Vascular Plants
Includes all flowering plants, conifers, ferns and fern-allies.
Browse by scientific name:
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Scientific names beginning with O:
27 genera
58 species, 20 subspecies and varieties
58 species, 20 subspecies and varieties
Show only taxa with photos
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Index to genera:
Odontites, Oemleria, Oenanthe, Oenothera, Olsynium, Onobrychis, Ononis, Onopordum, Ophioglossum, Oplopanax, Opuntia, Oreocarya, Oreopteris, Oreostemma, Origanum, Ornithogalum, Orobanche, Orthilia, Orthocarpus, Oryzopsis, Osmorhiza, Oxalis, Oxybasis, Oxyria, Oxytheca, Oxytropis, OzomelisOemleria cerasiformis – oso-berry, Indian plum
Distribution: Occurring west of the Cascades crest and east in the Columbia River Gorge in Washington; British Columbia to California.
Habitat: Moist to dry, open forest, forest edge, and stream bank thickets at low elevation.
Origin: Native
Flowers: February-April
Growth Duration: Perennial
Distribution: Occurring west of the Cascades crest and east in the Columbia River Gorge in Washington; British Columbia to California.
Habitat: Moist to dry, open forest, forest edge, and stream bank thickets at low elevation.
Origin: Native
Flowers: February-April
Growth Duration: Perennial
Oenanthe sarmentosa – oenanthe, Pacific water-dropwort, American water-parsley, Pacific water-parsley
Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to California.
Habitat: Low elevation wet areas, often in standing water.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to California.
Habitat: Low elevation wet areas, often in standing water.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Oenothera biennis – King's-cureall
Distribution: Occurring on both sides of the Cascades crest in Washington; widely distributed throughout much of North America.
Habitat: Meadows and stream banks, from the plains to the lower mountains, typically where disturbed.
Origin: Introduced from Europe
Flowers: June-August
Growth Duration: Biennial
Distribution: Occurring on both sides of the Cascades crest in Washington; widely distributed throughout much of North America.
Habitat: Meadows and stream banks, from the plains to the lower mountains, typically where disturbed.
Origin: Introduced from Europe
Flowers: June-August
Growth Duration: Biennial
Oenothera cespitosa
Distribution: Occuring sporadically throughout central and eastern Washington; widespread throughout much of western U.S. and central Canada.
Habitat: Talus slopes, road cuts, and dry hills.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occuring sporadically throughout central and eastern Washington; widespread throughout much of western U.S. and central Canada.
Habitat: Talus slopes, road cuts, and dry hills.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
• ssp. cespitosa – butte primrose, fragrant evening primrose, rock rose
• ssp. marginata – fragrant evening-primrose
Oenothera curtiflora – small-flowered gaura, velvet weed
Distribution: Occurring east of the Cascades crest in Washington; south-central Washington to eastern Oregon, Nevada, and Arizona, east to North Dakota,, Iowa, and Louisiana; introduced in California and the eastern U.S., South America, Asia, and Australia.
Habitat: Meadows, stream banks, roadsides, sandy or rocky slopes, often where disturbed.
Origin: Introduced from the central U.S.
Flowers: June-September
Growth Duration: Annual
Distribution: Occurring east of the Cascades crest in Washington; south-central Washington to eastern Oregon, Nevada, and Arizona, east to North Dakota,, Iowa, and Louisiana; introduced in California and the eastern U.S., South America, Asia, and Australia.
Habitat: Meadows, stream banks, roadsides, sandy or rocky slopes, often where disturbed.
Origin: Introduced from the central U.S.
Flowers: June-September
Growth Duration: Annual
Oenothera elata – Hooker's evening primrose
Distribution: Occurring chiefly east of the Cascades crest in Washington; Washington to California, east to the Rocky Mountains and southern Great Plains in the U.S.
Habitat: Sagebrush hills to mid elevations in the mountains, generally where moist.
Origin: Native
Flowers: June-September
Growth Duration: Biennial, Perennial
Distribution: Occurring chiefly east of the Cascades crest in Washington; Washington to California, east to the Rocky Mountains and southern Great Plains in the U.S.
Habitat: Sagebrush hills to mid elevations in the mountains, generally where moist.
Origin: Native
Flowers: June-September
Growth Duration: Biennial, Perennial
Oenothera flava – long-tubed evening primrose
Distribution: Occurring east of the Cascades crest, where known historically from the south-central area. Washington to California, east to the Rocky Mountains and Great Plains.
Habitat: Hard-packed soil in swales or around vernal pools in the plains and lower foothills.
Origin: Native
Flowers: July-August
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest, where known historically from the south-central area. Washington to California, east to the Rocky Mountains and Great Plains.
Habitat: Hard-packed soil in swales or around vernal pools in the plains and lower foothills.
Origin: Native
Flowers: July-August
Growth Duration: Perennial
Oenothera glazioviana – red-sepal evening-primrose
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California; also in scattered locations in the eastern U.S.
Habitat: Disturbed soil.
Origin: Introduced from Europe
Flowers: June-September
Growth Duration: Biennial
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California; also in scattered locations in the eastern U.S.
Habitat: Disturbed soil.
Origin: Introduced from Europe
Flowers: June-September
Growth Duration: Biennial
Oenothera pallida – pale evening-primrose
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to Arizona, east to the Rocky Mountains and Texas.
Habitat: Dry, sandy or gravelly soil, commonly on dunes at low elevations.
Origin: Native
Flowers: May-July (September-October)
Growth Duration: Biennial, Perennial
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to Arizona, east to the Rocky Mountains and Texas.
Habitat: Dry, sandy or gravelly soil, commonly on dunes at low elevations.
Origin: Native
Flowers: May-July (September-October)
Growth Duration: Biennial, Perennial
• ssp. pallida – pale evening primrose
Oenothera villosa – common evening primrose
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east across North America to the Atlantic Coast.
Habitat: Roadsides, shores, riparian zones, ditches, disturbed ground.
Flowers: June-August
Growth Duration: Biennial
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east across North America to the Atlantic Coast.
Habitat: Roadsides, shores, riparian zones, ditches, disturbed ground.
Flowers: June-August
Growth Duration: Biennial
• ssp. strigosa – hairy common evening primrose
Olsynium douglasii – grass-widow, purple-eyed grass-widow
Distribution: Occurring on both sides of the Cascades crest in Washington, but more widespread east of the crest; British Columbia to California, east to Idaho, Nevada, and Utah.
Habitat: Coastal bluffs, prairies, open rocky areas, oak and ponderosa pine woodlands, sagebrush and juniper desert, where moist in early spring.
Origin: Native
Flowers: January-June
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington, but more widespread east of the crest; British Columbia to California, east to Idaho, Nevada, and Utah.
Habitat: Coastal bluffs, prairies, open rocky areas, oak and ponderosa pine woodlands, sagebrush and juniper desert, where moist in early spring.
Origin: Native
Flowers: January-June
Growth Duration: Perennial
• var. douglasii – purple-eyed grass-widow
• var. inflatum – grass-widow, purple-eyed grass-widow
Onobrychis viciifolia – holy-clover, saintfoin, sandfain
Distribution: Occurring east of the Cascades crest in Washington; Alaska to California, east to the Great Plains, also in eastern North America,
Habitat: Roadsides, fields, wastelots, and other disturbed areas.
Origin: Introduced
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in Washington; Alaska to California, east to the Great Plains, also in eastern North America,
Habitat: Roadsides, fields, wastelots, and other disturbed areas.
Origin: Introduced
Flowers: June-August
Growth Duration: Perennial
Ononis spinosa – restharrow
Distribution: Known from Klickitat County in Washington; south-central Washington to adjacent Oregon, also in scattered locations in eastern North America.
Origin: Introduced from Europe
Flowers: June-August
Distribution: Known from Klickitat County in Washington; south-central Washington to adjacent Oregon, also in scattered locations in eastern North America.
Origin: Introduced from Europe
Flowers: June-August
• ssp. maritima – common restharrow
Onopordum acanthium – cotton thistle, Scotch thistle, Scots thistle
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
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
• ssp. acanthium – Scotch thistle, cotton thistle, Scots thistle
Ophioglossum pusillum – northern adder's-tongue
Distribution: Occurring chiefly east of the Cascades crest in Washington; Alaska to California, east to Idaho and Montana, northern Great Plains, Great Lakes region, and northeastern North America.
Habitat: Moist meadows and edges of marshes or fens, from the coast to middle elevations in the mountains.
Origin: Native
Spores: May-July
Growth Duration: Perennial
Distribution: Occurring chiefly east of the Cascades crest in Washington; Alaska to California, east to Idaho and Montana, northern Great Plains, Great Lakes region, and northeastern North America.
Habitat: Moist meadows and edges of marshes or fens, from the coast to middle elevations in the mountains.
Origin: Native
Spores: May-July
Growth Duration: Perennial
Oplopanax horridus – devil's-club
Distribution: Widely distributed throughout the forested areas on both sides of the Cascades crest in Washington; Alaska to Oregon, east to Alberta and Montana, also in the Great Lakes region.
Habitat: Moist woods at mid-elevations, especially along streams.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Widely distributed throughout the forested areas on both sides of the Cascades crest in Washington; Alaska to Oregon, east to Alberta and Montana, also in the Great Lakes region.
Habitat: Moist woods at mid-elevations, especially along streams.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Opuntia columbiana – Columbia prickly-pear
Distribution: Occurring east of the Cascades crest in Washington; south-central British Columbia to eastern Oregon, east to western and southern Idaho.
Habitat: From sagebrush plains and foothills to lower elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in Washington; south-central British Columbia to eastern Oregon, east to western and southern Idaho.
Habitat: From sagebrush plains and foothills to lower elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Opuntia fragilis – brittle prickly-pear, little prickly-pear
Distribution: Occurring chiefly west of the Cascades crest in Washington; British Columbia to California, east the Rocky Mountains, Great Plains, and Great Lakes region.
Habitat: Dry, open, often sandy soil.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring chiefly west of the Cascades crest in Washington; British Columbia to California, east the Rocky Mountains, Great Plains, and Great Lakes region.
Habitat: Dry, open, often sandy soil.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Opuntia phaeacantha
Distribution: Occurring east of the Cascades crest in south-central Washington, where likely intentionally introduced; California to Kansas, south to Texas.
Habitat: Rocky, disturbed areas.
Origin: Introduced from southeastern U.S.
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in south-central Washington, where likely intentionally introduced; California to Kansas, south to Texas.
Habitat: Rocky, disturbed areas.
Origin: Introduced from southeastern U.S.
Flowers: June-August
Growth Duration: Perennial
Oreocarya glomerata – cockscomb oreocarya
Distribution: Occurring east of the Cascades crest and in the Columbia River Gorge in Washington; southern British Colombia to California, east to the northern Great Plains and Colorado.
Habitat: Dry, open places in the valleys, plains and foothills, occasionally higher.
Origin: Native
Flowers: April-July
Growth Duration: Biennial, Perennial
Distribution: Occurring east of the Cascades crest and in the Columbia River Gorge in Washington; southern British Colombia to California, east to the northern Great Plains and Colorado.
Habitat: Dry, open places in the valleys, plains and foothills, occasionally higher.
Origin: Native
Flowers: April-July
Growth Duration: Biennial, Perennial
Oreocarya leucophaea – gray oreocarya
Distribution: Occurring east of the Cascades in central and south-central Washington, where endemic.
Habitat: Dry, usually sandy places at low elevations.
Origin: Native
Flowers: May-June
Growth Duration: Biennial, Perennial
Distribution: Occurring east of the Cascades in central and south-central Washington, where endemic.
Habitat: Dry, usually sandy places at low elevations.
Origin: Native
Flowers: May-June
Growth Duration: Biennial, Perennial
Oreocarya spiculifera – Snake River cat's-eye, Snake River oreocarya
Distribution: Occurring east of the Cascades crest in Washington; Washington to Oregon and Nevada, east to Idaho, Montana, Wyoming, and Utah.
Habitat: Dry, open slopes and flats in the plains, valleys and foothills.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in Washington; Washington to Oregon and Nevada, east to Idaho, Montana, Wyoming, and Utah.
Habitat: Dry, open slopes and flats in the plains, valleys and foothills.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Oreocarya thompsonii – Thompson's cat's-eye, Thompson's oreocarya
Distribution: Occurring east of the Cascades crest in Washington, where endemic to the Wenatchee Mountains and nearby areas.
Habitat: Middle elevations in the mountains
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in Washington, where endemic to the Wenatchee Mountains and nearby areas.
Habitat: Middle elevations in the mountains
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Oreopteris quelpartensis – mountain fern, queen's-veil maiden fern
Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to the Cascades of central Washington; also in eastern Asia.
Habitat: Wet cliffs and rocky slopes, sea level to subalpine.
Origin: Native
Growth Duration: Perennial
Distribution: Occurring chiefly west of the Cascades crest in Washington; Alaska to the Cascades of central Washington; also in eastern Asia.
Habitat: Wet cliffs and rocky slopes, sea level to subalpine.
Origin: Native
Growth Duration: Perennial
Oreostemma alpigenum – alpine aster
Distribution: Occurring in the Cascades and Olympic mountains in Washington; British Columbia to California, east to Montana, Wyoming, and Nevada.
Habitat: Alpine meadows, slopes, and rocky areas.
Origin: Native
Flowers: June-September
Growth Duration: Perennial
Distribution: Occurring in the Cascades and Olympic mountains in Washington; British Columbia to California, east to Montana, Wyoming, and Nevada.
Habitat: Alpine meadows, slopes, and rocky areas.
Origin: Native
Flowers: June-September
Growth Duration: Perennial
• var. alpigenum – alpine aster, tundra mountaincrown
Origanum vulgare – wild marjoram
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California, east to Idaho; also in eastern North America.
Habitat: Escaped from cultivation along roadsides and in disturbed soil.
Origin: Introduced from Eurasia
Flowers: July-September
Growth Duration: Perennial
Distribution: Occurring west of the Cascades crest in Washington; British Columbia to California, east to Idaho; also in eastern North America.
Habitat: Escaped from cultivation along roadsides and in disturbed soil.
Origin: Introduced from Eurasia
Flowers: July-September
Growth Duration: Perennial
Ornithogalum umbellatum – nap-at-noon, garden star-of-Bethlehem
Distribution: Occurring in scattered locations on both sides of the Cascades crest in Washington; British Columbia to California, east to Idaho and Utah, also from Great Plains to eastern North America.
Habitat: Roadsides, open forests, fields, wastelots, and other disturbed areas at low elevation.
Origin: Introduced from Eurasia
Flowers: April-May
Growth Duration: Perennial
Distribution: Occurring in scattered locations on both sides of the Cascades crest in Washington; British Columbia to California, east to Idaho and Utah, also from Great Plains to eastern North America.
Habitat: Roadsides, open forests, fields, wastelots, and other disturbed areas at low elevation.
Origin: Introduced from Eurasia
Flowers: April-May
Growth Duration: Perennial
Orobanche minor – hellroot
Distribution: Occurring in scattered locations west of the Cascades crest in Washington; Washington to Oregon, and reported from Idaho; also in Texas and along the East Coast of the U.S.
Habitat: Lawns, fields, pastures, forest edge, and other grassy areas at low elevations.
Origin: Introduced from Europe
Flowers: May-July
Growth Duration: Annual
Distribution: Occurring in scattered locations west of the Cascades crest in Washington; Washington to Oregon, and reported from Idaho; also in Texas and along the East Coast of the U.S.
Habitat: Lawns, fields, pastures, forest edge, and other grassy areas at low elevations.
Origin: Introduced from Europe
Flowers: May-July
Growth Duration: Annual
Orthilia secunda – one-sided pyrola, sidebells
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across Canada and the northern half of the United States to the Atlantic Coast.
Habitat: Common in coniferous woods at moderate to mid-elevationn in the mountains
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across Canada and the northern half of the United States to the Atlantic Coast.
Habitat: Common in coniferous woods at moderate to mid-elevationn in the mountains
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Orthocarpus barbatus – Grand Coulee owl-clover
Distribution: Occurring east of the Cascades crest in Washington. southern British Columbia to Washington.
Habitat: Dry, open ground in sagebrush-steppe.
Origin: Native
Flowers: May-June
Growth Duration: Annual
Distribution: Occurring east of the Cascades crest in Washington. southern British Columbia to Washington.
Habitat: Dry, open ground in sagebrush-steppe.
Origin: Native
Flowers: May-June
Growth Duration: Annual
Orthocarpus bracteosus – rosy owl-clover
Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to northern California.
Habitat: Meadows at low elevations.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to northern California.
Habitat: Meadows at low elevations.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Orthocarpus imbricatus – mountain owl-clover
Distribution: Occurring west of the Cascades crest in the Olympic Mountains; British Columbia to Oregon and California.
Habitat: Fairly dry meadows and rocky slopes, mid- to high elevations in the mountains.
Origin: Native
Flowers: July-September
Growth Duration: Annual
Distribution: Occurring west of the Cascades crest in the Olympic Mountains; British Columbia to Oregon and California.
Habitat: Fairly dry meadows and rocky slopes, mid- to high elevations in the mountains.
Origin: Native
Flowers: July-September
Growth Duration: Annual
Orthocarpus luteus – golden-tongue owl-clover
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains, northern Great Plains, and Great Lakes region.
Habitat: Low ground, from the plains to moderate elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Distribution: Occurring east of the Cascades crest in Washington; British Columbia to California, east to the Rocky Mountains, northern Great Plains, and Great Lakes region.
Habitat: Low ground, from the plains to moderate elevations in the mountains.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Orthocarpus tenuifolius – narrow-leaved owl-clover, thin-leaved owl-clover
Distribution: Occurring east of the Cascades crest in Washington; southern British Columbia to central Oregon, east to western Montana.
Habitat: Open, moist or rather dry places, from the valleys and plains to moderate elevtions in the mountains.
Origin: Native
Flowers: May-August
Growth Duration: Annual
Distribution: Occurring east of the Cascades crest in Washington; southern British Columbia to central Oregon, east to western Montana.
Habitat: Open, moist or rather dry places, from the valleys and plains to moderate elevtions in the mountains.
Origin: Native
Flowers: May-August
Growth Duration: Annual
Oryzopsis asperifolia – white-grain mountain ricegrass
Distribution: Occurring east of the Cascades crest in northeastern Washington; Yukon Territory to Washington, east to the Rocky Mountains, Great Plains, Great Lakes region, and northeastern North America.
Habitat: Open coniferous woods.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in northeastern Washington; Yukon Territory to Washington, east to the Rocky Mountains, Great Plains, Great Lakes region, and northeastern North America.
Habitat: Open coniferous woods.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Osmorhiza berteroi – mountain sweet-cicely
Distribution: Occurring on both sides of the Cascades crest in Washington; southern Alaska to California, east to the Rocky Mountains, Great Lakes region, and eastern North America.
Habitat: Forest understory and edge, from near sea level to middle elevations in the mountains.
Origin: Native
Flowers: April-July
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; southern Alaska to California, east to the Rocky Mountains, Great Lakes region, and eastern North America.
Habitat: Forest understory and edge, from near sea level to middle elevations in the mountains.
Origin: Native
Flowers: April-July
Growth Duration: Perennial
Osmorhiza depauperata – blunt-fruit sweet-cicely
Distribution: Occurring chiefly east of the Cascades crest in Washington; Alaska to California, east to the northern Great Plains, Great Lakes region, and northeastern North America.
Habitat: Forest understory and edge, often where moist from low to middle elevations.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring chiefly east of the Cascades crest in Washington; Alaska to California, east to the northern Great Plains, Great Lakes region, and northeastern North America.
Habitat: Forest understory and edge, often where moist from low to middle elevations.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Osmorhiza occidentalis – Sierran sweet-cicely, western sweet-cicely
Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to California, east to the Rocky Mountains from Alberta to Utah.
Habitat: Forest openings and edge, thickets, and riparian zones from low to middle elevations.
Origin: Native
Flowers: April-July
Growth Duration: Perennial
Distribution: Occurring chiefly east of the Cascades crest in Washington; southern British Columbia to California, east to the Rocky Mountains from Alberta to Utah.
Habitat: Forest openings and edge, thickets, and riparian zones from low to middle elevations.
Origin: Native
Flowers: April-July
Growth Duration: Perennial
Osmorhiza purpurea – purple sweet-cicely
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to Alberta, Idaho, and Montana.
Habitat: Moist forest openings, understory, and edge from low to middle elevations in the mountains.
Origin: Native
Flowers: June-July
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to Alberta, Idaho, and Montana.
Habitat: Moist forest openings, understory, and edge from low to middle elevations in the mountains.
Origin: Native
Flowers: June-July
Growth Duration: Perennial
Oxalis corniculata – creeping yellow wood-sorrel
Distribution: Occurring chiefly west of the Cascades crest and along the Columbia River in Washington; British Columbia to California, east across most of North America to the Atlantic Coast;
Habitat: A weed of gardens, disturbed areas, and waste places.
Origin: Introduced from Europe
Flowers: May-October
Growth Duration: Perennial
Distribution: Occurring chiefly west of the Cascades crest and along the Columbia River in Washington; British Columbia to California, east across most of North America to the Atlantic Coast;
Habitat: A weed of gardens, disturbed areas, and waste places.
Origin: Introduced from Europe
Flowers: May-October
Growth Duration: Perennial
Oxalis dillenii – slender yellow wood-sorrel
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to Oregon, east across most of North America to the Atlantic Coast.
Habitat: Open areas, often where moist, at low elevations.
Origin: Introduced from central and eastern North America
Flowers: February-October
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to Oregon, east across most of North America to the Atlantic Coast.
Habitat: Open areas, often where moist, at low elevations.
Origin: Introduced from central and eastern North America
Flowers: February-October
Growth Duration: Perennial
Oxalis oregana – redwood-sorrel, Oregon wood-sorrel
Distribution: Occurring west of the Casades crest in Washington; Olympic Mountains and west slope of the Cascades in Washington; British Columbia south to California.
Habitat: Moist woods, low to moderate elevations.
Origin: Native
Flowers: April-September
Growth Duration: Perennial
Distribution: Occurring west of the Casades crest in Washington; Olympic Mountains and west slope of the Cascades in Washington; British Columbia south to California.
Habitat: Moist woods, low to moderate elevations.
Origin: Native
Flowers: April-September
Growth Duration: Perennial
Oxalis stricta – upright yellow wood-sorrel
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to Washington, Idaho, and Arizona, east across most of North America to the Atlantic Coast.
Habitat: Disturbed ground, lawns and gardens.
Origin: Introduced from central and eastern North America
Flowers: April-September
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to Washington, Idaho, and Arizona, east across most of North America to the Atlantic Coast.
Habitat: Disturbed ground, lawns and gardens.
Origin: Introduced from central and eastern North America
Flowers: April-September
Growth Duration: Perennial
Oxalis suksdorfii – western yellow wood-sorrel
Distribution: Occurring west of the Cascades crest in Washington; southern Washington to northwest California.
Habitat: Low elevations, usually in moist, coastal woods but sometimes on rather dry, open slopes.
Origin: Native
Flowers: April-August
Growth Duration: Perennial
Distribution: Occurring west of the Cascades crest in Washington; southern Washington to northwest California.
Habitat: Low elevations, usually in moist, coastal woods but sometimes on rather dry, open slopes.
Origin: Native
Flowers: April-August
Growth Duration: Perennial
Oxalis trilliifolia – great wood-sorrel, trillium-leaf wood-sorrel
Distribution: Occurring west of the Cascades crest in Washington; Washington to northwest California, disjunct in northern Idaho.
Habitat: Meadows and moist woods in the coastal mountains and up to 6000 feet in the Cascades.
Origin: Native
Flowers: May-August
Growth Duration: Perennial
Distribution: Occurring west of the Cascades crest in Washington; Washington to northwest California, disjunct in northern Idaho.
Habitat: Meadows and moist woods in the coastal mountains and up to 6000 feet in the Cascades.
Origin: Native
Flowers: May-August
Growth Duration: Perennial
Oxybasis chenopodioides – low goosefoot, red goosefoot
Distribution: Occurring east of the Cascades crest in Washington; British Coilumbia to California, east to the Rocky Mountains.
Habitat: Sagebrush desert to sandy areas or mountain slopes, often on roadsides.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Distribution: Occurring east of the Cascades crest in Washington; British Coilumbia to California, east to the Rocky Mountains.
Habitat: Sagebrush desert to sandy areas or mountain slopes, often on roadsides.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Oxybasis glauca – glaucous goosefoot, oakleaf goosefoot
Distribution: Occcurring on both sides of the Cascades crest in Washington; Alaska to California, east across the northern half of North America to the Atlantic Coast; also in Eurasia.
Habitat: Open, sometimes disturbed, areas, often where soil is alkaline or saline.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Distribution: Occcurring on both sides of the Cascades crest in Washington; Alaska to California, east across the northern half of North America to the Atlantic Coast; also in Eurasia.
Habitat: Open, sometimes disturbed, areas, often where soil is alkaline or saline.
Origin: Native
Flowers: June-August
Growth Duration: Annual
• ssp. glauca – oak-leaf goosefoot
• ssp. salina – Rocky Mountain goosefoot
Oxybasis macrosperma – large seed goosefoot
Distribution: Occurring west of the Cascades crest in Washington; southwestern British Columbia to Washington, also in California and North Carolina.
Habitat: Disturbed, moist sites and shorelines.
Origin: Introduced from South America
Flowers: June-August
Growth Duration: Annual
Distribution: Occurring west of the Cascades crest in Washington; southwestern British Columbia to Washington, also in California and North Carolina.
Habitat: Disturbed, moist sites and shorelines.
Origin: Introduced from South America
Flowers: June-August
Growth Duration: Annual
Oxybasis rubra – red goosefoot
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Great Plains, Great Lakes Region, and Atlantic Coast.
Habitat: Moist, saline soils.
Origin: Both native and introduced
Flowers: July-October
Growth Duration: Annual
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Great Plains, Great Lakes Region, and Atlantic Coast.
Habitat: Moist, saline soils.
Origin: Both native and introduced
Flowers: July-October
Growth Duration: Annual
• var. humilis – marshland goosefoot
• var. rubra – red goosefoot
Oxyria digyna – mountain-sorrel
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains; also east across Canada to Labrador.
Habitat: Moist, usually rocky ground, subalpine to alpine areas.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east to the Rocky Mountains; also east across Canada to Labrador.
Habitat: Moist, usually rocky ground, subalpine to alpine areas.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Oxytheca dendroidea – treelike puncture-bract
Distribution: Occurring east of the Cascades crest in Washington; central Washington to California, east to southern Idaho, Wyoming, and Nevada; also in South America.
Habitat: Sandy areas in sagebrush desert.
Origin: Native
Flowers: June-August
Growth Duration: Annual
Distribution: Occurring east of the Cascades crest in Washington; central Washington to California, east to southern Idaho, Wyoming, and Nevada; also in South America.
Habitat: Sandy areas in sagebrush desert.
Origin: Native
Flowers: June-August
Growth Duration: Annual
• ssp. dendroidea – treeline puncturebract
Oxytropis borealis – boreal crazyweed, boreal locoweed
Distribution: Occurring in the Olympic Mountains in Washington; Alaska to California, east to Rocky Mountains, also in eastern Canada.
Habitat: Subalpine and alpine areas.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring in the Olympic Mountains in Washington; Alaska to California, east to Rocky Mountains, also in eastern Canada.
Habitat: Subalpine and alpine areas.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
• var. viscida – sticky boreal crazyweed, sticky boreal locoweed
Oxytropis campestris – field locoweed, yellow locoweed
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to Oregon, east across the northern U.S. and Canada to the Atlantic Coast.
Habitat: Forest openings and rocky balds from sea-level to the alpine.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to Oregon, east across the northern U.S. and Canada to the Atlantic Coast.
Habitat: Forest openings and rocky balds from sea-level to the alpine.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
• var. columbiana – slender crazyweed
• var. cusickii – Cusick's field crazyweed, Cusick's field locoweed
• var. spicata – yellow-flowered crazyweed, yellow-flowered locoweed
• var. wanapum – Wanapum crazyweed, Wanapum locoweed
Oxytropis deflexa – pendent-pod crazyweed, pendent-pod locoweed
Distribution: Occurring east of the Cascades crest in north-central Washington; Alaska to California, east to the Rocky Mountains, and east across Canada to the Atlantic Coast.
Habitat: Montane forest openings and meadows to the subalpine and alpine.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in north-central Washington; Alaska to California, east to the Rocky Mountains, and east across Canada to the Atlantic Coast.
Habitat: Montane forest openings and meadows to the subalpine and alpine.
Origin: Native
Flowers: June-August
Growth Duration: Perennial
• var. sericea – pendent-pod crazyweed, pendent-pod locoweed
Ozomelis diversifolia – angle-leaf bishop's-cap
Distribution: Occurring from in southern Cascade Mountains from Mt. Adams south in Washington; Washington south to the Trinity Mountains of northwest California.
Habitat: Moist woods and stream banks at moderate to high elevations.
Origin: Native
Flowers: May-June
Growth Duration: Perennial
Distribution: Occurring from in southern Cascade Mountains from Mt. Adams south in Washington; Washington south to the Trinity Mountains of northwest California.
Habitat: Moist woods and stream banks at moderate to high elevations.
Origin: Native
Flowers: May-June
Growth Duration: Perennial
Ozomelis stauropetala – cross-shaped mitrewort, side-flowered mitrewort
Distribution: Occurring east of the Cascades crest in Washington; Washington south to Oregon, east to Idaho, Montana, Wyoming, Colorado and Utah.
Habitat: Open to dense moist woods at mid-elevations in the mountains.
Origin: Native
Flowers: May-June
Growth Duration: Perennial
Distribution: Occurring east of the Cascades crest in Washington; Washington south to Oregon, east to Idaho, Montana, Wyoming, Colorado and Utah.
Habitat: Open to dense moist woods at mid-elevations in the mountains.
Origin: Native
Flowers: May-June
Growth Duration: Perennial
Ozomelis trifida – three-toothed mitrewort
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to Alberta, Montana, and Idaho.
Habitat: Moist forests, moderate to mid-elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
Distribution: Occurring on both sides of the Cascades crest in Washington; British Columbia to California, east to Alberta, Montana, and Idaho.
Habitat: Moist forests, moderate to mid-elevations in the mountains.
Origin: Native
Flowers: May-July
Growth Duration: Perennial
