Senna cana var. hypoleuca

  • Title

    Senna cana var. hypoleuca

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna cana var. hypoleuca (Benth.) H.S.Irwin & Barneby

  • Description

    59b. Senna cana (Nees & Martius) Irwin & Barneby var. hypoleuca (Bentham) Irwin & Barneby, stat. nov. Cassia hypoleuca Martius ex Bentham, in Martius, Fl. Bras. 15(2): 117. 1870.—". . . in campis districtus Adamantium, provinciae Minas Geraes: Martius; inter Cavalcante et Conceiçao prov. Goyaz: Burchell."—Holotypus, Martius s.n., labelled "Campi distr. adam[antini] et in inter[iori] prov. Bahiensis," M! = F Neg. 6239.—The paratypus, presumably Burchell 7933 listed by Bentham (1871, p. 584), was overlooked by us at K; presumably it represents the undescribed entity indicated immediately following var. phyllostegia below.

    Cassia hypoleuca sensu Bentham, 1871, p. 537.

    At anthesis (1-)2-6 m; pubescence of var. cana; stipules erect, linear-attenuate straight 3-5.5 x 0.5-0.8 mm, caducous before full expansion of lf; glands between proximal pair 0, between second and third pair subsessile stoutly claviform-ovoid 0.8-2.5 mm, between distal pair either 0 or, when present, situated behind the pulvinules, next to or adnate to the subulate seta; lfts 3-5(-6) pairs, the distal pair (3.2-)3.5-6.5 x 1.3-2.5(-2.7) cm, (1.7-)2-3 times as long as wide; floral bracts 3-6.5 x 1.6-2 mm; pod 10-15 x 0.4-0.55 cm, compressed-tetragonal, the wings corresponding to the accessory nerves parallel to the ventral suture 1-1.8 mm wide, those parallel to the dorsal suture much narrower; seed-locules 4.5 5.5 x 2.5-3.5 mm.—Collections: 8.

    Disturbed cerrado on sandstone or quartzite, 980-1300 m, highly localized on the upper Rio de Contas in s.-centr. Bahia, especially in the foothills of Pico de Almas near the town of Rio de Contas and the s. foothills of Sa. do Sincora near Barra da Estiva.—Fl. I-IV.—Açoita-cavalo.

    At anthesis var. hypoleuca differs materially from larger-leaved forms of var. cana only in the narrow, less persistent stipules, just as so-called Cassia dyso- phylla was supposed by Bentham to differ from C. velutina. It is now known that the stipular character of C. dysophylla is supported by no other morphological difference and is not correlated with dispersal, and we have been obliged to reduce that species to S. velutina. Here, however, the pod associated with the setiform stipule differs from that of broad-stipulate var. cana in developing not one but two winglike flanges from each valve, one approximate and parallel to the ventral suture, the other approximate and parallel to the dorsal one, yielding a sharply X-shaped cross section.