Senna pilifera var. subglabra

  • Title

    Senna pilifera var. subglabra

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna pilifera var. subglabra (S.Moore) H.S.Irwin & Barneby

  • Description

    63b. Senna pilifera (Vogel) var. subglabra (S. Moore) Irwin & Barneby, comb. nov. Cassia pilifera var. subglabra S. Moore, Trans. Linn. Soc. London II, 4: 346. 1895.—"In paludibus ad Carandajinho juxta Corumba [, Mato Grosso] . . . Jan. [1892] (N. 919.)."— Holotypus, BM! = IPA Neg. 1439 = MO Neg. 2067 = NY Neg. 158.

    Cassia maritima Willenow ex Vogel, Syn. Gen. Cass. 23 & Linnaea 11: 668, descr. ampliat. 1837.—"W[illdenow] Hrb. 7928."—Holotypus, B (hb. Willd. 7928)!

    Cassia mattogrossensis Malme, Arkiv f. Botanik 23A(13): 60. 1931.—"Santa Anna da Chapada [=Chapada dos Guimaraes, n.-e. of Cuiaba, Mato Grosso], 18.V. 1903 [(fl,fr.), Regnell] 11:3380 . . Holotypus, S! = NY Neg. 10476.

    Cassia pilifera sensu Bentham, 1871, p. 536, magna ex parte, syn. incl.

    Emelista pilifera sensu Britton & Rose, 1930, p. 243, basionym. exclus. & syn. 'C. cubensis,' Schery, 1951, p. 70.

    Herbaceous from fibrous roots, sometimes appearing monocarpic, sometimes suffruticose in age, normally much taller and more erect than var. pilifera, the foliage thinner-textured, usually glaucescent beneath, usually finely puberulent on both faces, exceptionally glabrous; petioles 2-6 cm, mostly 0.5-1.2 mm diam; distal lfts 3-6(-7.5) x 1.5-3.4 cm, the tertiary and reticular venulation scarcely or not visible above, faintly raised beneath; pedicels 1.5-2.6 cm; style of var. pilifera; areole of seeds 2-2.5 x 0.3-0.6 mm.—Collections: 52.

    Thickets, open or disturbed woodland, riverbanks and shores, southward along gallery margins in cerrado, becoming locally weedy in hedges and pastures, near sea-level up to 1400 m in Mexico, 1450 m in Peru, 1050 m on the Brazilian Planalto, widespread but highly scattered through parts of tropical N. and S. America: w. and s. Mexico (Sinaloa, near 25°N, to Oaxaca, Chiapas and Veracruz); e. Cuba (Oriente); centr. Panama (Panama and Canal Zone); Cordillera Oriental in n. Colombia (Santander); lowland Pacific Ecuador (Guayas); sources of R. Huancabamba in s.-e. Piura and Cajamarca, Peru; remotely disjunct in the Orinoco valley in Bolivar and Guarico, Venezuela and in lower Amazonian and e. Brazil, from the delta region in Para s. to the headwaters Rio Araguaia in Mato Grosso, of Rio Tocantins in Goias, the Sao Francisco-Doce watershed in s. Minas Gerais, and e. Sao Paulo (Bocaina)—Fl. in Mexico IX-II, Cuba and Panama IX-II, in n. S. America IV-V, in Brazil III-VII.—Acahualera (s. Mexico).

    There can be little question that the Mexican, Cuban, Panamanian and Amazonian plants referred by Bentham and by Britton & Rose to Cassia (or Emelista) pilifera are distinct from genuine S. pilifera of tropical Argentina and adjoining states, for they differ in habit, probably in duration of the root, in size of all flower parts and, most importantly, in the shape of the seed-locules as determined by the smaller size of the differently colored seeds. Collectively they might well be construed as an independent species, but the populations known from Maranhao, Goias and Minas Gerais, while for the most part firmly linked to the northern ones by their seeds and habit of growth, have larger flowers, the measurements of all organs independently overlapping, if only a little, those of typical S. pilifera; and a few of these are ambiguous as to growth-habit, taller certainly than var. pilifera of extreme southeastern Brazil and Argentina but described as diffuse. A line drawn along the Amazon-Parana watershed through the Federal District effectively separates the ranges of the varieties but as they approach this line, from either direction, the more obvious differences become muted. Unfortunately we have as yet too few examples of seeds from the Planalto, which might prove critical in the case of ambiguous specimens.

    Unlike var. pilifera, the present variety is rather uniform in pubescence of the foliage, the leaflets being almost always puberulent on both faces; but the ovary may be either strigulose or pilose, its vesture varying independently of that of the stems or of geography. The holotypus of var. subglabra and Irwin et al. 15267 from Sa. do Morcego on the Goias-Minas border near 15°S are notable for the complete loss of the long lustrous setae usually thought characteristic of C. pilifera, but are not otherwise different from compatriot populations. The epithet sub glabra is for the most part inappropriate and misleading.