Biennials or perennials; (short-lived). Trichomes of leaves 2-4(-7)-rayed. Stems erect, often branched distally, sometimes proximally, (0.5-)1.2-10(-12) dm. Basal leaves (often withered by flowering); blade spatulate to narrowly oblanceolate or linear, 2-18(-27) cm × 3-15(-30) mm, base attenuate, margins entire or dentate to denticulate, apex acute. Cauline leaves (distal) sessile; blade margins entire or denticulate. Racemes considerably elongated in fruit. Fruiting pedicels divaricate to ascending, stout or slender, narrower than fruit, 4-17(-25) mm. Flowers: sepals narrowly oblong, 7-14 mm, lateral pair saccate basally; petals usually orange to yellow, rarely lavender or purplish, suborbicular to obovate, 12-25 (-30) × (5-)6-10(-13) mm, claw 8-16 mm, apex rounded; median filaments 9-18 mm; anthers linear, 3-4 mm. Fruits divaricate or ascending to erect, narrowly linear, straight or curved upward, not torulose, 3.5-11(-15) cm × 1.3-3.3 mm, 4-angled to latiseptate, not striped; valves with prominent midvein, pubescent outside, trichomes 2-5-rayed, glabrous inside; ovules (40-)54-82 per ovary; style cylindrical, usually stout, rarely slender, 0.2-2.5(-3) mm, sparsely pubescent; stigma 2-lobed, lobes as long as wide. Seeds oblong, 1.5-4 × 1-2 mm; winged apically or not winged. 2n = 36.
Martin and Hutchins 1980, Kearney and Peebles 1969, FNA 2010, Allred and Ivey 2012, Heil et al. 2013
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Biennial to short-lived perennial herbs, 10-80 cm tall, from a thick, leaf-covered caudex; stems erect, simple to few-branched; herbage covered with short, appressed hairs. Leaves: Basal leaves often persistent through flowering and fruiting; stem leaves alternate; blades lanceolate, 4-15 cm long, with acute tips and usually dentate or denticulate margins (sometimes entire); pubescence on upper leaf surfaces often stellate. Flowers: Showy and yellow to orange or purple, in dense terminal racemes which elongate considerably in fruit; pedicels ascending in flower and spreading to ascending when in fruit, 4-6 mm long, stout or slender; sepals 4, oblong, 1 cm long, the lateral pair slightly sac-shaped at the base; petals 4 in a cross formation, suborbicular, 12-25 mm long, yellow, orange-yellow, cream-yellow, or lavender (high elevations). Fruits: Capsules linear, 3-15 cm long and 1-3 mm wide, 4-angled, spreading to ascending; seeds oblong, 2 mm long, in one row per locule. Ecology: Found on open slopes, from 3,000-9,500 ft (914-2896 m); flowers March-September. Distribution: Throughout the western US from WA to MT and south to CA, AZ, NM and TX; also in AK and Yukon, CAN; and much of the lower midwest (IA, IL, IN,OH, south to AR and TN. Notes: Erysimum spp. (the wallflowers) are tall, erect, generally unbranched biennials or perennials, with persistent clusters of narrow basal leaves and similar stem leaves; and stems ending in dense clusters of yellow to orange flowers which become long narrow seed pods when mature. E. capitatum is distinguished by its flowers with yellow, orange or purple petals greater than 12 mm long and 5 mm wide; seed pods which are usually upward-pointing; and stems, leaves and seed pods that are covered with short appressed hairs, or occasionally stellate hairs, but are not gray-pubescent. Ethnobotany: Taken as a remedy for tuberculosis; smelled for headache; used as a ceremonial emetic and as an aid in difficult labor; and applied topically for muscle aches. Etymology: Erysimum is from the Greek eryomai, to help or save, referring to the medicinal properties; capitatum means head-like, referring to the dense rounded cluster of flowers at the top of each stem. Editor: SBuckley 2010, AHazelton 2017