Monographs Details: Senna silvestris subsp. silvestris var. guaranitica
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 1: 1-454.
Discussion:

3c. Senna silvestris (Vellozo) subsp, silvestris var. guaranitica (Chodat & Hassler) Irwin & Barneby, stat. nov. Cassia guaranitica Chodat & Hassler, Bull. Herb. Boissier II, 4: 824. 1904.—. . in campis Ipe Hu, Sierra de Maracayu, Nov. n. 5338; in altoplanitie pr. flumen Corrientes, Dec., n. 5889.—Lectoholotypus, Hassler 5338, G! isotypus, NY! paratypi, Hassler 5889, G, NY!

Cassia guaranitica fma. latifolia Chodat & Hassler, l.c. 1904.—". . . in valle fluminis Yaca, Dec., n. 6683."—Holotypus, Hassler 6683, G! isotypus, NY!

Shrub or subshrub at anthesis 1-3 m, either glabrous except for puberulent pulvinules or (rarely) the stems and lower face of lfts pilosulous with straight ascending hairs; lvs 13-28 cm; lfts (7-)8-11 (-12) pairs, the largest (near or beyond middle of lf) ovate 4-7 x 1.4-2.8 cm, 2.3-3.3 times as long as wide, at base deeply cordate, the sinus often as deep as the short pulvinule (1.5-2.5 mm), the firmly chartaceous lustrous blades reticulate on both faces; longer sepals 8-10.5 mm; petals 12-20 mm; ovary glabrous; ovules 26-32; body of pod 8-14 x (1 -) 1.2- 1.7 cm, the locules 1-seriate.—Collections: 12.

Cerrado, and becoming weedy in roadside thickets, 200-550 m, locally abundant in the triangle formed by the parallel 19°S, Rio Paraguai and Rio Parana in s. Mato Grosso and s.-e. Paraguay.

The distinct facies of Cassia guaranitica is due entirely to the relatively small size of the stiffly chartaceous lustrous leaflets which, because of their cordate base and short pulvinule, appear to stand subsessile against the leafstalk. Hassler’s Paraguayan specimens are almost wholly glabrous, but similar plants from southern Mato Grosso (e.g. Hatschbach 33094, NY) have dorsally pilosulous leaflets. The flower and pod are exactly those of var. silvestris. On upper Rio Apa that marks the Brazil-Paraguay frontier var. guaranitica is sympatric or almost so with subsp, bifaria var. unifaria, instantly distinguished by its densely yellowish-pubescent, alveolate-reticulate leaflets and coarsely veiny pod.