Arnica chamissonis Leafy Arnica Perennial, 20-100 cm tall, stems single, soft-wavy-hairy. Moist meadows.
Flowerheads yellow, 3-5 cm across, with 10-16 rays. Bracts hair-tipped.
Leaves opposite, lance-shaped, hairy, in 5-10 pairs, clasping stem, short-hairy.
Grindelia squarrosa Curly-cup Gumweed Aromatic plant, 20-60 cm tall, hairless, with many branches. Dry, open places.
Flowerheads yellow, 2-3 cm wide, with sticky, backward curling involucral bracts.
Leaves alternate, oblong, 10-35 mm long, 6-12 mm wide, with resinous glands.
Helianthus annuus Common Sunflower Coarse annual, 40-200 cm tall. Open, dry or moderately moist areas, roadsides.
Flowerheads several, large with yellow rays around a large button of disc florets.
Leaves alternate, egg- to heart-shaped with rough hairs and long stalks.
Lactuca serriola Prickly Lettuce Stem 30-150 cm tall, hairless, branching at sharp angles. Weed, disturbed areas.
Flowerheads 10-15 mm wide, with 13 to 27 ray florets, in open clusters.
Leaves alternate, pinnately lobed, prickly on the midrib beneath and on edges.
Ratibida columnifera Prairie Coneflower Stems 30-120 cm tall, usually several from base. Prairies, disturbed ground.
Flowerheads with 3-7 rays, the disc cluster raised to a tall, cylindrical column.
Leaves alternate, lance-shaped, deeply pinnately cut into 5-9 segments.
Senecio triangularis Arrow-leaved Groundsel Stems stout, erect, unbranched, leafy, 30-150 cm tall. Moist places, mountains.
Flowerheads in a short cluster, with about 8 yellow rays 7-13 mm long.
Leaves alternate, elongate-triangular, stalked, sharp-toothed, nearly hairless.
Solidago gigantea Giant Goldenrod Plant robust, leafy, 30-150 cm tall. Moist, open to shaded places in the valleys.
Flowerheads yellow, with 10-17 rays, 1-3 mm long, in dense pyramidal clusters.
Leaves alternate, crowded, lance-shaped, usually sharply toothed, stalkless.
Tanacetum vulgare Common Tansy Aromatic, branched, 40-150 cm tall, often in dense patches. Disturbed areas.
Flowerheads yellow, 5-10 mm wide, with disc florets only, in large clusters.
Leaves alternate, numerous, fern-like, twice pinnately cut into fine segments.
Tragopogon pratensis Meadow Salsify 15-80 cm tall, hairless, not thickened below the flowerhead. Open places.
Flowerheads yellow, 2-3 cm wide. Bracts narrow, not extending past the rays.
Leaves alternate, grass-like, linear, clasping stem, curved back at tips.
BERBERIDACEAE BARBERRY FAMILY:
Mahonia repens Oregon Grape Trailing shrub 10-30 cm tall, stiff-branched. Lower foothills to forested slopes.
Flowers yellow, about 1 cm wide, with 6 petals and inner and outer sepals.
Leaves alternate, pinnate, the 5-7 leaflets with spine-tipped teeth.
BORAGINACEAE BORAGE FAMILY:
Lithospermum incisum Narrow-leaved Gromwell Stems 5-30 cm tall, with flat, stiff, short hairs. Flowers bright yellow, 15-30 mm long, 1-1.5 cm wide, lobes with ragged edges. Leaves mostly on upper stem, 2-6 cm long and 2-6 mm wide. Dry, open plains and foothills.
BRASSICACEAE MUSTARD FAMILY:
Alyssum alyssoides Pale Madwort 10-30 cm tall, grayish, with flat, star-shaped hairs. Flowers pale yellow, c. 3 mm wide. Sepals persistent on pods. Leaves narrowly oblanceolate, 5-25 mm long. Pods flat-hairy. Dry areas.
Descurainia pinnata Western Tansymustard Annual, 10-70 cm tall, green or grayish-short-hairy. Flowers yellow, ca 5 mm wide, petals slightly longer than sepals. Leaves once pinnate with linear segments. Plains, hills.
Descurainia sophia Common Tansymustard Annual, 30-100 cm tall, often gray-short-hairy. Flowers yellow, ca 2 mm long, petals slightly shorter than sepals. Leaves at least twice pinnate with narrow segments. Plains, hills.
Draba oligosperma Few-seeded Draba Tufted perennial, stems many, 1-10 cm tall. Flowers yellow, 5-7 mm wide, in dense clusters. Leaves basal, tufted, 3-12 mm long and ca 1 mm broad, branched-hairy. Rocky ridges.
Lepidium perfoliatum Clasping Peppergrass Flowers yellow, very small, in dense, tall clusters. Lower leaves pinnate with narrow segments. Upper leaves entire. Fruit pods obovate, short, flattened, about 2-3.5 mm long.
Sinapis arvensis Charlock Mustard Annual, branching and leafy, flowers yellow, 15-20 mm wide. Leaves basal and alternate, with large ending leaflet. Fruit pods linear, 4-5 cm long, quite thick, lined, with long beak.
Sisymbrium altissimum Tall Tumble-mustard 30-150 cm tall, hairless to stiff-hairy below. Flowers pale yellow, 1 cm wide, on branches. Petals narrow. Leaves alternate, pinnately cut into narrow segments. Disturbed ground.
Sisymbrium loeselii Small Tumble-mustard Erect, 40-120 cm tall, mostly long-stiff-hairy. Flowers yellow, ca 1 cm wide, the petals broad. Leaves basal and alternate, pinnately lobed, with larger end lobe. Disturbed ground.
CACTACEAE CACTUS FAMILY:
Escobaria missouriensis Yellow Pincushion Cactus Stems usually spherical, up to 5 cm tall. Valleys, hills and dry grasslands.
Flowers pale yellow, about 2.5 cm long, with many pointed petals.
Spines white, flat to spreading, in many clusters of several spines each.
Opuntia polyacantha Plains Prickly-pear Cactus Stems 10-30 cm tall, composed of several flat, oval sections. Dry hills.
Flowers yellowish to reddish, about 5-7 cm wide, with many broad petals.
Spines in many groups of 5-11, straight, 1-5 cm long, slightly barbed or not.
CLUSIACEAE ST. JOHN'S-WORT FAMILY:
Hypericum scouleri St. Johnswort Stems 10-80 cm tall. Moist, open slopes and ledges, foothills to alpine.
Flowers bright yellow, 2 cm wide, petals edged with small black dots or teeth.
Leaves opposite, broadly egg-shaped, 1-3 cm long, black-dotted along edges.
CRASSULACEAE STONECROP FAMILY:
Sedum lanceolatum Lance-leaved Stonecrop Succulent herb, 5-20 cm tall. Dry, stony, open sites and rock outcrops.
Flowers yellow, 1-1.5 cm wide, with 5 petals, in dense, flat-topped clusters.
Leaves alternate, narrowly lance-shaped, about 1 cm long, fleshy, rounded.
EUPHORBIACEAE SPURGE FAMILY:
Euphorbia esula Leafy Spurge Herb with milky juice, 20-90 cm tall. Weed on disturbed ground.
Flowers greenish-yellow, lacking petals and sepals, in umbrella-shaped clusters.
Leaves alternate, 2-6 cm long, linear, numerous, stalkless.
Euphorbia robusta Rocky Mountain Spurge Herb with milky juice, 10-30 cm tall. Dry areas, foothills and lower mountains.
Flowers greenish-yellow, lacking petals and sepals, in umbrella-shaped clusters.
Leaves alternate to opposite, 1-2 cm long, ovate, pointed, numerous, stalkless.
FABACEAE PEA FAMILY:
Caragana arborescens Siberian Pea-shrub Deciduous large shrub to small tree, up to 5 m tall. Roadsides, cultivated.
Flowers yellow, about 2 cm long, 1 to 4 in bundles from leaf axils, long-stalked.
Leaves pinnately compound with 8 to 12 leaflets in pairs, without end leaflet.
Lotus corniculatus Birdfoot Deer-vetch Stems trailing to ascending, 10-40 cm tall. Bottomlands or wet places.
Flowers yellow, 8-15 mm long, about 3-15 in long-stalked, head-like umbels.
Leaves with 5 leaflets, the lowest pair basal, the other 3 on a short stalk.
Medicago lupulina Black Medic Creeping to ascending annual or biennial, found mostly on disturbed ground.
Flowers yellow, 2-3 mm long, growing in small, round clusters, 5-10 mm long.
Leaves are divided into 3 leaflets, elliptic to round, with sharp point at tips.
Medicago sativa Alfalfa Plant 30-100 cm tall. Introduced, mostly on disturbed ground, used for forage.
Flowers blue to whitish-yellow, 7-11 mm long, in rounded, stalked clusters.
Leaves are divided into 3 leaflets which are sharply toothed on upper halves.
Melilotus officinalis Yellow Sweet-clover Annual or biennial, 50-300 cm tall, freely branched. Mostly disturbed ground.
Flowers 4-6 mm long, yellow, sweet-smelling, in slender, spike-like clusters.
Leaves with 3 leaflets, elliptic to oblong, sharply toothed, the middle one stalked.
GROSSULARIACEAE CURRANT FAMILY:
Ribes aureum Golden Currant Shrub 1-3 m tall, without spines. Stream banks, flood plains to forests.
Flowers yellow, about 10-15 mm long, with 5 spreading lobes and long tube.
Leaves 2-5 cm broad, mostly 3-lobed, hairless. Berries black, about 7 mm long.
LILIACEAE LILY FAMILY:
Erythronium grandiflorum Glacier Lily Stems 10-40 cm tall, leafless. Moist sites, forest openings, montane to alpine.
Flowers bright yellow, solitary, nodding, 3-6 cm wide, 6 tepals curved upwards.
Leaves basal in 1 pair, bright green, lance-shaped to elliptic.
Fritillaria pudica Yellowbells Stems 10-30 cm tall, often clustered. Grasslands and sagebrush areas.
Flowers yellow, nodding, usually solitary, about 2 cm long, narrowly bell-shaped.
Leaves basal, 2 and usually almost opposite. Bulbs and seed pods edible.
LOASACEAE EVENINGSTAR FAMILY:
Mentzelia laevicaulis Smooth-stemmed Eveningstar Biennial, 30-100 cm tall, branched, with short, barbed hairs. Dry, open sites.
Flowers lemon-yellow, 5-15 cm across, with 5 petals, open at daytime.
Leaves alternate, oblanceolate, 4-15 cm long, pinnatifid with wavy lobes.
MALVACEAE MALLOW FAMILY:
Sphaeralcea coccinea Scarlet Globemallow Low, spreading plant, 10-20 cm tall, gray-hairy. Dry, open sites, plains-montane.
Flowers orange, about 2 cm wide, short-stalked, in small clusters.
Leaves alternate, deeply cut into 3-5 palmate, wedge-shaped segments.
ONAGRACEAE EVENING PRIMROSE FAMILY:
Oenothera villosa Hairy Evening Primrose Robust biennial with hairy stems, 30-100 cm tall. Dry, moderately open sites.
Flowers fragrant, bright yellow, 3-4 cm wide, in a tall cluster, with 4 broad petals.
Leaves alternate and basal, lance-shaped, numerous, entire to wavy-toothed.
PRIMULACEAE PRIMROSE FAMILY:
Lysimachia ciliata Fringed Loosestrife Stems single, leafy, 30-120 cm tall. Damp meadows, ponds, along streams.
Flowers yellow, about 2 cm wide, with 5 spreading round lobes, point-tipped.
Leaves opposite, ovate, 5-15 cm long, rough-edged, the stalks 5-20 mm long.
RANUNCULACEAE BUTTERCUP FAMILY:
Aquilegia flavescens Yellow Columbine Plants usually 20-70 cm tall, freely branched. Open sites, foothills to alpine.
Flowers lemon-yellow, about 5 cm wide, nodding. Petals with a long spur.
Leaves mainly basal, divided in 3's, long-stalked. Leaflets mostly round.
Ranunculus eschscholtzii Mountain Buttercup Alpine plant, hairless, 5-20 cm tall. Meadows and rocky slopes.
Flowers 10-20 mm wide, 1-3 on long stalks. Sepals brown-hairy.
Leaves basal, kidney-shaped, with 3-5 main, lobed segments.
Ranunculus flammula Spearwort Buttercup Creeping plant, 5-10 cm tall. Shores, plains-subalpine.
Flowers 5-10 mm wide, solitary, on erect stalks.
Leaves basal, linear to lance-shaped, 1-5 cm long, 1-7 mm wide.
Geum macrophyllum Large-leaved Avens Stems 30-70 cm tall, spreading-stiff-hairy. Moist woods or meadowland.
Flowers yellow, 15-20 mm wide, with 5 rounded petals. Sepals bent back.
Leaves pinnately divided into 5-9 main leaflets, the final leaflet much larger.
Pentaphylloides floribunda Shrubby Cinquefoil Spreading shrub with wooden stems. Rocky areas, plains-subalpine.
Flowers yellow, regular, clustered on branches. Petals 5, round, 8-13 mm long.
Leaves small, crowded on stems, divided into 5-7 narrow segments.
Potentilla argentea Silver Cinquefoil Stems short-grayish-woolly, 15-30 cm tall. Dry areas.
Flowers c. 15 mm wide. Sepals flat-hairy, petals not touching.
Leaves gray-woolly beneath, the 5 leaflets toothed, 1-2 cm long.
Potentilla recta Sulphur Cinquefoil Plant 30-80 cm tall, very leafy, branched on upper parts. Weed.
Flowers pale yellow. Petals heart-shaped, 9-12 mm long.
Leaves several on stems, divided into 5-7 leaflets, saw-toothed.
SCROPHULARIACEAE FIGWORT FAMILY:
Castilleja nivea Snow Indian Paintbrush Stems 5-15 cm tall, with short, woolly hairs. Montane to alpine zones.
Flowers yellow, woolly-hairy. Bracts are hairy, divided into 3 lobes.
Leaves linear, mostly with 2 side-lobes, with short, woolly hairs.
Linaria dalmatica Dalmatian Toadflax Plant trailing to erect, branching. Disturbed ground at low elevations.
Flowers yellow with orange on lower lip, in open clusters from branches.
Leaves alternate, numerous, broadly lance-shaped, with bluish cast.
Linaria vulgaris Common Toadflax Plant 20-80 cm tall, erect, unbranched. Disturbed ground, plains to montane.
Flowers yellow with orange on lower lip, in tall, slender clusters.
Leaves alternate, numerous, linear, with bluish cast.
Mimulus guttatus Yellow Monkeyflower Stems erect or trailing, branched, 10-50 cm tall. Wet sites, foothills to subalpine.
Flowers large, yellow, red-spotted, several in loose clusters. Lower lip large.
Leaves egg-shaped. Lower leaves larger, often with ragged lobes at bases.
Orthocarpus luteus Yellow Owl-clover Stems slender, 10-40 cm tall, glandular-hairy. Dry, open sites, plains-montane.
Flowers yellow, tubular, 9-14 mm long, wider near tip. Bracts are 3-5-lobed.
Leaves alternate, linear, 1.5-4 cm long, stalkless, rough-hairy.
Verbascum thapsus Great Mullein Stout plants, 40-200 cm tall. Disturbed ground, plains to subalpine.
Flowers yellow, 1-2 cm wide, with 5 equal lobes, numerous in tall, dense spikes.
Leaves basal and alternate, broadly lance-shaped, 10-40 cm long, stalkless.
SOLANACEAE NIGHTSHADE FAMILY:
Hyoscyamus niger Henbane Coarse plant, up to 100 cm tall. Introduced weed, poisonous, disturbed ground.
Flowers yellowish, 2-3 cm wide, with 5 round lobes from a urn-shaped calyx.
Leaves alternate, egg-shaped and cut into triangular, pointed lobes.
VIOLACEAE VIOLET FAMILY:
Viola vallicola Valley Violet Perennial up to 15 cm tall. Sagebrush and wooded areas, plains to mountains.
Flowers yellow, 8-15 mm long, from the base. Upper 2 petals brownish on back.
Leaves basal, the stalks 3-15 cm long, the blades ovate, 2-5 cm long.