Brazos Milkvetch

Hesperastragalus brazoensis (Buckl.) Rydb. Bull. Torrey
Club 53: 166. 1926.
Astragalus brazoensis Buckl. Proc. Acad. Phila. 1861: 452. 1862. Tragacantha brazoensis Kuntze, Rev. Gen. 943. 1891.
An annual; stem branched at the base, erect, or decumbent at the base, 1-4 dm. high, sparingly strigose, striate; leaves ascending, 3-6 cm. long, the rachis sparingly strigose; stipules deltoid 3 mm. long; leaflets 13-15, cuneate or oblong-obovate, retuse at the apex, 5-10 mm. long glabrous above, sparingly strigose beneath, often only on the margins and midribs; peduncles 5-8 cm. long, ascending; racemes 1-4 cm. long; bracts lance-subulate, 1-2 mm. longcalyx sparingly strigose, the tube campanulate, 1.5 mm. long, the teeth subulate, 2 mm. long' corolla purplish or white, with purple-tipped keel; banner broadly obovate, slightly retuse abruptly arcuate at the middle; wings shorter, the blade obliquely oblong-oblanceolate, falcatekeel-petals slightly shorter, the blade semi-orbicular, obtuse at the tip; pod distinctly stipitate, cross-reticulate, 5-7 mm. long and as thick, 4 mm. wide, deeply sulcate on the lower suture, the dorsi-ventral view suborbicular, subcordate at the base and abruptly beaked at the apex; seeds 2 or 3 in each cavity.
Type locality: Western Texas.
Distribution: Texas and Tamaulipas.

Annual, Herbs, Taproot present, Nodules present, Stems erect or ascending, Stems less than 1 m tall, Stems solid, Stems or young twigs glabrous or sparsely glabrate, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules membranous or chartaceous, Stipules persistent, Stipules free, Leaves compound , Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 10-many, Leaves hairy on one or both surfaces, Inflorescences racemes, Inflorescences globose heads, capitate or subcapitate, Inflorescence axillary, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx glabrous, Petals separate, Corolla papilionaceous, Petals clawed, Petals blue, lavander to purple, or violet, Petals bicolored or with red, purple or yellow streaks or spots, Banner petal narrow or oblanceolate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel petals auriculate, spurred, or gibbous, Keel tips obtuse or rounded, not beaked, Stamens 9-10, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style persistent in fruit, Fruit a legume, Fruit stipitate, Fruit freely dehiscent, Fruit oblong or ellipsoidal, Fruit rugose wrinkled or reticulate, Fruit coriaceous or becoming woody, Fruit exserted from calyx, Fruit beaked, Fruit glabrous or glabrate, Fruit 3-10 seeded, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.