Tidestrom's Milkvetch

Xylophacos tidestromii Rydb. Bull. Torrey Club
52: 155. 1925.
A perennial, with a deep woody root and short cespitose caudex, subacaulescent; stems
1-5 cm. long, white-woolly; leaves 5-8cm. long, spreading; stipules broadly deltoid, about 5 mm.
long; leaflets 11-15, broadly obovate, 6-12 mm. long and nearly as broad, densely white-silky-
villous on both sides, cuneate at the base, rounded at the apex; peduncles 5-7 cm. long; racemes
2-4 cm. long; bracts lanceolate, 2-4 mm. long; calyx with mixed white and black hairs, the
tube 6-8 mm. long, the teeth subulate, 2 mm. long; corolla unknown, except the keel-petals,
which are 12 mm. long, the blade broadly lunate, with a large auricle, purple-tipped, shorter
than the claw; pod tapering at each end, strongly arched above the middle, strigose-canescent,
cross-reticulate, about 4 cm. long, 4 mm. wide, and nearly 1 cm. thick.
Type locality : Charleston Mountains, Nevada. Distribution: Southern Nevada.

Annual, 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, L eaves 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 5-9, Leaflets 10-many, Leaves hairy on one or both surfaces, Inflorescences racemes, Inflorescence axillary, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals ochroleucous, cream colored, 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 unilocular, Fruit tardily or weak ly dehiscent, Fruit oblong or ellipsoidal, Fruit strongly curved, falcate, bent, or lunate, Fruits winged, carinate, or samaroid, Fruit rugose wrinkled or reticulate, Fruit fleshy, Fruit coriaceous or becoming woody, 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 tidestromii is a species of milkvetch known by the common name Tidestrøm's milkvetch. It is native to the Mojave Desert of California and Nevada, where it grows in limestone gravel soils. The plant is named for the botanist Ivar Frederick Tidestrøm.