Thompson's Peteria

Peteria thompsonae S. Wats. Am. Nat. 7: 300. 1873
Stem herbaceous, except at the very base, 2-4 dm. high, glabrous or nearly so, strawcolored, strict; stipular spines 2-5 mm. long; leaves 6-13 cm. long; rachis strigose; leaflets 13-21, oval, 6-15 mm. long, rounded at the apex, glabrous above, strigose beneath; raceme solitary, terminal, 1-2 dm. long; bracts linear-subulate, deciduous; pedicels 5-8 mm. long; calyx-tube 7-8 mm. long, hirsute and glandular-pubescent, the lobes linear-subulate, attenuate, 7-8 mm. long, the upper two united half their length; corolla 15-20 mm. long, ochroleucous; blade of the banner suborbicular ; those of the wings and keel-petals broadly obovate, with a rounded basal lobe; pod about 5 cm. long, 4 mm. wide, glabrous, about 6-seeded; seeds oval, compressed.
Type locality: Kanab, southern Utah.
Distribution: Central and southern Utah

Perennial, Herbs, Plants with rhizomes or suckers, Tubers or tuberous roots present, Nodules present, Stems erect or ascending, Stems or branches arching, spreading or decumbent, Stems less than 1 m tall, Trunk or stems armed with thorns, spines or prickles, 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 persistent, Stipules free, Stipules spinose or bristles, Leaves compound, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 10-many, Leaves glabrous or nearly so, Inflorescences racemes, Inflorescence terminal, Inflorescence leaf-opposed, Bracts very small, absent or caducous, Flowers zygomorphic, Calyx 5-lobed, Calyx gland-dotted or with glandular spot, Calyx hairy, Petals separate, Corolla papilionaceous, Petals clawed, Petals white, Petals ochroleucous, cream colored, Petals pinkish to rose, Banner petal ovoid or obovate, Wing petals narrow, oblanceolate to oblong, Wing petals auriculate, Keel petals auriculate, spurred, or gibbous, Stamens 9-10, Stamens diadelphous, 9 united, 1 free, Filaments glabrous, Style terete, Style with distal tuft of hairs, Fruit a legume, Fruit stipitate, Frui t unilocular, Fruit freely dehiscent, Fruit elongate, straight, Fruit oblong or ellipsoidal, Fruit exserted from calyx, Fruit compressed between seeds, Fruit glabrous or glabrate, Fruit 3-10 seeded, Seeds ovoid to rounded in outline, Seed surface smooth, Seeds olive, brown, or black.

Peteria thompsoniae is a species of flowering plant in the legume family known by the common names spine-noded milkvetch and Thompson's peteria. It is native to the western United States, where it grows in salt desert shrublands in soils of volcanic ash origin, and in alluvial fans. It is a spiny perennial herb growing from a taproot and rhizome system, its stem growing 20 to 60 centimeters tall. The leaves are made up of several pairs of oval leaflets. The inflorescence, a spikelike raceme at the top of the stem, produces white or pinkish pealike flowers up to 2.5 centimeters long, its base encapsulated in a tubular calyx of glandular sepals. The fruit is a leathery, slightly inflated legume pod up to 6 centimeters long.