Perennials. Stems simple or few from caudex, erect, (often much-branched distally), (2.5-)3.5-10(-15) dm. Leaves shortly petiolate; blade usually linear to linear-lanceolate, rarely lanceolate, (2.5-)3.5-12(-15) cm × (1-)2-6(-10) mm (smaller distally), base cuneate to attenuate (or petiolelike), margins entire or, very rarely, sparsely denticulate, apex acuminate to acute. Racemes several-flowered, (proximalmost flowers sometimes bracteate). Fruiting pedicels divaricate or ascending, straight, (5-)8-20(-25) mm. Flowers: sepals purplish, (4-)4.5-7 × 1-2 mm, (median pair apical cuculla to 0.7 mm); petals purple, (10-)12-16(-18) × (2-)3.5-5.5 mm, claw distinctly differentiated from blade, [5-7(-9) mm]; filaments 2-4 mm; anthers narrowly oblong to linear, 2-4 mm; gynophore 0.4-1(-2) mm. Fruits usually straight, rarely curved, terete, (3.5-)4-9(-11) cm × 1-1.5 mm; ovules (76-)80-110 per ovary; style subclavate to cylindrical, 0.5-1.8(-2.5) mm; stigma conical, 2-lobed (lobes prominent, connivent). Seeds 0.9-1.6 × 0.5-0.9 mm. 2n = 22, 44. Flowering Jul-Nov. Open woods, dry hillsides, oak woodland, mixed conifer forests, arroyos, canyons, rocky ridges, limestone ledges, sandstone crevices, roadsides; 700-3100 m; Ariz., Colo., N.Mex., Tex.; Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Zacatecas).
Martin and Hutchins 1980, Kearney and Peebles 1969, Heil et al. 2013
Duration: Perennial Nativity: Native Lifeform: Subshrub General: Perennial herb, 30-100 cm tall, from a branched woody caudex; stems 1-several, slender and erect, simple or branched, the branches pointing upward; herbage glabrous. Leaves: First-year plants have a basal rosette of leaves which are petiolate, oblanceolate, 5-10 cm long, entire to toothed, and early-deciduous; stem leaves are oblanceolate low on the stem and linear above, short-petiolate or with cuneate bases, mostly entire or slightly toothed around the edges. Flowers: Purple and somewhat showy, in few-flowered racemes at branch tips, with ascending pedicels to 1 cm long; sepals 4, purplish, 5-6 mm long, the inner pair with slightly sac-shaped bases; petals 4, forming an X-shape, each petal 1-2 cm long, lavender to purplish with darker veins, with an obovate blade and slender claw. Fruits: Capsules linear, very slender, 3 mm to 7 cm long, ascending; seeds 1.5 mm long, in one row per locule. Ecology: Found in dry soils, widespread, from 4,500-9,500 ft (1372-2896 m); flowers May-September. Distribution: AZ, s CO, NM, sw TX; south to n MEX. Notes: A distinct mustard due to its often large size( to 1 m) and its erect, photosynthetic, green stems which can have many to sparse leaves or are leafless, at least on the lower stem; the short-petioled, entire, linear leaves, and inflorescences of showy flowers with purple (occasionally white), spoon-shaped petals followed by very thin, linear, ascending fruits. Ethnobotany: Used as a ceremonial eyewash and as a mouthwash for sore gums. Etymology: Hesperidanthus refers to Hesperis, another genus in the mustard family, plus -anthos, flower, meaning that the showy purple flower resembles that of Hesperis; linearifolius means linear leaves. Synonyms: Schoenocrambe linearifolia, Sisymbrium linearifolium, Thelypodiopsis linearifolia Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017