Annuals; not scapose; pubescent or glabrous, trichomes simple, these mixed with smaller, short-stalked, Y-shaped, forked ones, rarely rays branched. Stems (usually several from base, rarely simple), usually ascending, decumbent, or prostrate, rarely erect, unbranched or branched [basally] distally, (slender). Leaves basal and cauline; petiolate or sessile; basal (withered by fruiting), not rosulate, petiolate, blade margins pinnatifid or pinnatisect; cauline sessile or subsessile, blade margins pinnatifid. Racemes (several-flowered, bracteate throughout), considerably elongated in fruit. Fruiting pedicels erect, ascending, or divaricate, slender. Flowers: sepals erect to ascending, oblong, (glabrous or pubescent); petals yellow, sometimes with purple tinge, oblanceolate, obovate, or spatulate, (slightly longer than sepals), claw undifferentiated from blade; stamens slightly tetradynamous; filaments sometimes slightly dilated basally; anthers ovate, (apex obtuse); nectar glands confluent, subtending bases of stamens. Fruits siliques or silicles, sessile, linear, oblong, or obdeltoid, smooth, strongly angustiseptate; valves [(2 or) 4 in T. capparideum, keeled], not veined, (thin-leathery throughout, or distally subwoody or thick-leathery and tuberculate-rugose), pubescent; replum rounded; septum complete or absent; ovules 4–70 per ovary; style distinct, (slender); stigma capitate. Seeds uniseriate or (in 4-valved fruits) 4-seriate, not winged, oblong; seed coat (reticulate), mucilaginous when wetted; cotyledons incumbent. x = 8.

Distribution

Calif., c Mexico, South America (c Chile).

Discussion

Species 4 (3 in the flora).

Tropidocarpum lanatum (Barnéoud) Al-Shehbaz & R. A. Price is known from central Chile.

Selected References

Robinson, B. L. 1896. The fruit of Tropidocarpum. Erythea 4: 108–119.

Shehbaz, I. A. and R. A. Price. 2001. The Chilean Agallis and Californian Tropidocarpum (Brassicaceae) are congeneric. Novon 11: 292–293.

Shehbaz, I. A. 2003c. A synopsis of Tropidocarpum (Brassicaceae). Novon 13: 392–395.

Lower Taxa

Tropidocarpum californicum, Tropidocarpum capparideum, Tropidocarpum gracile

Key

1	Fruits obdeltoid, valves thick-leathery and tuberculate-rugose distally, puberulent, trichomes antrorse; ovules 4-8 per ovary.	Tropidocarpum californicum
1	Fruits linear or oblong, valves thin-leathery and smooth distally, usually pubescent or puberulent, rarely glabrescent, trichomes retrorse; ovules 25-70 per ovary	> 2
2	Fruits narrowly linear, (25-)30-60(-70) × 1.5-2(-3) mm, length 13-46 times width; valves 2.	Tropidocarpum gracile
2	Fruits oblong, (5-)9-20 × (3-)4-5 mm, length (1.6-)2.8-5 times width; valves (2 or) 4.	Tropidocarpum capparideum