Senna pallida var. goldmaniana

  • Title

    Senna pallida var. goldmaniana

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

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

  • Description

    177i. Senna pallida (Vahl) var. goldmaniana Irwin & Barneby, var. nov., omnes inter speciei formas foliolis 2-4-jugis seminumque testa castanea dense minutim foveolata praestans.-MEXICO. Quintana Roo: La Vega [on coast opposite Isla Cancun near 21°06'N; cf. Goldman, Smithson. Miscell. Coll. 115: 24, 242. 1951], 14-26.III. 1901 (fl, fr), E. A. Goldman 632.-Holotypus, US = NY Neg. 10493.

    Slender shrubs, in habit and resinously dotted foliage resembling var. bahamensis, with terete branchlets, glabrous except for minutely puberulent ovary, the mature foliage pallid-glaucescent beneath, the 2-fld racemes borne on depauperately leafy branchlets axillary to coeval lvs.

    Stipules subulate or setaceous 1-5 x 0.2-0.3 mm.

    Primary cauline lvs 4.5-7.5 cm; petiole 12-20 x 0.5-0.6 mm, 1-1.5 times as long as first (or only) interfoliolar segment of lf-stalk; rachis 1-4.2 cm; gland between proximal pair, shortly stipitate, 1.1-2 mm, the head 0.4-0.8 mm diam; lfts 2-4 pairs, accrescent distally, the terminal pair broadly obovate obtuse 2-2.8 x 1-2 cm, 1.3-2 times as long as wide, the venation of 5-6 pairs of camptodrome secondary nerves weakly prominulous on both faces, reticular venulation 0; lvs of branchlets shorter, the lfts always 2-jugate.

    Peduncles 12-17 mm; pedicels 1-2.2 cm; long sepals ±6 mm; long petals ±13-17 mm; filaments glabrous, of 4 median stamens ±1 mm, of 3 abaxial ones ±2.5 mm, the anthers of 4 median stamens abruptly truncate 4.5-4.8 x 1.5 mm, of 3 abaxial ones 5-5.5 mm, with beak ±1.5 mm; style 1.5 mm.

    Stipe of pod 5-7 mm, the body 5.5-9 x 0.55-0.7 cm, the valves simply mounded over seeds; seed 3 x 1.7-2.8 mm, the castaneous testa densely finely pitted overall, the areole 0.7-0.9 x 0.6-0.7 mm.-Collections: 5.

    Habitat not recorded, known only from the n.-e. shoulder of Yucatan Peninsula, Terr. Quintana Roo, Mexico.-FI. II-IV, probably later.

    A remarkable plant, clearly distinct from var. gaumeri, vicariant immediately to the east, in its few large leaflets, those of primary leaves two to four (not 4-6), those of leaves associated with flowering brachyblasts exactly two (not 3-4) pairs; and unique among known forms of S. pallida in its pitted seeds. The same characters distinguish it from var. bahamensis, which has in addition characteristically slender anthers; and from var. pallida, of which the nearest known stations lie some 800 km south westward in Veracruz and 500 km southeastward on Swan Islands in the western Carribean. In general aspect var. goldmaniana is reminiscent of S. holwayana var. absoidea which has leaves similarly simplified down to two pairs of leaflets, but differs, inter alia, in the proportionately very long and slender petiole, 5-9 (not 1-1.5) times as long as the rachis proper.