Hourglass Peaseed

Sphinctospermum constrictum (S. Wats.) Rose, Contr. U. S. Nat. Herb. 10: 107. 1906.
• Tephrosia constricta S. Wats. Proc. Am. Acad. 24: 46. 1889.
Annual; stem simple or with a few ascending branches, 2-4 dm. high, glabrous or sparingly strigose, slender; leaves sessile, simple, linear, 2-7 cm. long, 1-3 mm. wide, glabrous or nearly so; pedicel 2-5 mm. long, jointed below the middle, recurved; calyx glabrous, the tube about 1 mm. long, the lobes lanceolate, acute, somewhat spread 'rig, 1.5 mm. long: corolla about 5 mm. ong; pod 3-4cm long, 3 mm. wide, glabrous, straight, pendent; seeds fully 2 mm. long, nearly as broad, prismatic, constricted in the middle, the lateral angles with rounded ribs.
Type locality: Guaymas, Sonora,
Distribution: Arizona, Sonora, and Lower California.

Annual, Herbs, Taproot present, Nodules present, Stems erect or ascending, Stems or branches arching, spreading or decumbent, Stems less than 1 m tall, Stems solid, Stems or young twigs glabrous or sparsely glabrate, Stems or young twigs sparsely to densely hairy, Leaves alternate, Leaves petiolate, Stipules inconspicuous, absent, or caducous, Leaves simple, or appearing so, Leaf or leaflet margins entire, Leaflets 1, 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 very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx glabrous, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals pinkish to rose, Banner petal suborbicular, broadly rounded, Wing petals narrow, oblanceolate to oblong, Wing petals auriculate, Wing tips obtuse or rounded, Keel tips obtuse or rounded, not beaked, Keel petals fused on sides or at tip, Stamens 9-10, Stamens or anthers dimorphic, alternating large and small, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Fruit a legume, Fruit unilocular, Fruit freely dehiscent, Fruit elongate, straight, Fruit oblong or ellipsoidal, Fruit exserted from calyx, Fruit internally septate between the seeds, Fruit glabrous or glabrate, Fruit 11-many seeded, Seeds subquadrate, Seed surface smooth, Seeds olive, brown, or black.