Monographs Details: Senna cana var. calva H.S.Irwin & Barneby
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.
Family:Caesalpiniaceae
Description:Variety Description - Closely resembling var. phyllostegia, but the leaflets glabrous or thinly fuscous- strigulose beneath with minute appressed hairs; bracts early caducous. [Key: "Vesture of lower face of lfts pilosulous with loosely incumbent, weakly sinuous hairs up to 0.3-0.6 mm, or minutely sparsely strigulose, or quite glabrous; Atlantic slope of Chapada Diamantina s. through e. Minas Gerais to Rio Doce in Espirito Santo. Stipules linear-setiform erect, at base less than 1 mm wide, early caducous; valves of pod narrowly winged along each side of both sutures, the seed-locules consequently extending to neither margin of the fruit; local on upper Rio Contas in Bahia. Lower face of leaflets glabrous or minutely sparsely appressed-strigulose; bracts early caducous; n. Sa. do Sincora and vicinity."]

Distribution and Ecology - Campo rupestre, 800-1000 m, locally abundant and sometimes dominant about the sources of R. Paraguay in centr. highland Bahia (Lengois, Mucuge, Seabra).—Fl. Ill-VI.

Discussion:This was taken at first to be a simple glabrate variant of var. phyllostegia, but with seven collections now available for comparison it emerges as a distinct entity differing not only in the hairless or almost hairless foliage but also in the early caducous bracts. Unaccounted for up to this point in our census of ser. Laxiflorae is a set of ambiguous, mostly maimed or imperfect specimens from southwest Para (Sa. do Cachimbo), east-central Goias (Chapada doe Veadeiros), adjoining Bahia (Espigao Mestre), southern Maranhao (Rio Balsas region, where sympatric with S. lechriosperma) and southern Piauf (near Caracol) which seem to represent an independent entity, as yet indefinable in exact terms, both morphologically and geographically intermediate between S. cana and S. velutina, while retaining a certain individuality of facies. These plants have the pod and elongate inflorescence of S. velutina, but their larger leaves have more numerous, proportionately narrower leaflets (±3-4.5, not 2-3 times as long as wide). The short pilosulous vesture of leaves together with dorsally glabrous sepals and 5-8 pairs of leaflets suggest a robust form of S. cana var. pilosula, but the compressed, laterally costate but not winged pod cannot be accommodated in S. cana. Our material (cf. Irwin et al. 14806, 24336, NY; de Haas et al. 292, NY; Eiten 4618, NY; Luetzelburg 1534, M = IPA Neg. 1375) consists largely of immature flowering and over-mature fruiting specimens to which we do not venture to attach a name. May through July are the months during which full anthesis and early fruit can be expected. A collection from Sa. do Cachimbo in southwest Para (Prance et al. 25056, US), barely flowering in November, suggests either a westward extension of the foregoing or a distinct but closely related form.
Distribution:Bahia Brazil South America|