Monographs Details: Senna cana (Nees & Mart.) H.S.Irwin & Barneby var. cana
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.
Synonyms:Cassia cana Nees & Mart.
Description:Variety Description - At anthesis 1.5-5 m, the trunk up to 1 dm diam but usually much less; leaflets usually densely pannose-tomentulose beneath, the pubescence all white, or pallid striped with rufous along the veins, or all rufescent, rarely glabrescent but the hairs still very short and crisped; stipules reflexed, lunately lance-acuminate or very obliquely semi-ovate-caudate, from point of attachment 3-12 mm long and there (1-) 1.5-7 mm wide, palmately venulose, the blades resembling lfts in texture, pubescence and revolute margins, deciduous rather tardily but before the lf; glands usually between all pairs but the proximal, rarely there also, at distal pair 0-2, when 2 one between and one behind the pulvinules; lfts 4-8 pairs, the distal (or penultimate) pair 2-6.5(-7) x (0.7-)0.8-2.2 cm, (1.8-)2-3.3(-3.5) times as long as wide; floral bracts 3-5.5 x 1-2 mm; pod (little known) broadly V-shaped in cross section, the wings forming the extremities of the V’s arms; seed-locules 5-5.5 x 3.5-4 mm.—Collections: 25. [Key: "Vesture of the lower face of lfts tomentulose, composed of tightly crisped, ± matted hairs mostly 0.1-0.25 mm, commonly concealing the whole surface, the intervenium, however, sometimes more thinly hairy than the always pannose-tomentulose veins; upland interior and w. Bahia to adjac. e.-centr. Goias and n.-centr. and w.-centr. Minas Gerais. Stipules ± dilated at base, the herbaceous blade reflexed and auriculate-amplexicaul, at point of attachment 1-7 mm wide, persistent into maturity of lf; lfts 4-8 pairs; valves of pod narrowly winged along each side of the ventral suture only, the seed-locules extending to the dorsal margin of the fruit; widely dispersed as above."]

Distribution and Ecology - Cerrado and caatinga thickets, sometimes among tumbled rocks along streams, 530-1125 m, locally common along the crest and both slopes of Chapada Diamantina and Sa. do Espinhaço in lat. 10°20'-19°S, between Sa. do Curral Feio in n.-centr. Bahia and mun. Diamantina in centr. Minas Gerais, and scattered around the w. sources of Rio Sao Francisco from Rio Preto in n.-w. Bahia s. along Espigao Mestre and Sa. Geral de Goias to the headwaters of Rio Paracatu in w. centr. Minas Gerais.—Fl. I-IV(-V).

Discussion:We include in var. cana what appears to be a clinal series progressing from small-leaved bushes, seldom over 2 m tall, with 4-8 pairs of relatively small leaflets (-3.5, rarely -4 cm), to potentially or actually arborescent, ampler-leaved and sometimes larger-flowered types, with only 4-6 pairs of longer leaflets (to 3-6.5 cm). The series coincides roughly with dispersal, the smallest forms being found on the heights of north-central Bahia, the largest in northern and western Minas Gerais. The extremes are visually striking, but we have found no decisive discontinuity in the series. A marked minor variant (Harley 15994, K, M, NY) from Sa. do Sincora differs in its vesture of appressed rufous hairs and is perhaps more closely related to sympatric S. cana var. phyllostegia, although retaining the small floral bracts of var. cana.
Distribution:Bahia Brazil South America| Minas Gerais Brazil South America|