Pennellia

Perennials; not scapose; pubescent or glabrous, trichomes simple, with stalked, forked or dendritic ones. Stems erect [ascending], often branched distally. Leaves basal and cauline; petiolate or sessile; basal (withered with age), rosulate, petiolate, blade margins entire, dentate to sinuate, or runcinate; cauline subsessile or sessile [shortly petiolate], blade margins entire [dentate to sinuate]. Racemes (several-flowered, sometimes secund, lax), considerably elongated in fruit. Fruiting pedicels erect, descending, ascending, or divaricate-ascending, slender, (glabrous). Flowers (usually actinomorphic, rarely zygomorphic, cup-shaped); sepals erect, oblong to ovate, lateral pair slightly to strongly saccate basally, (usually pubescent, rarely glabrous); petals white (lavender or purple apically), spatulate to oblanceolate, (± longer than sepals), claw undifferentiated from blade, (apex obtuse); stamens slightly tetradynamous; filaments dilated basally; anthers ovate to oblong, (apex obtuse); nectar glands confluent, subtending bases of stamens. Fruits siliques, sessile or shortly stipitate, linear, not torulose, straight or curved, terete or latiseptate; valves each with prominent or obscure midvein, glabrous or pubescent; replum rounded; septum complete; ovules 40–250 per ovary; style distinct or obsolete; stigma capitate. Seeds uniseriate or biseriate, plump or flattened, winged or not, oblong to ovate; seed coat (reticulate-areolate), mucilaginous or not when wetted; cotyledons accumbent or incumbent. x = 8.

Distribution

sw United States, Mexico, Central America, South America.

Discussion

Species 8 (3 in the flora).

Selected References

Fuentes-Soriano, S. 2004. A taxonomic revision of Pennellia (Brassicaceae). Harvard Pap. Bot. 8: 173–202.

Rollins, R. C. 1980b. The genus Pennellia (Cruciferae) in North America. Contr. Gray Herb. 210: 5–21.

Lower Taxa

Pennellia longifolia, Pennellia micrantha, Pennellia tricornuta

Key

1	Fruits strongly latiseptate, 2-2.5 mm wide; seeds 2.4-2.8 mm, winged (broadly); septums opaque; ovules 40-50 per ovary; cotyledons accumbent.	Pennellia tricornuta
1	Fruits terete or slightly latiseptate, 0.6-1.8 mm wide; seeds 0.7-1.3 mm, not winged; septums transparent; ovules 90-250 per ovary; cotyledons incumbent	> 2
2	Racemes not secund; fruiting pedicels straight, erect or ascending; fruits (1.5-)2.2-5.8 cm, terete; ovules 90-140 per ovary; sepals 2.7-4 mm; petals 1.5-4(-5) mm.	Pennellia micrantha
2	Racemes secund; fruiting pedicels arcuate, reflexed; fruits 5-10 cm, latiseptate; ovules 150-250 per ovary; sepals 4-9 mm; petals (4-)5-7(-12) mm.	Pennellia longifolia