Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-1

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Acaena novaezelandica biddy-biddy Open, disturbed, well-drained sites, including stable dunes, open scrub, grassy areas, and trampled sites in 

coastal habitats where some summer moisture is available and frosts are infrequent. Plants thrive on poor soils and compete poorly with established vegetation. 

perennial shrub, subshrub 

Acroptilon repens Russian knapweed Prefers heavy, often saline soils of bottomlands and subirrigated slopes and plains. Commonly found along 

roadsides, riverbanks, irrigation ditches, pastures, waste places, clearcuts, croplands, and hayfields. Prefers similar sites to those occupied by basin wildrye (Elymus 

cinereus). Does not readily establish in healthy native vegetation, requires disturbance. 

perennial forb/herb 

Alopecurus myosuroides 

blackgrass Blackgrass prefers moist soils. It grows most abundantly 

in the low areas of fields and on heavy soils with a high winter water table, but is not confined to these areas. 

annual grass 

Ammophila arenaria 

European beachgrass Found along the west coast of the United States, it 

thrives in areas of active sand movement and most often occupies the windward slopes of exposed dunes. However, it may extend inland for several miles. It grows on well-drained soils with various mineral compositions, including the sands of the Pacific Coast. 

perennial grass 

Anchusa arvensis small bugloss Annual bugloss grows along roadsides, in disturbed 

habitats, pastures, and cultivated fields. 

annual forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-2

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Anchusa officianalis 

common bugloss Often found in waste places and roadsides. bienneial 

perennial 

forb/herb 

Artemisia absinthium 

absinth wormwood Frequently found near streams, lakes or irrigation 

ditches. 

perennial shrub/ subshrub

forb/herb 

Arctium minus lesser burrdock Commonly found growing along roadsides, ditchbanks, 

in pastures and waste areas. 

biennial forb/herb 

Brassica rapa field mustard Found in cultivated fields, roadsides and waste areas. annual biennial forb/herb Bromus rigidus ripgut brome Common in waste areas, roadsides and railroads. Is also 

invasive on rangelands. 

annual grass 

Brachypodium sylvaticum 

slender false brome Closed-canopy coniferous forests, riparian forests, forest 

edges, and upland prairies in full sun. Can become 

dominant in the understory of forests that it invades, forming nearly monospecific stands that appear to outcompete and completely exclude native forbs and grasses. Tom Kaye (Institute of Applied Ecology) reports that B. sylvaticum can competitively exclude 

other species (including endangered plants and butterfly species that depend on them) in the understory of coniferous forests it invades, and that it even inhibits establishment of tree seedlings by sequestering muchneeded soil moisture. 

perennial grass 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-3

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Bromus tectorum cheatgrass Although cheatgrass can be found in both disturbed and 

undisturbed shrub-steppe and intermountain grasslands (e.g., where dominant grasses are bluebunch wheatgrass [Pseudoroegneria spicata] and Idaho fescue [Festuca idahoenesis]), the largest infestations are usually found in disturbed shrub-steppe areas, overgrazed rangeland, abandoned fields, eroded areas, sand dunes, roads, and waste places. 

annual grass 

Buddleja 'davidii orange eye 

butterflybush 

Prefers well drained, average soil. Once established, can thrive in fairly dry condition. 

perennial shrub 

Carduus acanthoides 

spiny plumeless thistle 

Infrequently to locally abundant in pastures, stream valleys, fields and roadsides. 

biennial forb/herb 

Cardaria draba whitetop Variety of non-shaded, disturbed conditions, including 

roadsides, waste places, fields, gardens, feedlots, watercourses, open grasslands, and along irrigation ditches. Found in variety of soil types, even in saline soils, except not found in acidic soils. Most aggressive, rapid expansion occurs in irrigated conditions or during moist years. 

perennial forb/herb 

Carduus nutans musk thistle Musk thistle thrives in disturbed areas, such as 

roadsides, grazed pastures, burned areas, and old fields, but also can invade deferred pastures and native grasslands. It can occur in almost all habitats except dense forests, high mountains, deserts, and frequently cultivated farmlands. 

biennial perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-4

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Cardaria pubescens hairy whitetop Well adapted to moist habitats, especially sub-irrigated 

pastures, rangeland, roadsides, and ditch banks. 

perennial forb/herb 

Carduus pycnocephalus 

Italian plumeless thistle 

Invades pasture, range and forest lands along with roadsides, waste areas, ditch banks, stream banks and grain fields. 

annual forb/herb 

Carduus tenuiflorus 

winged plumeless thistle 

Infests roadsides and waste areas, and can be a major problem on hill pastureland. 

annual forb/herb 

Centaurea biebersteinii 

spotted knapweed Best adapted to well-drained, light-textured soils in 

areas that receive some summer rainfall. This includes ponderosa pine (Pinus ponderosa) and Douglas-fir 

(Pseudotsuga menziesii) forests and shrub-steppe 

habitats with bluebunch wheatgrass, needle-and-thread, and Idaho fescue. Infestations may change soil conditions to the advantage of this species (see 3.1.2) 

biennial perennial 

Centaurea cyanus garden cornflower No description. annual forb/herb Centaurea debeauxii (C. pratensis) 

meadow knapweed Best adapted to well-drained, light-textured soils in 

areas that receive some summer rainfall. This includes 

ponderosa pine and Douglas-fir forests and shrub-steppe habitats with bluebunch wheatgrass, needle-and-thread, 

and Idaho Fescue.

perennial forb/herb 

Centaurea diffusa diffuse knapweed Disturbed or overgrazed lands are prime habitat, but can 

also invade undisturbed grasslands, shrublands, riparian communities, forested benchlands, and rugged terrain. 

biennial perennial forb/herb 

Centaurea jacea brownray knapweed Infests roadsides, waste areas, fields and pastures. perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-5

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Centaurea melitensis 

Maltese star-thistle Grows on various soil types; usually introduced on 

roadsides and waste areas. 

annual biennial forb/herb 

Centaurea solstitialis 

yellow starthistle Best adapted to open grasslands with deep well-drained 

soils and average annual precipitation of 10 to 60 inches. 

annual forb/herb 

Centaurea triumfettii 

squarrose knapweed Invades juniper-Idaho fescue and big sagebrushbunchgrass rangelands, and dry rocky sites of degraded 

juniper-shrub savanna with scattered western juniper 

and ponderosa pine. 

perennial forb/herb 

Chondrilla juncea rush skeletonweed Sandy to gravelly, well-drained soils or shallow soils. 

Seedlings require moisture for up to 6 weeks to develop a persistent root system. 

perennial forb/herb 

Cirsium arvense Canada thistle Prefers and is invasive in prairies and other grasslands 

and riparian areas with deep, well-aerated, mesic soils, but also occurs in almost every upland herbacious community, especially roadsides, abandoned fields, and pastures. 

perennial forb/herb 

Cichorium intybus chicory Widespread along roadsides and disturbed sites. biennial perennial forb/herb Cirsium ochrocentrum 

yellow spine thistle Can be found in dry sandy and gravelly soil in prairies, 

pastures and open disturbed sites. 

biennial perennial forb/herb 

Cirsium undulatum wavyleaf thistle Found in foothills, meadows and rangeland. biennial perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-6

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Cirsium vulgare bull thistle Occurs in dry to moist habitat, fields, pastures, 

grasslands, roadways, forest clearings, rock outcrops, and along waterways. Does best in areas with moderate slope. It is not shade tolerant. 

biennial forb/herb 

Clematis vitalba evergreen clematis Found in forest lands and in the margins and openings 

of forested lands. It is also found in riparian areas established with willows, in waste areas, and in coastal and lowland areas (Cronk and Fuller 1995). 

perennial vine, subshrub 

Convolvulus arvensis 

field bindweed Cultivated fields, orchards, vineyards, gardens, pastures, 

abandoned fields, roadsides, waste places. Grows best on moist fertile soils. Tolerates poor, dry, gravelly soils, but seldom grows in wet soils. Inhabits regions with temperate, Mediterranean, and tropical climates. 

perennial vine, forb/herb 

Conium maculatum 

poison hemlock Tolerates poorly drained soils and frequents stream and 

ditch banks. Commonly occurs along roadsides, field margins, ditches, and in low-lying waste places. Can invade native riparian woodlands and open floodplains along waterways. 

biennial forb/herb 

Cortaderia spp. pampas grass Highly competitive with native plants once seedlings 

become established and is a substantial threat to the ecological quality of preserves, particularly in coastal and grassland sites. Particularly threatened habitats include coastal sand dunes and inland sand hills. 

perennial grass 

Crupina vulgaris common crupina Primary habitat is southern slopes in steep canyon 

grasslands, waste areas, arid hillsides, rangelands, and grassy slopes. 

annual forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-7

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Cyperus esculentus yellow nutsedge Prefers moist, sandy soils. perennial sedge Cynoglossum officinale 

houndstongue Well-adapted to forested areas, roadsides, meadows, 

pastures, and waste places, often found on gravelly, somewhat alkaline soils. 

biennial forb/herb 

Cytisus scoparius Scot's broom Found in pastures, forest, and wastelands. This nitrogen 

fixer which has prolific and vigorous growth patterns may have the ability to alter native plant succession. 

perennial shrub 

Cytisus striatus striated broom Found in open disturbed sites, such as logged or burned 

sites, roadsides, and pastures, and can invade +/- undisturbed grasslands, coastal scrub, oak woodlands, and open forests. Does not tolerate heavy shade, but can tolerate minimal shade along the edges of forest canopies. Drought-resistant. 

perennial shrub 

Daucus carota wild carrot Found in pastures, meadows, dry areas and rocky soils. biennial forb/herb Dactylis glomerata orchardgrass Found along roadsides and in disturbed habitats. perennial grass Dipsacus fullonum Fuller's teasel Found in moist sites, especially along irrigation ditches, 

canals and disturbed sites. 

biennial forb/herb 

Dipsacus laciniatus cutleaf teasel Grows in open, sunny habitats that range from wet to 

dry levels. Optimal conditions seem to be mesic habitats. Roadsides and heavily disturbed areas are the most common habitats of teasel. Teasel sometimes occurs in high quality prairies, savannas, seeps, and sedge meadows. 

biennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-8

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Digitalis purpurea purple foxglove Found in logged areas, along roadsides and in coastal 

pastures. 

biennial forb/herb 

Echium vulgare blueweed/vipers 

bugloss 

Found in waste ground, roadsides, gravel bars, and sand bars. 

biennial perennial forb/herb 

Elymus repens quackgrass Tolerates a variety of soil types, including saline 

conditions, but grows most vigorously in soils of pH 6.5-8.0. Will dominate fields for several years after abandonment, but will not tolerate shade. In western North America, quackgrass invades wet meadows, wetland borders and other low-lying wet areas of grasslands and prairies. 

perennial grass 

Euphorbia esula leafy spurge Occurs in untilled, non-cropland habitats, including both 

disturbed and undisturbed sites, especially abandoned cropland, pastures, rangelands, woodlands, roadsides, and waste places. Tolerant of a wide range of soils from rich, moist soils of riparian zones to nutrient-poor, dry soils of western rangelands. It is most aggressive in semi-arid situations where competition from associated species is less intense, so invades most rapidly on dry hillsides, dry prairies, or rangelands. 

perennial forb/herb 

Foeniculum vulgare 

sweet fennel Found along waste places, roadsides, riverbanks, and 

other nonagricultural situations (Parsons 1973) 

biennial perennial forb/herb 

Genista monspessulana 

French broom See Scot's broom (Cytisus scoparius). perennial shrub 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-9

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Geranium robertianum 

stinky bob Highly adaptable. It is found in moist forests with 

varying amounts of canopy closure (i.e., from closed canopy to forest gaps to more open canopies), and on dry rocky outcrops. 

annual biennial forb/herb 

Gypsophila paniculata 

babysbreath Found in pastures, open areas and rangeland. perennial forb/herb 

Hedera helix English ivy Grows easily in many types of soil and in sun or shade. 

English ivy is fairly drought tolerant once it is established. 

perennial vine/subshrub 

Heracleum mantegazzianum 

giant hogweed Thrives in many habitats but does particularly well 

where the soil has been disturbed, such as on wasteground or on riverbanks, where erosion combined with a good supply of groundwater provide ideal conditions. 

perennial forb/herb 

Hieracium aurantiacum 

orange hawkweed Elevational range of 2000 to 5500 ft. in abandoned 

farmlands, pastures, lawns, fields, roadsides, mountain meadows, and forest clearings. They do not tolerate full shade, so they are not found in densely forested areas, but can dominate forest openings and margins. Prefer well-drained, coarse-textured soils moderately low in organic matter. 

perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-10

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Hieracium caespitosum 

meadow hawkweed Elevational range of 2000 to 5500 ft. in abandoned 

farmlands, pastures, lawns, fields, roadsides, mountain meadows, and forest clearings. They do not tolerate full shade, so they are not found in densely forested areas, but can dominate forest openings and margins. Prefer well-drained, coarse-textured soils moderately low in organic matter. 

perennial forb/herb 

Hieracium laevigatum 

Smooth hawkweed Area of highest concentration is in Whatcom County, 

Washington, where it is most common along road shoulders. However, plants are starting to invade fields and other areas adjacent to roadside infestations. 

perennial forb/herb 

Hyoscyamus niger black henbane Disturbed open sites, roadsides, fields, waste places, and 

abandoned gardens. Grows best in sandy or welldrained loam soils with moderate fertility. Does not tolerate waterlogged soils. 

annual biennial forb/herb 

Hypericum perforatum 

common St. Johnswort 

Rangeland and pastures (especially when poorly managed), fields, roadsides, forest clearings in temperate regions with cool, moist winters and dry summers. Grows best in open, disturbed sites and on slightly acidic to neutral soils. Does not tolerate saturated soils. 

perennial forb/herb 

Hypochaeris radicata 

hairy catsear Found in disturbed sites, waste areas, lawns, gardens, 

pastures and cultivated fields. 

perennial forb/herb 

Ilex aquifolium English holly Grows in forests, parks, gardens and in plains and 

mountain areas 

perennial tree/shrub 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-11

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Isatis tinctoria dyer's woad Disturbed and undisturbed sites, roadsides, railroad 

rights-of-ways, fields, pastures, grain and alfalfa fields, forest and rangeland. Often grows on dry, rocky or sandy soils. 

biennial perennial forb/herb 

Kochia scoparia kochia Commonly found in cultivated fields, gardens, 

roadsides, ditchbanks and waste areas. 

annual forb/herb 

Lathyrus latifolius perennial pea No description perennial vine/subshrub/f

rb/herb 

Lactuca serriola prickly lettuce A weed in orchards, ornamental stock, horticultural and 

agronomic crops, most irrigated crops, and roadsides. 

annual biennial forb/herb 

Lepidium latifolium 

broadleaved pepperweed 

Thrives in nutrient-rich soils. perennial forb/herb 

Leucanthemum vulgare 

oxeye daisy Fields, pastures, waste places, roadsides, railroads, 

prairies, slopes, disturbed sites. 

perennial forb/herb 

Linaria dalmatica Dalmatian toadflax Rapidly colonizes open or disturbed areas, especially 

roadsides, fences, rangelands, croplands, clearcuts, and pastures. Seedlings are ineffective competitors for soil moisture against established perennials and winter annuals, but, once established, both species of toadflax suppress other vegetation mainly by intense competition for limited soil water. Mature plants are particularly competitive with winter annuals and shallow-rooted perennials. Dalmatian toadflax prefers sandy or gravelly soil. It is most commonly found along roadsides, rangelands, dry forests and pastures but can adapt to fit a wide range of habitats. 

perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-12

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Ligustrum vulgare European privet Prefers fine and medium textured soils. perennial shrub Linaria vulgaris butter and eggs Found along roadsides, waste places, and cultivated 

fields. 

perennial forb/herb 

Lotus corniculatus birdfoot deervetch Found in fields, roadsides, and disturbed areas along 

railroads. 

perennial forb/herb 

Lotus pedunculatus big trefoil Big trefoil can grow in standing water, high acid soils, 

or soils with a high aluminum content. It does well in soils with low fertility. 

perennial forb/herb 

Lythrum salicaria purple loosestrife Grows in aquatic areas, including wetlands, bogs, along 

stream and river banks, lake shores, in ditches and disturbed wet soil areas. 

perennial forb/herb 

Marrubium vulgare horehound Widely distributed along roadsides, dry waste areas and 

in gardens. 

perennial forb/herb 

Melilotus officinalis, M. alba 

yellow sweetclover, white sweetclover 

Common along roadsides and waste areas (often first plants to appear on disturbed sites) and is sometimes promoted for soil stabilization and improvement. 

annual biennial perennial 

forb/herb 

Onopordum acanthium 

Scotch cottonthistle Invades most habitats, from dry to moist sites. Occurs in 

waste places, along roadsides, in dry meadows, rangelands, pastures, and sometimes waterways. 

biennial forb/herb 

Phalaris arundinacea 

reed canarygrass Found in wet areas along streams and in marshes. perennial grass 

Plantago lanceolata 

narrowleaf plantain Found along roadsides, pastures and other disturbed 

sites such as lawns and gardens. 

biennial perennial forb/herb 

Polygonum cuspidatum 

Japanese knotweed Found along roadsides, waste areas, ditchbanks, 

wetlands, streambanks and hillsides. 

perennial subshrub, shrub

forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-13

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Polygonum polystachyum 

Himalayan knotweed Grows in wet meadows and marshes of forested areas 

between 2500-4000 m (8200-13000 ft) elevation in its native range, but can be found to sea level in the Pacific Northwest. 

perennial forb/herb 

Potentilla recta sulphur cinquefoil Found in open grasslands, shrubby areas, open forests, 

logged areas, roadsides, waste places, and abandoned fields. Sulfur cinquefoil is an early successional species that colonizes disturbed sites, as well as forest edges. It cannot survive shade, such as full forest canopy. Sulfur cinquefoil is becoming co-dominant with spotted knapweed on many sites and now is apparently replacing knapweed in some areas of western Montana. 

perennial forb/herb 

Polygonum sachalinense 

giant knotweed Giant knotweed shares habitat with Japanese knotweed. 

Both species are found along stream banks, in moist waste places, neglected gardens, roadsides, and railroad right-of-ways. In Washington it is more commonly found west of the Cascade Mountains. 

perennial forb/herb 

Ranunculus repens creeping buttercup Most often found in lowland pastures and wet areas. perennial forb/herb Rubus discolor Himalayan blackberry Grows along roadsides, creek gullies, river flats, fence 

lines (Parsons and Amor 1968), and right-of-way corridors. R. discolor tends to prefer wet sites (Amor and Stevens 1976), but can also be found on dry roadsides in western parts of the region. 

perennial shrub 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-14

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Rubus laciniatus cutleaf blackberry Found in disturbed upland sites. It may often be found 

growing along fence rows, roadsides, railroad grades, and in disturbed pastures. 

perennial Vine/ shrub/ 

subshrub 

Salvia aethiopis Mediterranean sage Invades pastures, meadows, rangeland and other open 

areas. 

biennial forb/herb 

Salsola kali Russian thistle Well-adapted in cultivated dryland agriculture, but is 

also found on disturbed wasteland, over-grazed rangeland, and irrigated cropland. 

annual forb/herb 

Saponaria officinalis 

bouncingbet Grows in moist ditches, waste places, near old 

homesites, along roadsides, and as a planted ornamental in some areas of the country. 

perennial forb/herb 

Sasa palmata broadleaf bamboo No description. perennial shrub, forb/herb Salsola tragus prickly Russian thistle Found in disturbed sites, rocky slopes, and flats, 

frequently occurring on clay soils. 

annual forb/herb 

Secale cereal cereal rye Found along established roadsides, waste places and 

open rangeland. 

annual biennial grass 

Senecio jacobaea tansy ragwort Invades cut-over forest lands, irrigated and non-irrigated 

pastures, woodland pastures, and fallow lands. Although it prefers light, well-drained soils in cool, moist climates and rarely is tolerant of high water tables or acidic soils, it can grow in most soil moisture regimes, even where there are hot, dry summers. It can over-winter in areas where temperatures reach -20°F or lower if there is good snow cover. 

perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-15

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Sonchus arvensis field sowthistle Adapted to many soil types and moisture regimes, seems 

to prefer low, fine-textured soils, like loams, and does better under alkaline or neutral conditions. 

perennial forb/herb 

Solanum dulcamara 

climbing nightshade Typically found growing in moist waste areas, fence 

rows, drainage ditches and waterways, and may form large colonies or thickets. Also becomes established in orchards, vineyards and residential landscapes. 

perennial subshrub, 

forb/herb 

Solanum elaeagnifolium 

silverleaf nightshade Found in disturbed sites such as fallow fields, gardens, 

and vacant areas, especially those with sandy soil. 

perennial forb/herb 

Taeniatherum caput-medusae 

medusahead Areas most susceptible to invasion by medusahead are 

soils with high clay content, well-developed profiles, and those receiving run-off from infested areas (The Nature Conservancy 1988). Medusahead is displacing cheat grass on more mesic sites. 

annual grass 

Tanacetum parthenium 

feverfew Found in mountain scrub, rocky slopes, walls, waste 

places and gardens, but avoids acid soils. 

perennial forb/herb 

Tanacetum vulgare common tansy Prefers full sun and well-drained but moist soils and is 

prevalent along ditches, creeks, and roadways. Commonly occurs in disturbed areas at low elevations. 

perennial forb/herb 

Tribulus terrestris puncturevine Grows on disturbed sites where it needs relatively high 

temperatures for germination and growth. Adapted to a wide range of soil conditions. 

perennial forb/herb 
Preventing and Managing Invasive Plants Final Environmental Impact Statement 

Appendix B-16

APPENDIX B Current Invasive Plant Species on National Forest the Pacific Northwest Region 

SCIENTFIC 

NAME 

COMMON 

NAME HABITAT PREFERENCE LIFE CYCLE HABIT 

Ulex europaeus common gorse Found along coastal areas of Oregon and Washington, 

often in upper elevation pasture land. 

perennial shrub 

Urtica dioica stinging nettle Grows in shaded moist areas along streams, or in deep, 

rich, undisturbed soils. Difficult to distinguish from the native species of Urtica. 

perennial forb/herb 

Ventenata dubia North Africa grass Occurs in grain crops, rangeland and disturbed sites. perennial grass Verbascum thapsus common mullein Natural meadows and forest openings, where it adapts 

easily to a wide variety of site conditions. Prefers, but is not limited to, dry sandy soils. It is shade intolerant. Primarily a weed of pastures, hay fields, roadsides, rights-of-way, and abandoned areas. 

biennial forb/herb 

Vinca major bigleaf periwinkle Grows most vigorously in moist soil with only partial 

sun, "but it will grow in the deepest shade, even in poor soil" (Bailey 1914). It is liable to cold damage during hard winters (Stearn 1973). Hot, dry weather will cause it to die back. It is most frequently found as an escape in moist rich soils bordering gardens, lawns, roadsides, cemeteries, and shaded waste places, in localities where it has been planted extensively as ground cover (Muenscher 1955). 

perennial vine, subshrub