Gravel Milkvetch

Phaca arenicola Rydberg, sp. nov
Perennial; stem somewhat woody at the base, silky-canescent, the branches decumbent below; leaves 5-8 cm. long, the raehis canescent; stipules deltoid, acuminate, distinct, 3-5 mm. long; leaflets 9-13, obovate, rounded to refuse at the apex, 5-10 mm. long, 3-5 mm. wide, appressed silky-canescent; peduncles 3-5 cm. long; racemes 2-3 cm. long, 3-10-flowered; calyx silky-canescent, the tube 2-2.5 mm. long, the lobes lance-subulate, 2.5-3 mm. long; corolla about 6 mm. long, apparently white, streaked with purple; banner broadly obovate; wings somewhat shorter, the blade broadly obliquely obovate, with a large basal aur'cle; keel-petals similar, strongly arcuate, obtuse at the apex; pod (not mature) sessile, hirsute, more than 1 cm. long, the lower suture gibbous, the upper acute and somewhat upcuived.
Type collected in sand at Mecca, Salton Basin, Southern California, Feb. 28, 1913, Parish 8467 (herb. N. Y. Bot. Gard.).

Phaca sabulonum (A. Gray) Rydb. Bull. Torrey Club 40:47. 1913.
Astragalus sabulonum A. Gray, Proc. Am. Acad. 13: 368. 1878.
Astragalus sabulorum S. Wats. (err.| Bibl. Ind. 463. 1878.
Astragalus virgineus Sheldon; Coville, Contr. U. S. Nat. Herb. 4: 88. 1893.
Annual; stem 5-15 cm. high, with spreading branches, canescent with ascending hairs; leaves 3-5 cm. long, the raehis canescent; stipules deltoid, acuminate, 3-4 mm. long; leaflets 9-13, oblong or oblong-oblanceolate, 8-12 mm. long, 2-4 mm. wide, canescent on both sides; peduncles 1-4 cm. long; raceme short, 3-6-flowered ; calyx silky-strigose, the tube 2-2.5 mm. long, the lobes subulate, 2 mm. long; corolla described as purple or violet, but apparently white, with striate banner; petals as in P. annua; pod hirsute, sessile, about 1.5 cm. long and 8 mm. wide, obliquely ovoid, the lower suture gibbous, the upper acute and nearly straight.
Type locality: Southeastern Nevada, near the confluence of Muddy River with Rio Virgin. Distribution: Southern Nevada to northwestern Sonora.

Phaca lerdoensis Rydberg, sp. nov
Annual; stem with decumbent or spreading branches, less than 1 dm. long, hirsutulouscanescent; leaves 2-3 cm. long; stipules distinct, deltoid, 2 mm. long; leaflets 7-1 1, obovate to oblong, about 5 mm. long, hirsute-canescent; peduncles 1-2 cm. long; racemes 3-5-flowered; calyx hirsute, the tube 2 mm. long, the lobes 2 mm. long; corolla purple-tinged with darker veins, 6 mm. long; banner broadly obovate; wings somewhat shorter, the blade oblong-lunate, obtuse, with a long basal auricle; keel-petals broader, strongly gibbous-arcuate, obtuse; pod sessile, hirsute, 12-15 mm. long, gibbous on the lower suture, nearly straight on the upper.
Type collected at Colonia Lerdo, northern Sonora, February, 1904, MacDougal (herb. N. Y. Bot. Gard.).

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 sparsely to densely hairy, Stem hairs hispid to villous, 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 5-9, Leaflets 10-many, Leaves hairy on one or both surfaces, Flowers in axillary clusters or few-floweredracemes, 2-6 flowers, Inflorescences racemes, Inflorescence axillary, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx glabrous, Petals separate, Corolla papilionaceous, Petals clawed, Petals ochroleucous, cream colored, Petals blue, lavander to purple, or violet, 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 p ersistent in fruit, Fruit a legume, Fruit unilocular, Fruit tardily or weakly dehiscent, Fruit oblong or ellipsoidal, Fruit strongly curved, falcate, bent, or lunate, Fruit coriaceous or becoming woody, Fruit exserted from calyx, Fruit beaked, Fruit hairy, Fruit 3-10 seeded, Fruit 11-many seeded, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.

Astragalus sabulonum is a species of milkvetch known by the common name gravel milkvetch. It is native to the Southwestern United States and California, from desert to mountain habitats.

This is a hairy annual herb with stems up to about 26 centimeters long. Leaves are a few centimeters long and are made up of several hairy oval-shaped leaflets. The inflorescence is an open array of 2 to 7 off-white to pale lilac flowers each less than a centimeter in length.

The fruit is a curved, leathery, hairy legume pod up to 2 centimeters long.