Description from Flora of China
Erysimum benthamii var. grandiflorum Monnet; Erysimum longisiliquum J. D. Hooker & Thomson (1861), not Schlechtendal (1830-1832); E. szechuanense O. E. Schulz; E. sikkimense Polatschek.
Herbs annual or biennial, (15-)30-80(-100) cm tall. Trichomes 3(or 4)-forked, mixed with fewer malpighiaceous ones. Stems erect, simple or branched basally, often angled, primarily with malpighiaceous trichomes. Basal leaves petiolate, rosulate, withered by flowering. Lower cauline leaves with petioles 1-3(-5) cm; leaf blade narrowly linear to linear-lanceolate, (2-)3-8(-11) cm × (2-)4-10(-14) mm, base attenuate or cuneate, margin coarsely dentate, apex acute or acuminate. Upper cauline leaves sessile or subsessile, denticulate or subentire. Racemes corymbose, densely flowered, bracteate basally, elongated considerably in fruit. Fruiting pedicels divaricate or ascending, (0.5-)0.6-1.5(-2.5) cm, stout, narrower than fruit, straight. Sepals oblong-linear, (5-)6-8 × 1-1.5 mm, lateral pair saccate. Petals orange-yellow to yellow, oblanceolate or spatulate, (0.8-)1-1.5 cm × 2-3(-3.5) mm, apex rounded; claw distinct, subequaling sepals. Filaments yellow, 7-10 mm; anthers linear, 2-3 mm. Ovules 60-90 per ovary. Fruit linear, 4-angled, (6-)7-11(-13) cm × 1.2-1.7 mm, slightly torulose, erect or ascending, straight; valves with a prominent midvein, outside with malpighiaceous and 3- or 4-forked trichomes, inside glabrous; style slender, 1-3 mm, cylindric, narrower than fruit; stigma capitate, subentire. Seeds oblong, 1.5-2 × 0.8-1 mm. Fl. May-Jul, fr. Jul-Sep.
An examination of the syntypes of Erysimum benthamii (including that of var. grandiflorum) and the holotypes of E. longisiliquum and E. szechuanense clearly shows that they are conspecific. Unfortunately, the earliest name for the species, E. longisiliquum, is illegitimate (a later homonym, and the replaced synonym of E. sikkimense). In FRPS, both E. benthamii and E. longisiliquum were recognized, even though they are indistinguishable morphologically. Erysimum benthamii is the earliest legitimate name for the species.
Dry rocky areas, oak woods, open pastures, grassy slopes, meadows, roadsides, mountain slopes; (1900-)2300-4100 m. Sichuan, Xizang, Yunnan [Bhutan, India, Nepal, Sikkim].