Slimleaf Prairie Clover

Petalostemon tenuifolius A. Gray, Proc. Am. Acad. 11: 73 1876.
Kuhnistera tenuifolia Kuntze, Rev. Gen. 192. 1891.
A perennial, with a woody base; stem ascending or erect, slender, 1.5-3 dm. high, pale, glabrous, striate, branched; leaves ascending, 3-4 cm. long; stipules subulate-setaceous; leaflets 3-5, linear or narrowly linear-oblanceolate, 8-18 mm. long, involute, blunt, glabrous or nearly so, sparingly glandular; spikes cylindric, in fruit 2-5 cm. long, 8 mm. thick; bracts silky-villous throughout, ovate, abruptly contracted into a subulate tip, slightly exceeding the buds; calyx silky-villous, 4 mm. long; lobes triangular-lanceolate, about as long as the tube; corolla rose-purple; blade of the banner cordate, 3 mm. long and as broad, nearly equaling the claw; blades of the other petals oblanceolate, 3 mm. long; pod pubescent.
Type locality: Arkansas at the crossing of Red River.
Distribution: Kansas to Arkansas and Texas.

Petalostemon porterianus Small, Fl. SF. U. S. 631, 1332 1903.
A perennial, with a woody base; stems 2-4 dm. high, more or less branched, sparingly pubescent, striate; leaves ascending, 3-5 cm. long; stipules subulate-setaceous; leaflets 3-5, linear, 8-15 mm. long, strongly involute, sparingly pubescent or glabrous, conspicuouslypunctate; spikes oblong-cylindric, in fruit 1.5-4 cm. long, 8 mm. thick; bracts obovate, acuminate, pubescent with a dark glabrate tip, longer than the calyces and buds; calyx villous, distinctly 10-ribbed, 4 mm. long; lobes lanceolate or triangular-lanceolate, shorter than the tube; corolla rose-purple or violet; blade of the banner subcordate, rounded or truncate at the apex,
2 mm. long, the claw 3 mm. long; blades of the other petals broadly oblong, 3 mm. long,
rounded at the apex, truncate at the base, the claws 1 mm. long; pod pubescent.
Type locality: "Leavenworth, Arkansas, to El Paso, Texas." Distribution: Texas.

Petalostemon rothrockii Rydberg, sp. nov
Petalostemon lenuifolius Rothr. Bot. Wheeler's Surv. 99, in part. 1878.
A perennial, with a thick woody base; stems several, 3-5 dm. high, glabrous, striate, conspicuously punctate; leaves ascending, 3-5 cm. long; stipules subulate-filiform; leaflets oblong or linear-oblong, obtuse or retuse, thick, about 1 cm. long, light-green above, glaucous and strongly punctate beneath; spikes long-peduncled, cylindric or oblong, in fruit 8-9 mm. thick, 1-5 cm. long; bracts broadly obovate, short-acuminate, dark, short-pilose or glabrous, about equaling the calyces; calyx 3.5 mm. long, long-pilose; lobes acute, about equaling the tube, the lower three triangular-lanceolate, the upper two ovate; blade of banner broadly oblong, rounded or retuse at the apex, truncate or subcordate at the base, 3.5 mm. long, the claw 5 mm. long; blades of the other petals 3.5 mm. long, oblong, acute at the base, the claws 2 mm. long; pod obliquely obovate, pubescent.
Type collected in Arizona, 1874, Rolhrock (Wheeler Exp., in herb. Columbia Univ.).
Distribution: Southern Utah and Arizona.

Perennial, Herbs, Taproot present, Nodules present, Stems erect or ascending, Stems or branches arching, spreading or decumbent, Stems prostrate, trailing, or mat forming, Stems less than 1 m tall, Plants gland-dotted or with gland-tipped hairs, Stems solid, Stems or young twigs sparsely to dens ely hairy, Leaves alternate, Leaves petiolate, Stipules inconspicuous, absent, or caducous, Stipules setiform, subulate or acicular, Stipules deciduous, Stipules free, Leaves compound, Leaves pinnately 3-foliolate, Leaves odd pinnate, Leaf or leaflet margins entire, Leaflets opposite, Leaflets 3, Leaflets 5-9, Leaves glandular punctate or gland-dotted, Leaves glabrous or nearly so, Inflorescences spikes or spike-like, Inflorescence terminal, Bracts conspicuously present, Calyx 5-lobed, Calyx hairy, Petals separate, Petals clawed, Petals blue, lavander to purple, or violet, Banner petal narrow or oblanceolate, Banner petal ovoid or obovate, Wing petals narrow, oblanceolate to oblong, Wing tips obtuse or rounded, Keel tips obtuse or rounded, not beaked, Fertile stamens 5, Stamens monadelphous, united below, Filaments glabrous, Style terete, Fruit a legume, Fruit unilocular, Fruit indehiscent, Fruit elongate, straight, Fruit oblong or ellipsoidal, Fruit enclosed in calyx, Fruit glabrous or glabrate, Fruit hairy, Fruit gland-dotted or with gland-tipped hairs, Fruit 1-seeded, Seeds reniform, Seeds cordiform, mit-shaped, notched at one end, Seed surface smooth, Seeds olive, brown, or black.