Senna wislizeni var. wislizeni

Title

Senna wislizeni var. wislizeni

Author(s)

Howard S. Irwin, Rupert C. Barneby

Scientific Name

Senna wislizeni (A.Gray) H.S.Irwin & Barneby var. wislizeni

Description

193c. Senna wislizeni (A. Gray) Irwin & Barneby var. wislizeni. Cassia wislizeni A. Gray, Pl. Wright. 1: 60. 1852, sens. str.-"[Chihuahua:] Carizal and Ojo Caliente, south of El Paso, Dr. Wislizenus. "-Holotypus (Isely, 1975, p. 210), GH!-Palmerocassia wislizeni (A. Gray) Britton ex Britton & Rose, N. Amer. Fl. 23(4): 254 ("Wislizeniian impossible genitive). 1930.

Cassia wislizeni sensu Bentham, 1871, p. 574; Wooton & Standley, 1915, p. 334; Turner, 1959, p. 76, map 37 (Texas only); Kearney & Peebles, 1960, p. 405; Isely, 1975, p. 133, map 61 (U.S. only). Cassia wislizeni var. wislizeni sensu Irwin & Barneby, 1975, p. 16 (in clave), fig. 2 (map).

Secondary thorny branchlets 0, but the raceme axes sometimes stiffly or almost pungently persistent; vesture strigulose, the hairs up to 0.2-0.45 mm; primary lvs 12-34 mm, with 3 or 3-4 pairs of lfts, the largest 4-10 x 2.5-7.5 mm; ovules 22-25; otherwise as given in key.-Collections: 25.

Larrea scrub in foothills of desert mountains, often but not exclusively on limestone, 850-1570 m, widespread over the n. lobe of the Chihuahuan Desert from s.-e. Chihuahua and n.-w. Coahuila to the Rio Grande valley in trans-Pecos Texas (upstream from Presidio Co.), far s.-w. New Mexico and extreme s.-e. Arizona, thence feebly s.-w. and down to ±500 m into the Sonoran Desert in n. centr. Sonora.-Fl. (IV-)VI-XI.-Pinacate; yerba del pinacate.

This variety and the next differ collectively from the two foregoing in the glossy texture of the pod’s valves which become elevated over each seed in the form of two parallel transverse ridges across the proximal and distal edges of the locule. These ridges are sometimes connected by a vertical one, forming over the seed a depressed tent or blunt-angled pyramid such as is characteristic of some varieties of S. pallida.