Lion's tail (Leonurus cardiaca)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to Oregon, east to Idaho and Montana; also in eastern North America.
Habitat: Disturbed ground, often in association with cities and towns where escaping cultivation.
Origin: Introduced from Eurasia
Flowers: June-September
Growth Duration: Perennial

Small-flower tamarisk (Tamarix parviflora)
Distribution: Occurring chiefly east of the Cascades crest in Washington; south-central British Columbia to California, east to the southern Rocky Mountains and southern Great Plains.
Habitat: Mostly in riparian areas in arid regions.
Origin: Introduced from southern Europe and northern Africa
Flowers: May-June
Growth Duration: Perennial

Camphor tansy (Tanacetum bipinnatum)
Distribution: Occurring west of the Cascades crest along the coast of Washington; Alaska to California, east across Canada to the Great Lakes region and northeastern North America.
Habitat: Sand dunes along the coast.
Origin: Native
Flowers: May-September
Growth Duration: Perennial

Dune tansy (Tanacetum bipinnatum)
Distribution: Occurring west of the Cascades crest along the coast of Washington; Alaska to California, east across Canada to the Great Lakes region and northeastern North America.
Habitat: Sand dunes along the coast.
Origin: Native
Flowers: May-September
Growth Duration: Perennial

Mountain tansymustard (Descurainia incana)
Distribution: Occurring east of the Casades crest in Washington; Alaska to California, east to the Rocky Mountains, northern Great Plains, Great Lakes region, and northeastern North America.
Habitat: Sagebrush and confier forest openings from low to middle elevations.
Origin: Native
Flowers: April-June
Growth Duration: Annual

Narrow tansymustard (Descurainia longepedicellata)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to Oregon and Nevada, east to the Rocky Mountains from Montana to Arizona, but not New Mexico.
Habitat: Moderately dry forest openings and sagebrush desert.
Origin: Native
Flowers: April-June
Growth Duration: Annual

Sagebrush tansymustard (Descurainia nelsonii)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to Montana, Wyoming, Idaho, and Nevada.
Habitat: Sagrebrush desert to open montane forests.
Origin: Native
Flowers: May-June
Growth Duration: Annual

Western tansymustard (Descurainia pinnata)
Distribution: Occurring chiefly east of the Cascades crest in Washington; British Columbia to California, east across North America to the Atlantic Coast.
Habitat: Weedy native of fairly dry, open ground.
Origin: Native
Flowers: April-July
Growth Duration: Annual

Smooth tare (Vicia tetrasperma)
Distribution: Occurring west of the Cascades crest in Washington; southwestern British Columbia to California, also in northern Idaho and western Montana.
Habitat: Roadsides, fields, forest edge, wastelots, and other disturbed areas.
Origin: Introduced from Europe
Flowers: May-August
Growth Duration: Annual

Tare (Vicia sativa)
Distribution: Occurring on both sides of the Cascades crest and east in the Columbia River Gorge in Washington; Alaska to California, east across most of North America to the Atlantic Coast.
Habitat: Roadsides, fields, forest edges, thickets, lawns, wastelots, and other disturbed open areas.
Origin: Introduced from Eurasia
Flowers: April-July
Growth Duration: Annual

Grassy tarplant (Madia gracilis)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to Montana, Idaho, Nevada, and Utah.
Habitat: Dry, open areas from shrub-steppe to middle elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Annual

Little tarplant (Madia exigua)
Distribution: Occurring on both sides of the Cascades crest in Washington, but more common east of the crest; British Columbia to California, east to Montana, Idaho, and Nevada.
Habitat: Dry, open woods, grasslands, roadsides, and other open areas where often disturbed, from the plains and foothills, occasionally up to middle elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Annual

Smallhead tarplant (Hemizonella minima)
Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to California, east to Montana and Nevada.
Habitat: Dry, open areas in sagebrush, grasslands, and ponderosa pine forest openings.
Origin: Native
Flowers: May-July
Growth Duration: Annual

Tarragon (Artemisia dracunculus)
Distribution: Occurring east of the Cascades crest in Washington; Alaska to California, east to the Great Plains and Great Lakes region.
Habitat: Sagebrush desert to ponderosa pine forest openings at middle elevations.
Origin: Native
Flowers: July-October
Growth Duration: Perennial

Cluster tarweed (Madia glomerata)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains and across northern U.S. and southern Canada to the Atlantic Coast.
Habitat: Common in dry, open places from sagebrush plains to middle elevations in the mountains.
Origin: Native
Flowers: July-September
Growth Duration: Annual

Common tarweed (Madia gracilis)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to Montana, Idaho, Nevada, and Utah.
Habitat: Dry, open areas from shrub-steppe to middle elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Annual

Lemon tarweed (Madia citriodora)
Distribution: Occurring east of the Cascades crest in Washington; Washington to California, east to Nevada.
Habitat: Dry, open hillsides and foothills.
Origin: Native
Flowers: May-June
Growth Duration: Annual

Little tarweed (Madia exigua)
Distribution: Occurring on both sides of the Cascades crest in Washington, but more common east of the crest; British Columbia to California, east to Montana, Idaho, and Nevada.
Habitat: Dry, open woods, grasslands, roadsides, and other open areas where often disturbed, from the plains and foothills, occasionally up to middle elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Annual

Slender tarweed (Madia gracilis)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to Montana, Idaho, Nevada, and Utah.
Habitat: Dry, open areas from shrub-steppe to middle elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Annual

Smallhead tarweed (Hemizonella minima)
Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to California, east to Montana and Nevada.
Habitat: Dry, open areas in sagebrush, grasslands, and ponderosa pine forest openings.
Origin: Native
Flowers: May-July
Growth Duration: Annual

Large flowered tasselflower (Brickellia grandiflora)
Distribution: Occasional east of the Cascades in Washington and Oregon.
Habitat: Openings in woods at moderate elevations, sometimes in plains.
Origin: Native
Flowers: July-October
Growth Duration: Perennial

California tea (Rupertia physodes)
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California, disjunct in northeastern Oregon and adjacent Idaho.
Habitat: Prairie and forest edges at low elevations.
Origin: Native
Flowers: May-June
Growth Duration: Perennial

Western Labrador tea (Rhododendron neoglandulosum)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains.
Habitat: Montane to alpine bogs, lakes, ponds, and seasonally moist slopes.
Origin: Native
Flowers: June-September
Growth Duration: Perennial

Teasel (Dipsacus fullonum)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east across most of North America.
Habitat: Disturbed, open areas often where at least seasonally wet; low to moderate elevations.
Origin: Introduced
Flowers: June-December
Growth Duration: Biennial

Thalecress (Arabidopsis thaliana)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east across most of North America.
Habitat: Disturbed areas, particularly near cities and towns.
Origin: Introduced from Eurasia
Flowers: March-May
Growth Duration: Annual

Entire-leaved thelypody (Thelypodium integrifolium)
Distribution: Occurring east of the Cascades crest in Washington; Washington to California, east to northern Great Plains.
Habitat: Sagebrush plains to streambanks in the lower mountains.
Origin: Native
Flowers: June-August
Growth Duration: Perennial

Many flowered thelypody (Thelypodium milleflorum)
Distribution: Occurring east of the Cascades crest in Washington; southern British Columbia to Nevada, east to Idaho.
Habitat: Rock cliffs and dry, rocky areas in sagebrush desert.
Origin: Native
Flowers: April-July
Growth Duration: Biennial

Thick-leaved thelypody (Thelypodium laciniatum)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to Idaho and Nevada.
Habitat: Rock cliffs and dry, rocky areas.
Origin: Native
Flowers: April-July
Growth Duration: Biennial

Thimbleberry (Rubus parviflorus)
Distribution: Widely distributed on both sides of the Cascades crest in Washington; Alaska to California, east to Alberta, the Rocky Mountains, and Great Lakes region.
Habitat: Forest openings and edge, thickets, meadows, and riparian corridors from sea level to the subalpine.
Origin: Native
Flowers: April-July
Growth Duration: Perennial

Bull thistle (Cirsium vulgare)
Distribution: Widely distributed on both sides of the Cascades crest in Washington; British Columbia to California, east to the Atlantic Coast.
Habitat: Roadsides, fields, forest edge, ditches, balds, prairies, wastelots, and other disturbed, open areas.
Origin: Introduced from Eurasia
Flowers: June-September
Growth Duration: Biennial

Clustered thistle (Cirsium brevistylum)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to northern California, east to Montana.
Habitat: Slopes, open forest, and moist meadows from low to middle elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Annual, Biennial, Perennial

Cotton thistle (Onopordum acanthium)
Distribution: Occurring chiefly east of the Cascades crest and in the Columbia River Gorge in Washington; British Columbia to California, east across most of North America to the Atlantic Coast.
Habitat: Noxious weed of dry, open areas and stream banks.
Origin: Introduced from Eurasia
Flowers: June-August
Growth Duration: Biennial

Edible thistle (Cirsium edule)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to Oregon.
Habitat: Forest openings and edge, meadows, roadsides, and other open areas at low to middle elevations in the mountains.
Origin: Native
Flowers: July-September
Growth Duration: Biennial, Perennial

Few-leaf thistle (Cirsium remotifolium)
Distribution: Occurring west of the Cascades crest and east in the Columbia River Gorge in Washington; Washington to California.
Habitat: Meadows, stream banks, open for, brushy slopes, from low to middle elevations in the mountains.
Origin: Native
Flowers: June-September
Growth Duration: Biennial, Perennial

Hooker's thistle (Cirsium hookerianum)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to Washington, east to Alberta, Montana, and Wyoming.
Habitat: Moist lowlands, open slopes and fields.
Origin: Native
Flowers: July-August
Growth Duration: Perennial

Musk thistle (Carduus nutans)
Distribution: Occurring in scattered locations on both sides of the Cascades crest in Washington; British Columbia to California, east to the Atlantic Coast.
Habitat: Roadsides, fields, ditches, wastelots, and other disturbed, open areas.
Origin: Introduced from Eurasia
Flowers: June-October
Growth Duration: Biennial, Perennial

Pacific fringed thistle (Cirsium remotifolium)
Distribution: Occurring west of the Cascades crest and east in the Columbia River Gorge in Washington; Washington to California.
Habitat: Meadows, stream banks, open for, brushy slopes, from low to middle elevations in the mountains.
Origin: Native
Flowers: June-September
Growth Duration: Biennial, Perennial

Plumeless thistle (Carduus acanthoides)
Distribution: Occurring east of the Cascades crest in northeastern Washington; British Columbia to Washington, also in California, east to the northern Rocky Mountains, Great Plains, and eastern North America.
Habitat: Roadsides, fields, ditches, and other disturbed, open areas.
Origin: Introduced from Europe
Flowers: July-October
Growth Duration: Biennial

Russian thistle (Salsola tragus)
Distribution: Occurring chiefly east of the Cascades crest in Washington, where widely distributed; southern British Columbia to California, east across North America to the Atlantic Coast.
Habitat: Roadside, meadows, fields, wastelots, and other disturbed open areas from low to middle elevations.
Origin: Introduced from Eurasia
Flowers: June-August
Growth Duration: Annual

Scots thistle (Onopordum acanthium)
Distribution: Occurring chiefly east of the Cascades crest and in the Columbia River Gorge in Washington; British Columbia to California, east across most of North America to the Atlantic Coast.
Habitat: Noxious weed of dry, open areas and stream banks.
Origin: Introduced from Eurasia
Flowers: June-August
Growth Duration: Biennial

Slender flowered thistle (Carduus tenuiflorus)
Distribution: Occurring west of the Cascades crest in southwestern Washington; Washington to California, also in the eastern U.S.
Habitat: Roadsides, fields, ditches, wastelots, and other disturbed areas at low elevations.
Origin: Introduced from Europe
Flowers: June-July
Growth Duration: Annual

Wavy leaf thistle (Cirsium undulatum)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to Michigan and Texas.
Habitat: Dry hillsides and plains at low elevations.
Origin: Native
Flowers: May-September
Growth Duration: Biennial, Perennial

White thistle (Cirsium hookerianum)
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to Washington, east to Alberta, Montana, and Wyoming.
Habitat: Moist lowlands, open slopes and fields.
Origin: Native
Flowers: July-August
Growth Duration: Perennial

Thompsongrass (Paspalum distichum)
Distribution: Occurring chiefly along the lower Columbia River corridor in Washington; British Columbia to California, east across most of North America to the Atlantic Coast.
Habitat: Along ditches and streams where the soil is moist much of the season.
Origin: Native
Flowers: August-October
Growth Duration: Perennial

Sacred thorn apple (Datura wrightii)
Distribution: Occurring chiefly east of the Cascades crest in Washington; Washington to California, east across most of North America to the Atlantic Coast.
Habitat: Disturbed, dry, open areas, roadsides, and waste places.
Origin: Introduced from Mexico
Flowers: June-August
Growth Duration: Annual

Narrow-leaved thoroughwort (Brickellia oblongifolia)
Distribution: Occurring east of the Cascades crest in Washington; southern British Columbia to California east to the Rocky Mountains.
Habitat: Dry, often rocky places from lowland sagebrush desert to middle elevations in the mountains.
Origin: Native
Flowers: May-August
Growth Duration: Perennial

Common three-square (Schoenoplectus pungens)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Atlantic Coast; Europe.
Habitat: Marshes and wet, low ground; tolerent of alkali.
Origin: Native
Flowers: May-August
Growth Duration: Perennial

Jersey thrift (Armeria arenaria)
Distribution: Occurring west of the Cascades crest in Washington; not known from elsewhere in North America.
Habitat: Roadsides, fields, ditches, and other disturbed open areas at low elevations.
Origin: Introduced from Europe
Flowers: April-July
Growth Duration: Perennial

White false tickhead (Eatonella nivea)
Distribution: Occurring east of the Cascades crest in central Washington; Washington to California, east to Idaho and Nevada.
Habitat: Dry, sandy, or volcanic desert areas.
Origin: Native
Flowers: May-July
Growth Duration: Annual

Lance-leaved tickseed (Coreopsis lanceolata)
Origin: Introduced

White daisy tidytips (Layia glandulosa)
Distribution: Occurring east of the Cascades crest in Washington; Washington to California, east to Idaho, Utah, Arizona and New Mexico.
Habitat: Dry, open areas from sagebrush desert to low elevations in the mountains.
Origin: Native
Flowers: April-June
Growth Duration: Annual

Timothy (Phleum pratense)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.
Habitat: Disturbed areas, especially moist, open meadows, from coast to midmontane.
Origin: Introduced from Eurasia
Flowers: May-July
Growth Duration: Perennial

Bastard toadflax (Comandra umbellata)
Distribution: Occurring chiefly east of the Cascades crest in Washington; Yukon Territory to California, east across North America to the Atlantic Coast.
Habitat: Dry to moist-but-sandy soil, sea level to subalpine; common in the shrub-steppe.
Origin: Native
Flowers: April-August
Growth Duration: Perennial

Broomleaf toadflax (Linaria genistifolia)
Distribution: Occurring east of the Cascades crest in eastern Washington; British Columbia to northeastern Oregon; in scattered localities across North America.
Habitat: Open areas roadsides, fields, wastelots, forest openings, typically where disturbed.
Origin: Introduced from Eurasia and northern Africa
Flowers: June-September
Growth Duration: Perennial

Dalmation toadflax (Linaria dalmatica)
Distribution: Occurring chiefly east of the Cascades crest in Washington; Yukon Territory to California, east across much of North America to the Atlantic Coast.
Habitat: Open areas roadsides, fields, wastelots, forest openings, typically where disturbed.
Origin: Introduced Eurasia and northern Africa
Flowers: May-August
Growth Duration: Perennial

Ivy-leaved toadflax (Cymbalaria muralis)
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California, scattered eastward across North America to the Atlantic Coast where more broadly distributed.
Habitat: Roadsides, retaining walls, wastelots, and other disturbed open areas at low elevation.
Origin: Introduced from Eurasia
Flowers: April-October
Growth Duration: Annual

Old field toadflax (Nuttallanthus canadensis)
Distribution: Occurring west of the Cascades crest in Washington; southwestern British Columbia and Puget Trough islands to western Oregon and California.
Habitat: Prairies, balds, and other open areas at low elevations.
Origin: Native
Flowers: May-June
Growth Duration: Annual

Texas toadflax (Nuttallanthus texanus)
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California, east to Sasketchewan and across much of the U.S. except the upper Midwest and Northeast.
Habitat: Prairies, grasslands, and balds.
Origin: Native
Flowers: May-June
Growth Duration: Annual

Jersey rabbit tobacco (Pseudognaphalium luteoalbum)
Distribution: Occurring in scattered locations on both sides of the Cascades crest in Washington; Washington to California, east across the southern U.S. to Florida, also in New York.
Habitat: Roadsides, fields, wastelots, and other disturbed areas at low elevations.
Origin: Introduced from Eurasia
Flowers: June-October
Growth Duration: Annual

Tobacco-brush (Ceanothus velutinus)
Distribution: Widely distributed on both sides of the Cascades crest in Washington; British Columbia to California, east to Alberta, South Dakota, Wyoming, and Colorado.
Habitat: Moist to dry open forests, low to mid-elevations in the mountains.
Origin: Native
Flowers: June-September
Growth Duration: Perennial

Tocalote (Centaurea melitensis)
Distribution: Occurring chiefly west of the Cascades in Washington; British Columbia to California and Mexico, east to Texas and eastern North America.
Habitat: Roadsides, meadows, balds, fields, ditches, wastelots, and other disturbed, open areas at low to middle elevations.
Origin: Introduced from the Mediterranean region
Flowers: June-September
Growth Duration: Annual, Biennial

Wild tomatillo (Physalis longifolia)
Distribution: Occurring chiefly east of the Cascades in Washington; British Columbia to California, east across North America to the Atlantic Coast.
Habitat: Weed of cultivated fields and waste places.
Origin: Both native and introduced
Flowers: June-September
Growth Duration: Perennial

Large-flowered tonella (Tonella floribunda)
Distribution: Occurring east of the Cascades crest in southern Washington; southern Washington to Oregon, east to Idaho.
Habitat: Open, often rocky places, at low elevations.
Origin: Native
Flowers: April-June
Growth Duration: Annual

Grand hound (Adelinia grandis)
Distribution: Occurring west of the Cascades crest and in the Columbia River Gorge in Washington; Washington to California.
Habitat: Forest openings and meadows at low to moderate elevations.
Origin: Native
Flowers: April-May
Growth Duration: Perennial

Nuttall's toothwort (Cardamine nuttallii)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California.
Habitat: Seasonally moist soils of forest openings to forest understory, from low to moderate elevations.
Origin: Native
Flowers: March-May
Growth Duration: Perennial

Small-flowered touch-me-not (Impatiens parviflora)
Distribution: Currently (2016) known from west of the Cascades crest in Washington from King County (only); southwestern British Columbia, western Washington and northwestern Oregon; also occurring in eastern North America.
Habitat: Disturbed forest edge and understory at low elevations, often where at least seasonally moist.
Origin: Introduced from Asia
Flowers: June-July
Growth Duration: Annual

Showy townsendia (Townsendia florifera)
Distribution: Occurring east of the Cascades crest in Washington; Washington to Oregon and Nevada, east to Montana, Wyoming, and Utah.
Habitat: Dry-open places in the plains and foothills, often with sagebrush.
Origin: Native
Flowers: May-July
Growth Duration: Perennial

Traveler's-joy (Clematis vitalba)
Distribution: Occurring chiefly west of the Cascades crest in Washington; British Columbia to Oregon, also in scattered locations in eastern North America.
Habitat: Forest edge, hillsides, parks, wastelots, and other disturbed sites.
Origin: Introduced; native to Europe and Africa
Flowers: June-September
Growth Duration: Perennial

American bird's-foot trefoil (Acmispon americanus)
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to Rocky Mountains, south to Mexico.
Habitat: Chiefly in sandy to rocky, exposed or wooded areas, more common at low elevations
Origin: Native
Flowers: April-September
Growth Duration: Annual

Bird's-foot trefoil (Lotus corniculatus)
Distribution: Occurring on both sides of the Cascades crest in Washington; widely distributed throughout most of North America.
Habitat: Open, mesic to wet areas, typically where disturbed.
Origin: Introduced
Flowers: May-September
Growth Duration: Perennial

Large bird's-foot trefoil (Lotus uliginosus)
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California, east to Idaho; east across Canada to Nova Scotia; scattered localities in eastern U.S.
Habitat: Moist to wet disturbed areas, roadsides, abandoned lots, and coastal tidelands.
Origin: Introduced from Europe
Flowers: May-July
Growth Duration: Perennial

Narrowleaf bird's-foot trefoil (Lotus tenuis)
Distribution: Occurring in scattered locations on both sides of the Cascades crest in Washington; British Columbia to California, east to the Great Plains, also in eastern North America.
Habitat: Fields, roadsides, wastelots, and other disturbed areas
Origin: Introduced from Eurasia
Flowers: May-July
Growth Duration: Perennial

Riverbar bird's-foot-trefoil (Acmispon denticulatus)
Distribution: Occurring on both sides of the Cascades in Washington; southern British Columbia to California, disjunct in southern Idaho and southwestern Utah.
Habitat: Sandy to rocky soil in open areas at low to moderate elevations.
Origin: Native
Flowers: April-June
Growth Duration: Annual

Seaside bird's-foot-trefoil (Hosackia gracilis)
Distribution: Occurring west of the Cascades crest in Washington; Washington to California.
Habitat: On moist soil, from near sea level to lower elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Perennial

Small-flowered bird's-foot trefoil (Acmispon parviflorus)
Distribution: Occurring chiefly west of the Cascades crest and east in the Columbia River Gorge in Washington; British Columbia to California.
Habitat: Open slopes and sandy flats, seashore into the mountains.
Origin: Native
Flowers: April-September
Growth Duration: Annual

Giant trillium (Trillium albidum)
Distribution: Occurring west of the Cascades crest in Washington; Washington to California.
Habitat: Moist forests, oak-ash woodlands, thickets, and fields at low elevations.
Origin: Native
Flowers: April-June
Growth Duration: Perennial

Sessile trillium (Trillium albidum)
Distribution: Occurring west of the Cascades crest in Washington; Washington to California.
Habitat: Moist forests, oak-ash woodlands, thickets, and fields at low elevations.
Origin: Native
Flowers: April-June
Growth Duration: Perennial

Western trillium (Trillium ovatum)
Distribution: Occurring chiefly west of the Cascades crest in Washington; British Columbia to California.
Habitat: Open to dense moist forests at low to mid-elevations, often where boggy in the spring.
Origin: Native
Flowers: March-June
Growth Duration: Perennial

White trillium (Trillium ovatum)
Distribution: Occurring chiefly west of the Cascades crest in Washington; British Columbia to California.
Habitat: Open to dense moist forests at low to mid-elevations, often where boggy in the spring.
Origin: Native
Flowers: March-June
Growth Duration: Perennial

Nodding trisetum (Trisetum cernuum)
Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to California, east to Alberta, Idaho, and Montana.
Habitat: Moist to dry meadows and forest, stream banks, springs, and rocky slopes.
Origin: Native
Flowers: May-July
Growth Duration: Perennial

Large-flowered tritelia (Triteleia grandiflora)
Distribution: Occurring chiefly east of the Cascades crest in Washington, but also occurring in the north Puget Sound area; British Columbia to California, east to Montana, Idaho, Wyoming and Utah.
Habitat: Prairies, grasslands, balds and forest openings, often where seasonally dry, from the coast to middle elevations in the mountains.
Origin: Native
Flowers: April-June
Growth Duration: Perennial

Yellow trumpet (Sarracenia flava)
Distribution: Occurring west of the Cascades crest, where intentionally planted; native in the southeastern United States.
Habitat: Swamps, bogs and seeps.
Origin: Introduced from southeast United States
Flowers: May-June
Growth Duration: Perennial

Common tule (Schoenoplectus acutus)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east throughout all of North America except southeastern U.S.
Habitat: Pond and lake margins, wetland and riparian areas.
Origin: Native
Flowers: May-July
Growth Duration: Perennial

Tumbleweed (Amaranthus albus)
Distribution: Occurring chiefly east of the Cascades crest in Washington; British Columbia to California, east across much of North America to the Atlantic Coast.
Habitat: Dry, disturbed areas.
Origin: Introduced from tropical America
Flowers: June-September
Growth Duration: Annual

Turkey peas (Lomatium linearifolium)
Distribution: Occurring east of the Cascades crest in Washington; central Washington to north-central Oregon, east to Montana and Wyoming.
Habitat: Open slopes and ridges, from low to middle elevations.
Origin: Native
Flowers: March-May
Growth Duration: Perennial

Wild turnip (Brassica rapa)
Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to California, east to the Atlantic Coast.
Habitat: Roadsides, fields, ditches, wastelots and other disturbed open areas.
Origin: Introduced from Europe
Flowers: April-Septemeber
Growth Duration: Annual, Biennial

Broad-lip twayblade (Neottia convallarioides)
Distribution: Occurring on both sides of the Cascades crest in the forested and mountainous areas of Washington; Alaska to California, east to the Rocky Mountains, and from the Great Lakes region to northeastern North America.
Habitat: Moist forests and wet meadows, from low elevations to the subalpine.
Origin: Native
Flowers: June-August
Growth Duration: Perennial

Loesel's twayblade (Liparis loeselii)
Distribution: Occurring east of the Cascades crest in Washington in south-central Washington; Northwest Territory to Washington, east to Montana; also from Canadian Great Plains to eastern North America where more common; also in western and central Europe.
Habitat: Around springs and in bogs.
Origin: Native
Flowers: July-August
Growth Duration: Perennial

Northwestern twayblade (Neottia banksiana)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to Alberta and Wyoming.
Habitat: Moist forests and wet meadows, lowlands to subalpine elevations
Origin: Native
Flowers: June-August
Growth Duration: Perennial

Twinflower (Linnaea borealis)
Distribution: Widely distributed in forested and mountainous areas on both sides of the Cascades crest in Washington; Alaska to California, east in North America to the Atlantic Coast; circumboreal.
Habitat: Open forest, forest edges, and peatlands from low elevations to the alpine.
Origin: Native
Flowers: May-September
Growth Duration: Perennial

Common twinpod (Physaria didymocarpa)
Distribution: Occurring east of the Cascades crest in northeastern Washington; southeastern British Columbia to northeastern Washington, east to Alberta and Wyoming.
Habitat: Talus, gravel bars, outcrops, dry slopes, prairies, road cuts
Origin: Native
Flowers: June-August
Growth Duration: Perennial

Oregon twinpod (Physaria oregona)
Distribution: Occurring east of the Cascades crest in southeastern Washington; Washington to Oregon, east to Idaho.
Habitat: Dry areas including rocky slopes, gravel banks, and stream shores.
Origin: Native
Flowers: April-June
Growth Duration: Perennial

Clasp-leaf twisted-stalk (Streptopus amplexifolius)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains, also in northeastern North America.
Habitat: Open to dense moist forests from low elevations to subalpine.
Origin: Native
Flowers: May-July
Growth Duration: Perennial

Rosy twisted-stalk (Streptopus lanceolatus)
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to Oregon, east to Alberta and Montana (but not Idaho); also from the Great Lakes region east to the Atlantic Coast.
Habitat: Streambanks and damp woods at moderate to high elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Perennial