawksbeard for 

revegetation were not reported in the literature, 

but some guidance on seeding rates, depths, 

timing and locations has been proposed based on 

seed size and experience gained in establishment 

of seed production plots. Based on the weight 

of limestone hawksbeard seed, the full seeding 

rate recommended for 25 seeds/ft2 (269/m2) 

is 13 PLS/acre (14.6 kg/ha) (St. John and Tilley 

2012). This rate would be adjusted according to 

its desired proportion in a seed mix, which Ogle 

et al. (2012) recommended should be less than 

10% for hawksbeard species. Seeding in fall in 

fine sandy loam to silty soils at a depth of 0.13 to 

0.25 inch (0.3-0.6 cm) is recommended. Grazing 

should be deferred for at least 2 growing seasons 

in revegetated areas (Ogle et al. 2012; St. John 

and Tilley 2012). Vigor of hawksbeard seedlings is 

generally low, but plants are long lived (Ogle et al. 

2012).

Use of plugs in a revegetation study was 

somewhat successful in an exclosure in Wells, 

Nevada, where limestone hawksbeard survival was 

38% one year after planting (Meyer and Vernon 

2008).

ACKNOWLEDGEMENTS 

Funding for Western Forbs: Biology, Ecology, and 

Use in Restoration was provided by the USDI BLM 

Great Basin Native Plant Materials Ecoregional 

Program through the Great Basin Fire Science 

Exchange. Great thanks to the chapter reviewers: 

Shaun Bushman, USDA, Agricultural Research 

Service and Scott Jensen, USDA FS Rocky 

Mountain Research Station.
12 Crepis intermedia A. Gray

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apomicts of the North American Crepis agamic complex 

(Asteraceae). Botany. 86: 877-885.

Wright, R.D.; Mooney, H.A. 1965. Substrate-oriented distribution 

of bristlecone pine in the White Mountains of California. The 

American Midland Naturalist. 73(2): 257-284.

Young, J.A.; Young, C.G. 1986. Collecting, processing and 

germinating seeds of wildland plants. Portland, OR: Timber 

Press. 236 p.

Young, S.A.; Schrumpf, B.; Amberson, E. 2003. The Association 

of Official Seed Certifying Agencies (AOSCA) native plant 

connection. Moline, IL: AOSCA. 9 p.

RESOURCES

AOSCA NATIVE PLANT CONNECTION

https://www.aosca.org/wp-content/uploads/

Documents///AOSCANativePlantConnectionBrochure_

AddressUpdated_27Mar2017.pdf

BLM SEED COLLECTION MANUAL

https://www.blm.gov/sites/blm.gov/files/programs_naturalresources_native-plant-communities_native-seed-development_

collection_Technical%20Protocol.pdf

ENSCONET SEED COLLECTING MANUAL

https://www.publicgardens.org/resources/ensconet-seedcollecting-manual-wild-species

HOW TO BE A SEED CONNOISSEUR

http://www.utahcrop.org/wp-content/uploads/2015/08/How-tobe-a-seed-connoisseur20May2015.pdf

OMERNIK LEVEL III ECOREGIONS

https://www.epa.gov/eco-research/ecoregions

CLIMATE SMART RESTORATION TOOL

https://climaterestorationtool.org/csrt/

SEED ZONE MAPPER

https://www.fs.fed.us/wwetac/threat-map/

TRMSeedZoneMapper.php

AUTHORS

Corey L. Gucker, Great Basin Fire Science Exchange Support

University of Nevada, Reno

Boise, ID | cgucker@unr.edu 

Nancy L. Shaw, Research Botanist (Emeritus)

USDA Forest Service, Rocky Mountain Research Station

Boise, ID | nancy.shaw@usda.gov 

Gucker, Corey L.; Shaw Nancy L. 2019. Limestone hawksbeard 

(Crepis intermedia A. Gray). In: Gucker, C.L. ; Shaw, N.L., eds.

Western forbs: Biology, ecology, and use in restoration. Reno,

NV: Great Basin Fire Science Exchange. 14 p. Online:

http://greatbasinfirescience.org/western-forbs-restoration

COLLABORATORS