Monographs Details: Senna pistaciifolia var. pistaciifolia
Authors:Howard S. Irwin, Rupert C. Barneby
Authority: Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 2: 455-918.
Discussion:

153a. Senna pistaciifolia (Humboldt, Bonpland & Kunth) Irwin & Barneby var. pistaciifolia. Cassia pistaciifolia Humboldt, Bonpland & Kunth, 1824, l.c., sens. str.— Crescit locis montosis, inter urbem Popayan et Meneses, alt. 700 hex."—Holotypus, consisting of 1 lf + pods, ticketed "n. 2133. Popayan," P-HBK! isotypus, B (hb. Willd. 7946)!— Chamaesenna pistaciifolia (Humboldt, Bonpland & Kunth) Britton ex Britton & Killip, Ann. N.Y. Acad. Sci. 35(3): 179. 1936.

Chamaesenna colombiana Britton & Killip, Ann. N.Y. Acad. Sci. 35(3): 179. 1936.—"Vicinity of Medellin, Colombia. Type from Boqueron, January 5, 1928, [Rafael A.] Toro 866, type . . . Cucaracho, Antioquia, December 25, 1927, Toro 839. Antioquia, Jervise-, Trianar— Holotypus, Toro 866, NY! — NY Neg. 4958; paratypi, Toro 839, NY! Jervise s.n., K! Triana s.n., K!

Lfts either glabrous or softly pilosulous beneath; otherwise as given in varietal key.—Collections: 7.

Habitat little known, to be expected in disturbed upland forest or residual thickets in formerly forested valleys, ±1200-2000 m, local in the w. Andes of Colombia, especially in the Cauca valley between Medellin and Popayan (Antioquia and Cauca), and apparently disjunct in central Andean Ecuador (Chimborazo).—Fl. X-II(-?).

The populations in the Cauca valley that differ from the holotypic phase of Cassia pistaciifolia in having leaflets glabrous on both faces do not differ otherwise, and we cannot maintain even varietally the two species of Chamaesenna postulated by Britton & Killip. The disjunct record from Ecuador (Huigra, Rose 23505) is based on plants bearing year-old pods and newly expanding leaves, and may represent a distinct form. Rose recorded it as a shrub, with hard wood used for house-building.