STREPTANTHUS Nuttall, J. Acad. Nat. Sci. Philadelphia 5: 143. 1825

Ihsan A. Al-Shehbaz

Tribe: Thelypodieae Prantl in Engler & Prantl, Nat. Pflanzenfam. III. 2: 155. 1891.

Name derivation: Greek streptos, twisted, and anthos, flower, in reference to the crisped petal margin.

Type species: Streptanthus maculatus Nuttall.

Agianthus Greene, Leafl. Bot. Observ. Crit. 1: 228. 1906. Type species: A. bernardinus Greene.   

Cartiera Greene, Leafl. Bot. Observ. Crit. 1: 226. 1906. Type species: C. cordata (Nuttall) Greene (based on Streptanthus cordatus Nuttall).   

Disaccanthus Greene, Leafl. Bot. Observ. Crit. 1: 225. 1906. Type species: D. carinatus (C. Wright) Greene (based on Streptanthus carinatus C. Wright).  

Euclisia Greene, Leafl. Bot. Observ. Crit. 1: 83. 1904. Type species: E. glandulosa (W. J. Hooker) Greene (based on Streptanthus glandulosus W. J. Hooker).

Euklisia Rydberg ex Small, Fl. SE U.S. 486. 1903. Type species: E. hyacinthoides (W. J. Hooker) Small (based on Streptanthus hyacinthoides W. J. Hooker).

Icianthus Greene, Leafl. Bot. Observ. Crit. 1: 197. 1906, nom. superfl. Type species: I. hyacinthoides (W. J. Hooker) Greene  (based on Streptanthus hyacinthoides (W. J. Hooker).

Mesoreanthus Greene, Leafl. Bot. Observ. Crit. 1: 88. 1904. Type species: M. barbiger (Greene) Greene (based on Streptanthus barbiger Greene).  

Microsemia Greene, Leafl. Bot. Observ. Crit. 1: 89. 1904. Type species: M. polygaloides (A. Gray) Greene (based on Streptanthus polygaloides A. Gray).  

Mitophyllum Greene, Leafl. Bot. Observ. Crit. 1: 88. 1904, non O. E. Schulz, Notizbl. Bot. Gart. Berlin-Dahlem 11: 872. 1933.  Type species: M. diversifolium (S. Watson) Greene (based on Streptanthus diversifolius S. Watson).

Pleiocardia Greene, Leafl. Bot. Observ. Crit. 1: 85. 1904. Type species: P. tortuosa (Kellogg) Greene (based on Streptanthus tortuosus Kellogg).

     Herbs, annual, biennial, or short-lived perennial; caudex poorly developed, rarely woody. Trichomes absent or simple. Multicellular glands absent. Stems simple or branched, often glabrous and glaucous above, leafy. Basal leaves petiolate or sessile, rosulate or not, simple, entire or dentate to lyrate-pinnatifid; middle cauline leaves usually auriculate-clasping, rarely petiolate, entire or dentate. Racemes several to many flowered, ebracteate or bracteate basally or rarely throughout, simple or branched, with or without a terminal cluster of sterile flowers, elongated in fruit; rachis straight or flexuous; fruiting pedicels erect to divaricate or rarely reflexed, persistent. Sepals ovate, lanceolate, or rarely suborbicular, free or connivent, erect, caducous, equal or unequal, often brightly colored, forming urceolate or campanulate and actinomorphic or zygomorphic calyx, glabrous or with apical trichomes or callosities, often saccate basally. Petals white, yellow, pink, rose, purple, violet, brownish, or greenish, erect at base, longer or shorter than sepals; blade linear, oblong, obovate, or suborbicular, narrow and crisped or channeled or broad and neither crisped nor channeled, equal or drastically unequal, apex obtuse to rounded; claw poorly differentiated or distinct and narrow, shorter than sepals, glabrous, unappendages, entire; stamens 6, often exserted, erect or recurved, in 3 pairs of unequal length with adaxial pair longest and lateral pair shortes, rarely tetradynamous; filaments wingless, unappendages, glabrous, free or those of median or adaxial pair connate; anthers oblong or linear, not apiculate, sometimes adaxial pair sterile; nectar glands 1, confluent,  subtending bases of all stamens; median nectaries present. Ovules 10-120 per ovary; placentation parietal. Fruits dehiscent capsulare siliques, linear, latiseptate or rarely subterete, not inflated, unsegmented; valves subleathery, with a distinct or obscure midvein, glabrous or rarely pubescent, torulose or smooth, wingless, unappendaged; gynophore obsolete or to 5 mm; replum rounded, visible; septum complete, membranous, veinless; style 0.1–3.5 mm long, cylindric, persistent; stigma entire or 2-lobed, lobes opposite valves, unappendaged. Seeds uniseriate, winged or rarely wingless, oblong to suborbicular, flat or rarely plump; seed coat smooth or minutely reticulate, not mucilaginous when wetted, smooth or minutely reticulate; cotyledons accumbent or rarely obliquely so.

     About 35 species; United States and adjacent northern Mexico.

References: Al-Shehbaz and Mayer (2008), Clifford and Buck (2007), Dolan (1995), Dolan and LaPrè (1989), Hoffman (1952), Howell (1965), Kruckeberg (1957, 1958), Kruckeberg and Morrison (1983) Kruckeberg and Reeves (1995), Kruckeberg et al. (1982), Mayer and Soltis (1994, 1999), Mayer et al. (1994), Morrison (1938), O’Donnell and Dolan (2005), Reeves et al. (1981), Rodman et al. (1981), Rollins (1963).

See interactive key to the species