52. Descurainia Webb & Berthelot, Hist. Nat. Îsles Canaries. 3(2,3): 72. 1836.
Tansy mustard [For François Descurain, 1658-1740, French botanist and apothecary]
Barbara E. Goodson, Ihsan A. Al-Shehbaz
Huguenenia Reichenbach, name rejected; Sophia Adanson, name rejected
Annuals, biennials, or perennials [shrubs, subshrubs]; not scapose; glabrous, glabrate, or sparsely to densely pubescent, trichomes usually short-stalked, dendritic, rarely also simple, sometimes mixed with unicellular, glandular, clavate papillae. Stems erect or prostrate, unbranched or branched basally and/or distally. Leaves basal and cauline; petiolate or sessile; basal (often withered by flowering), rosulate, petiolate, blade (1-3-pinnate), margins entire or toothed; cauline petiolate or sessile, blade often similar to basal. Racemes (proximally sometimes bracteate), elongated or not in fruit. Fruiting pedicels divaricate or erect, slender. Flowers: sepals erect to spreading, ovate to oblong or linear; petals usually obovate or oblanceolate, rarely oblong, (shorter to longer than sepals), claw obsolete or distinct, (apex obtuse); stamens tetradynamous; filaments not dilated basally; anthers oblong to ovate, (apex obtuse); nectar glands confluent, subtending bases of stamens, median glands present. Fruits siliques or silicles, sessile, usually linear, oblong, clavate, or fusiform, rarely ellipsoid or obovoid, smooth or torulose, terete; valves each often with distinct midvein, usually glabrous, rarely pubescent; replum rounded; septum complete or perforated (membranous, not veined or with 1-3 longitudinal veins); ovules 5-100 per ovary; style usually absent, rarely distinct; stigma capitate. Seeds uniseriate or biseriate, plump, wingless, oblong or ellipsoid; seed coat (minutely reticulate), usually mucilaginous when wetted; cotyledons incumbent. x = 7.
Species 45-47 (14 in the flora): North America, Mexico, South America, Eurasia, n Africa, Atlantic Islands (Canary Islands).
SELECTED REFERENCES Bramwell, D. 1977. A revision of Descurainia Webb & Berth. section Sisymbriodendron (Christ) O. E. Schulz in the Canary Islands. Bot. Macar. 4: 31-53. Detling, L. E. 1939. A revision of the North American species of Descurainia. Amer. Midl. Naturalist 22: 481-520. Goodson, B. E. 2007. Molecular Systematics and Biogeography of Descurainia Webb & Berthel. (Brassicaceae). Ph.D. dissertation. University of Texas.