Senna pallida var. triquetripes

  • Title

    Senna pallida var. triquetripes

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

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

  • Description

    177m. Senna pallida (Vahl) var. triquetripes Irwin & Barneby, var. nov., foliolis numerosis (plerumque 10-15-jugis) subtillime penniveniis (nec dorso reticulatis) cum var. quiedondilla proxime congrua, ab ea foliorum petiolo breviori rachique dorso acute carinato de latere alis ad pulvinules constrictis ornato ideo triquetro, ulterius verosimiliter seminis areola majori diversa.-MEXICO. Guerrero: distr. Montes de Oca [=mun. La Union], San Antonio Buenos Aires, 20.X. 1937 (fl), G. B. Hinton 11512.-Holotypus, NY; isotypi, K, MICH, US.

    Arborescent shrubs 3-5 m, with very slender, angulate-sulcate hornotinous branchlets, appearing glabrous but the young stems and lf-stalks minutely puberulent, the strongly bicolored lfts either glabrous or bearing a tuft of hairs dorsally at the anterior basal angle of midrib, the 2-fld racemes arising singly from axils of primary coeval lvs and shorter than them or some ultimately forming a small leafless terminal exserted panicle.

    Stipules linear-setiform or -subulate 1.5-3.5 x 0.15-0.35 mm.

    Major lvs 7-13.4 cm; petiole (3.5-)6-15(-18) mm, at middle 0.4-1 mm diam, 2-3(-5) times as long as first interfoliolar segment of rachis; rachis 5-9.5 cm, sharply keeled dorsally and relatively broadly winged laterally, the wings constricted at insertion of lfts; gland between proximal pair 1.5-3 x 0.5-1 mm; lfts 10-15 pairs, not (except in some smaller distal lvs) accrescent upward, in outline oblong-elliptic obtuse or deltately acute, conspicuously mucronulate, the longer ones (16-) 18 24( 27) x 4.5-8(-9) mm, 3-4 times as long as wide, the delicate pinnate secondary venation of ±5-7 pairs of camptodrome veins fully immersed or rarely obscurely prominulous above, faintly discolored but not prominulous beneath, the tertiary venulation, when visible, faint and random.

    Peduncles 11-27 mm; pedicels 16-25 mm; long sepals 6.5-9.5 mm; long petals 23-36 mm; filaments of 4 median stamens (glabrous or puberulent, free or basally confluent) 1.2-1.7 mm, of 3 abaxial ones 2.5-5.5 mm, the anthers of 4 median stamens 4-5.2 mm, of 3 abaxial ones 6.5-8, the beak 2.6-3 mm; style 1-1.4 mm.

    Stipe of pod ±6 mm, the body 13-19 x 0.5-0.6 cm, resembling that of var. lemniscata but not twisted; seeds (few seen) ±4-5 x 3 mm, the areole 2.7-3.5 x 1.5 mm.-Collections: 6.

    Cool oak-pine and alder woodland, 1000-1550 m, apparently local along crest of Sa. Madre del Sur in Guerrero (mun. La Union, Ajuchitlan) and s. Oaxaca (distr. Pochutla, Juquila), Mexico.-Fl. X-II.

    This still imperfectly known variety is sympatric in Guerrero with var. quiedondilla and resembles it in number and venulation of the leaflets; but clearly differs in the short petiole and the transversely dilated rachis of the leaf-stalk. lf we are not mistaken in associating with Hinton’s two flowering collections (nos. 11512, 14915) from Guerrero two in fruit from Oaxaca (M. Sousa 5586, MEXU, from Pochutla; Reko 3699, US, from an unidentified locality), the pod tends to be narrower than that of var. quiedondilla and the areole of the seeds larger, but these characters require confirmation from more complete material.