Park Milk Vetch

Phaca leptalea (A. Gray) Rydb. Bull. Torrey Club 40; 48. 1913.
IPhaca panciflora Nutt.; T. & G. Fl. N. Am. 1: 348. 1838.
Astragalus pauciflorus A. Grav, Proc. Acad. Phila. II. 7: 60. 1863. Not .4. pauciflorus Pall. 1800;
nor A. pauciflorus Hook. 1831. Astragalus leptaleus A. Gray, Proc. Am. Acad. 6: 220. 1864. Tragacantha leptalea Kuntze, Rev. Gen. 946. 1891.
Perennial, with a slender cespitose root stock; stems slender, decumbent or spreading, 1-2 dm. long, sparingly strigose; leaves 4-7 cm. long; lower stipules connate, deltoid, 3 mm. long, the upper lance-subulate; leaflets 15-25, lance-linear to oblong, often acute, 5-12 mm. long; peduncles 2-5 cm. long, slender; racemes 2-5-flowered; calyx more or less black-hairy, the tube
3 mm. long; the lobes subulate, 2 mm. long; corolla white; banner obovate, emarginate, nearly 1 cm. long; wings 8 mm. long, the blade oblong, with an acute basal auricle; keel-petals 6 mm. long, the blade broadly lunate, rounded at the apex, purple-tipped; pod sessile, strigose with black hairs, ellipsoid, 1 cm. long, 5 mm. wide; seeds obliquely round-reniform, 2 mm. long.
Type locality: Valleys of the Rocky Mountains, in South Park, Colorado. Distribution: Mountains of Colorado.

Perennial, Herbs, Plants with rhizomes or suckers, Taproot present, Nodules present, Stems or branches arching, spreading or decumbent, Stems prostrate, trailing, or mat forming, 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 conspicuous, Stipules membranous or chartaceous, Stipules persistent, Stipules connate to each other, forming a tuber or sheath, Leaves compound, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 10-many, Leaves hairy on one or both surfaces, Flowers in axillary clusters or few-floweredracemes, 2-6 flowers, Inflorescence axillary, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals white, 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, Stamen s diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style persistent in fruit, Fruit a legume, Fruit stipitate, Fruit unilocular, Fruit tardily or weakly dehiscent, Fruit oblong or ellipsoidal, Fruit rugose wrinkled or reticulate, Fruit exserted from calyx, Fruit beaked, Fruit hairy, Fruit 3-10 seeded, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.

Astragalus leptaleus is a species of flowering plant in the legume family known by the common name park milkvetch. It is native to the Rocky Mountains of the United States, where it occurs in Idaho, Montana, Wyoming, and Colorado.

This rhizomatous perennial herb grows from a taproot and underground branching caudex unit. It has one or more stems up to 20 centimeters long and may form mats. Each leaf is made up of up to 27 leaflets. Flowers are borne in calyces of sepals coated in black hairs. The flowers are cream-white with a purple spot near the tip of the keel. The fruit is a legume pod up to 2.5 centimeters long which is covered in black and white hairs. Blooming time is June through August.

This is mainly a plant of wetlands, often growing on streambanks with willows, such as Salix geyeriana. It grows in the ecotone between wet river habitat and drier upland sites. Common associated plants include Poa pratensis, Juncus balticus, and Sisyrinchium idahoense. It may occur with rare plants such as Astragalus diversifolius, Phlox kelseyi, Salix candida, Carex livida, Primula alcalina, and Lomatogonium rotatum.

The main threats to this species include those associated with habitat modification, such as the conversion of meadows to hay fields. Other threats include livestock grazing, off-road vehicles, and introduced species of plants.

Astragalus leptaleus adalah spesies tumbuhan yang tergolong ke dalam famili Fabaceae. Spesies ini juga merupakan bagian dari ordo Fabales. Spesies Astragalus leptaleus sendiri merupakan bagian dari genus Astragalus. Nama ilmiah dari spesies ini pertama kali diterbitkan oleh A.Gray.

Astragalus leptaleus là một loài thực vật có hoa trong họ Đậu. Loài này được A.Gray miêu tả khoa học đầu tiên.