Twinleaf Senna

Earleocassia bauhinioides (A. Gray) Britton
Cassia bauhinioides A. Gray, Bost. Journ. Nat. Hist. 6: 180. 1850.
Herbaceous, more or less branched at base, somewhat spreading, softly short-pubescent, 1-3 dm. high. Stipules linear, persistent, 3-6 mm. long; leaflets I pair, oblong, 1-4.5 cm. long, obtuse, or rounded, softly pubescent on both sides; gland between the leaflets narrow, elongated; peduncles 1-2-flowered; sepals thin, oblong, pubescent, 6-8 mm. long; petals 18 mm. long or shorter; ovary densely pubescent; style glabrous; legume compressed, curved, 2-3.2 cm. long, 5-7 mm. wide, long-pubescent, obliquely short-tipped.
Type locality: On the Rio Grande, Texas.
Distribution: Texas, New Mexico, and Arizona to Zacatecas and Hidalgo.

Perennial, Shrubs, Herbs, Woody throughout, Stems woody below, or from woody crown or caudex, Taproot present, Stems erect or ascending, Stems or branches arching, spreading or decumbent, Stems less than 1 m tall, Stems solid, Stems or young twigs sparsely to densely hairy, Leaves alternate, Leaves petiolate, Extrafloral nectary glands on petiole, Stipules inconspi cuous, absent, or caducous, Stipules conspicuous, Stipules setiform, subulate or acicular, Stipules persistent, Stipules free, Leaves compound, Leaves even pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 2, Leaves glabrous or nearly so, Flowers solitary in axils, or appearing solitary, Flowers in axillary clusters or few-floweredracemes, 2-6 flowers, Inflorescence axillary, Bracts conspicuously present, Bracts very small, absent or caducous, Flowers actinomorphic or somewhat irregular, Calyx 5-lobed, Calyx glabrous, Petals separate, Petals orange or yellow, Fertile stamens 6-8, Stamens heteromorphic, graded in size, Stamens completely free, separate, Filaments glabrous, Anthers opening by basal or terminal pores or slits, Style terete, Fruit a legume, Fruit stipitate, Fruit unilocular, Fruit freely dehiscent, Fruit elongate, straight, Fruit oblong or ellipsoidal, Fruit exserted from calyx, Fruit compressed between seeds, Fruit hairy, Fruit 11-many seeded , Seed with elliptical line or depression, pleurogram, Seeds ovoid to rounded in outline, Seed surface smooth, Seeds olive, brown, or black.

Senna bauhinioides, the twinleaf senna, is a species of flowering plant in the family Fabaceae. It is native to the US states of Arizona, New Mexico, and Texas, and to northern Mexico, and it has been introduced to the US state of Maryland. An opportunistic species, it is unpalatable to livestock, so its presence is considered an indicator of overgrazing.