Monographs Details: Senna pallida var. triquetripes H.S.Irwin & Barneby
Authors:Howard S. Irwin, Rupert C. Barneby
Authority: Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 2: 455-918.
Description:Variety Description - 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. [Key: "Appendage terminal of lf-stalk subulate or setiform, not modified and dilated into a gland; range of whole species. Continental N. and S. America and Lesser Antilles, s. Windward Is. and Swan Is. in s. Caribbean; anthers nearly always stouter (1.2-)1.3-2 mm diam, abruptly truncate at apex and the tubules there commonly umbonate at the angle opposed to the laterally divaricate, often slightly infra-terminal beak, if whole anther less than 1.25 mm diam and umbo pronounced. Reticulate tertiary venulation imperceptible or almost so on both faces of lfts, these superficially either penninerved or veinless. Lfts of primary lvs 9+ pairs, at least in larger lvs (caveat: deciduous, and absent from some specimens with ample panicle which may be accompanied by only diminished distal lvs), the pairs not or scarcely accrescent upward, the terminal pair not obviously the largest; areole of seeds mostly 1.1-2.4(-3.5) mm in greatest diam. Lfts of largest lvs 9-15(-17) pairs (if led hither by plants of lowland s.-e. Mexico, cf. 177b. var. isthmica). Lf-stalk sharply carnate dorsally and conspicuously green-winged latero-ventrally, the wings constricted at insertion of lfts; where sympatric with the next, the petioles 6-15 mm; local in s. Guerrero and s. Oaxaca."]

Distribution and Ecology - 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.

Discussion: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.
Distribution:Guerrero Mexico North America| Oaxaca Mexico North America|