Tephrosia tenella

Herbs. Stems erect to decumbent or ascending, (8–)10–50(–100) cm, sparsely strigulose to glabrescent. Leaves: petiole 10–30 mm; leaflets (3 or)5–9(or 11), blades linear to linear-oblong, narrowly oblong, or oblong-elliptic, 15–40 × 2–6 mm, length 5–9 times width, apex acute to obtuse or rounded, abaxial surface sparsely strigulose, adaxial glabrous. Racemes terminal and axillary, (1–)8–17-flowered, 10–30 cm; floral bracts subpersistent, setaceous-subulate. Flowers: corolla pink to rose-pink or rose-purple, aging darker reddish to purple, 6–9 mm; stamens diadelphous; style glabrous. Legumes 30–50 × 3–4 mm, sparsely strigulose.

Phenology: Flowering Apr–Oct(–Nov).
Habitat: Open slopes and flats, canyon slopes and bottoms, ledges, crevices, among boulders, washes, gravelly alluvium, desert scrub, desert grasslands, mesquite-acacia grasslands, oak savannas, oak-juniper woodlands, pine-oak woodlands, roadsides.
Elevation: (700–)800–1900(–2000) m.

Ariz., N.Mex., Tex., Mexico, Central America.

Discussion

D. Isely (1998) noted that Tephrosia tenella seems a peripheral manifestation of the widespread T. purpurea complex. F. Shreve and I. L. Wiggins (1964) identified the species in the Sonoran Desert as T. purpurea (the type of which is from Africa) and observed that plants in the northern part of its range (called T. tenella) seem to have narrower, more acute leaflets but intergrade completely with ones at more southern localities.

Tephrosia vicioides Schlechtendal has been suggested to be the correct name for these plants (R. McVaugh 1987).

In Tephrosia tenella as identified here, most commonly the taproot becomes thick and distinctly perennial, and the plants often develop a woody, caudex-like region as well. Some plants arise from a slender taproot, with stems 8–30 cm and (1 or)2–5 flowers per raceme. Glabrous-styled taxa were not included in the study of Tephrosia by C. E. Wood Jr. (1949).

Selected References

None.

Lower Taxa