Senna pallida var. bahamensis

  • Title

    Senna pallida var. bahamensis

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna pallida var. bahamensis H.S.Irwin & Barneby

  • Description

    177j. Senna pallida (Vahl) var. bahamensis Irwin & Barneby, var. nov., ab aliis speciei formis antheris angustis ±1-1.2 mm diam, mediis 4 rostro oblique terminali (nec laterali) dehiscentibus diversa.-BAHAMA ISLANDS. New Providence: near Nassau, 26.1.1903 (fl, fr), A. H. Curtiss 50.-Holotypus, NY; isotypus, US.

    Slender shrubs 1.5-4 m with flexuous terete lustrous lenticellate annotinous branchlets, the hornotinous branchlets with lf-stalks and pallid lower face of strongly 2-colored lfts scattered with lustrous resinous dots, usually glabrous up to the thinly pilosulous (exceptionally also glabrous) ovary, rarely (Atwood Cay) pilosulous with fine incumbent hairs ±0.4 mm, the inflorescence axillary and incipiently paniculate, the (l-)2(-3)-fld racemes mostly borne on very slender, usually leafless branchlets axillary to coeval lvs, these (especially early in season) sometimes reduced to 1 or 2 pseudofasciculate peduncles.

    Stipules linear-attenuate or falcately linear-oblanceolate, 3-6 x 0.2-1 mm.

    Primary lvs 4.5-9(-11) cm; petiole 10-22 mm, 2-3 times as long as first inter- foliolar segment of rachis; rachis (1.5-)2-5(-7) cm; gland between proximal pair 1.8-3 mm, the head 0.5-1.1 mm diam; lfts (3-)4-7(-8) pairs, accrescent upward, the distal pair obovate or broadly oblanceolate obtuse or emarginate, (1.6-) 1.9-3.5 x (0.6-)0.8-1.5(-1.6) cm, 1.5-2.8 times as long as wide, the venation of (5-)6-8(-9) pairs of camptodrome (and often fainter intercalary) secondary veins either faintly raised beneath or on both faces or fully immersed, a fine tertiary venulation sometimes faintly discolored beneath but not prominent.

    Peduncles 2-12(-15) mm; pedicels 11-18 mm; long sepals 5-8 mm; long petals 14-19(-21) mm; androecium glabrous, the filaments of 4 median stamens 1-2.2 mm, of 3 abaxial ones 2-3.5 mm, the anthers of median ones 3-4 mm, of 3 abaxial ones 3-4.5, the beak 1-1.4 mm.

    Stipe of pod 4-7 mm, the body (5-)6-9.5(-10) x 0.4-0.55 cm, the valves simply raised over seeds, not pyramidally so, the interseminal septa 3-3.7 mm apart; seeds 2.5-3.2 x 2-2.7 mm, the areole 0.5-0.9 x 0.3-0.6 mm.-Collections: 37.

    Coppice and beach scrub, locally abundant especially in disturbed and ruderal habitats, below 70 m, widespread in the Bahamas from New Providence and Eleuthera s.-e. to Samana Cay and Acklin I.; South Caicos I.; n.-e. and extreme e. Cuba in Camaguey (Cayos Romano and Paloma) and Oriente (Baracoa to Cabo Maisf). Fl. (IX-)XI-II(-III).-Cultivated in U.S.A., Hawaii, and perhaps elsewhere.-West Indian Gorse.

    The var. bahamensis is separated physically from other forms of its species by discontinuities, west to Yucatan, southwest to Honduras and south to Colombia, nowhere less than 900 km wide; and morphologically by the slender anthers gently contracted at apex rather than premorsely truncate. On Caicos Islands its range narrowly overlaps that of S. angustisiliqua var. inaguensis and on Cuba impinges on that of S. robiniifolia, but it is distinguished from both of these by the biporose dehiscence of the median anthers and by the relatively short and narrow pod. In general appearance and detail var. bahamensis is essentially monomorphic, relatively small-flowered by comparison with some continental S. pallida, and glabrous except for the exceptional population on Atwood Cay (Wilson 7370, F, NY) already mentioned in our discussion of the species.

    Writing from Kew to Dr. Britton in 1924, N. E. Brown (NY, ms) mentioned a specimen of Cassia biflora preserved in the Dale Herbarium at BM, collected in the Bahamas before 1739, possibly the oldest specimen of S. pallida extant. Brown suggested that this might be conspecific with the plant seen by Linnaeus in Clifford’s garden at Hartekamp in 1736 which was to become the typus of Cassia biflora L. Britton in his reply to Brown wrote that "in working out the Bahama Flora ... I came to the conclusion that the Bahama plant would prove to be [C. biflora], more by inspiration perhaps than for any other reason." There seems to be no substantial connection, however, between the two.

    Old specimens collected by Macfadyen (K), presumably on Jamaica, apparently represent this variety. We have no modern evidence of its occurrence on the island.