Monographs Details: Senna cana var. phyllostegia 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.
Description:Variety Description - At anthesis 1.5-3 m; vesture of var. pilosula; stipules lance-caudate, falcately incurved to vertical, from point of attachment 4.5-10 mm long, at base variably dilated and reflexed 0.7-2(-3) mm wide, when much dilated auriculate-amplexicaul; glands at all except proximal and distal pairs, stipitate; lfts (4-)5-7(-8) pairs, the distal pair elliptic or lance-elliptic acute or obtuse (2.3-)2.5-5 x (0.7-)0.9-1.5(-1.9) cm, 2.3-3.3(-3.8) times as long as wide; floral bracts foliaceous ovate-acuminate (4-)6-12 x 2.5-4 mm, persistent into full anthesis; longest petal 18-24 mm; pod unknown.—Collections: 7. [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 incumbently pilosulous. Bracts foliaceous, ovate-acuminate (4-)6-12 x 2.5-4 mm, long persistent; locally abundant in Sa. do Sincora and vicinity, s. just into n.-e. Minas Gerais."]
Distribution and Ecology - Disturbed woodland and rocky slopes along rivers, on sandstone or laterite, 400-1000 m, locally abundant on the sources of rios Paraguaçu and de Contas in Sa. do Sincora, and at one distant station on Rio Jequetinonha (Itaobim) in n.-e. Minas Gerais.—Fl. I-IV.
Discussion:This variety closely resembles the last at all essential points, but differs in the enlarged and apparently more persistent bracts which lend a distinctive aspect to the flowering raceme. Contrary to a general rule, that bracts and stipules in Cassieae tend to increase or wane together, the stipules of var. phyllostegia are on the average less, not more dilated than those of var. pilosula. In Sa. do Sincora var. phyllostegia is easily distinguished from vicariant (perhaps marginally sympatric) vars. cana and hypoleuca by a combination of pilosulous vesture and broad bracts. Its disjunct occurrence within the range of var. pilosula in northeastern Minas Gerais is difficult to explain. The station lies on the main Brasilia-Salvador highway at the crossing of the Jequetinonha, and the possibility that this floriferous senna is only adventive outside Sa. do Sincora cannot be ruled out.
Minas Gerais Brazil South America