Rimrock Milkvetch

Batidophaca petrophila (M. E. Jones) Rydberg, sp. nov
Astragalus desperatus petrophilus M. E. Jones, Rev. Astrag. 204. 1923.
A perennial, with a taproot and a short cespitose caudex; stems 1-4 cm. long, crowded, covered with broad conspicuous stipules and leaf -bases; leaves 1-4 cm. long, ascending; stipules ovate, 2-3 mm. long, pubescent; leaflets 5-9, elliptic to oval, obtuse, 3-4 mm. long, ashystrigose; peduncles 1—3 cm. long; racemes short, 3-5-flowered ; bracts lanceolate, 2—3 mm. long; calyx strigose, the tube 3 mm. long, the teeth lance-subulate, less than 1 mm. long; corolla purple, about 8 mm. long; banner broadly obovate, rather strongly arched above the middle; wings nearly as long, the blade oblong, strongly falcate, with a long reflexed auricle; keel-petals about as long, the blade strongly lunate, obtuse; pod obliquely ovoid, scarcely 1 cm. long, 4-5 mm. wide and thick, white-villous, the upper suture slightly concave, the lower strongly convex, somewhat sulcate at the base, the cross-section broadly subcordate.
Type locality: San Rafael Swell, Utah. Distribution: Type locality and vicinity.

Batidophaca desperata (M. E. Jones) Rydberg
Astragalus desperatus M. E. Jones, Zoe. 2: 243. 1891. Tium desperatum Rydb. Bull. Torrey Club 32: 660. 1906. ^Astragalus naturitensis Payson, Bot. Gaz. 60: 317. 1915.
A cespitose perennial, with a deep woody root; stems numerous, very short; leaves spreading, 3-6 cm. long; stipules imbricate, 4-5 mm. long, ovate, hyaline, hirsute; leaflets 9-13, lance-elliptic to obovate, obtuse, 5-10 mm. long, silky-strigose on both sides; peduncles strict, 3-7 cm. long; bracts broadly elliptic or ovate, hyaline, 3-5 mm. long; flowers reflexed in age; calyx strigose, the tube 5 mm. long, 3 mm. broad, reddish, the teeth triangular, about 2 mm. long; corolla purple, 12-15 mm. long; banner obovate, abruptly arched, striately purple-veined; wings shorter, the blades linear-oblong, falcate; keel-petals shorter, gradually arched, 3 mm. wide, obtuse, dark-purple; pod lunate, acute at each end, more strongly curved towards the apex, hirsute with long hairs, which are pustulate at the base, 1-2.5 cm. long, 3-4 mm. wide, 4—5 mm. thick, acute on the upper suture, more or less sulcate on the lower, sometimes more or less dorso-ventrally compressed, broadly cordate in cross-section.
Type locality: Along Grand River, in eastern Utah.
Distribution: Eastern Utah, western Colorado, and northern Arizona.

Perennial, Herbs, Stems woody below, or from woody crown or caudex, Taproot present, Nodules present, Stems very short, acaulescent or subacaulescent, Stems less than 1 m tall, Stems solid, Stems or young twigs sparsely to densely hairy, Stem hairs hispid to villous, Leaves alternate, Leaves petiolate, Stipules conspicuous, Stipules membranous or chartaceous, Stipules persistent, Stipules free, Stipules clasping stem at the base, Leaves compound, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 5-9, Leaflets 10-many, Leaves hairy on one or both surfaces, Inflorescences racemes, Inflorescence axillary, Bracts very small, absent or caducous, Flowers zygomorphic, Caly x 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 unilocular, Fruit freely dehiscent, Fruit oblong or ellipsoidal, Fruit strongly curved, falcate, bent, or lunate, Fruit exserted from calyx, Fruit beaked, Fruit hairy, Fruit 11-many seeded, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.

Astragalus desperatus (common name - rimrock milkweed) is a perennial plant in the legume family (Fabaceae) found in the Colorado Plateau and Canyonlands region of the southwestern United States.: 120