Perennials or subshrubs. Trichomes of leaves 2-rayed, sometimes mixed with 3- or 4-rayed ones. Stems ascending, proximal branches terminating in sterile rosettes, (woody at base), 1.5-8.1 dm. Basal leaves: blade linear to linear-oblanceolate, 3.7-15 cm × 1.5-6(-7) mm, base attenuate, margins usually entire, rarely sparsely denticulate, apex acute. Cauline leaves (distal) sessile; blade similar to basal. Racemes considerably elongated in fruit. Fruiting pedicels ascending, slender, narrower than fruit, (3-) 5-10 mm. Flowers: sepals oblong to linear-oblong, 6-11 mm, lateral pair saccate basally; petals yellow, obovate to suborbicular, (11-)14-20(-22) × (3-)4-11.5 mm, claw 8-13 mm, apex rounded; median filaments 7-11 mm; anthers linear, 2.5-4 mm. Fruits ascending to spreading, narrowly linear, straight or only slightly curved inward, not torulose, (2-)3-8.4(-11) cm × 1.5-2.4(-3.5) mm, 4-angled to only slightly latiseptate, not striped; valves with prominent midvein, pubescent outside, trichomes 2-4-rayed, glabrous inside; ovules 48-82 per ovary; style cylindrical, stout, 0.5-4 mm, sparsely pubescent; stigma slightly 2-lobed, lobes as long as wide. Seeds oblong, 1.5-2.5(-3) × (0.7-)1-1.2(-1.4) mm; not winged or winged apically. 2n = 36.

Flowering Dec-Aug. Stabilized coastal sand dunes, coastal scrub vegetation; 0-150 m; Calif.

Erysimum suffrutescens is restricted to the coastal regions of Los Angeles County northward into San Luis Obispo, Santa Barbara, and Ventura counties. Both G. B. Rossbach (1958, 1958b) and R. C. Rollins (1993) treated it as a distinct species, but R. A. Price (1993) transferred it (invalidly) to a subspecies of E. insulare. The latter species has angustiseptate (versus 4-angled to slightly latiseptate) fruits, and the two are sufficiently distinct to be recognized as independent species.