Senna pallida var. trichocraspedon (Sandwith) 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.

Family

Caesalpiniaceae

Scientific Name

Senna pallida var. trichocraspedon (Sandwith) H.S.Irwin & Barneby

Type

Holotypus, K! = NY Neg. 1426; isotypi, F, NY! paratypi, Hinton 355, 2972, 5742, all F, K, and all but 355, NY!

Synonyms

Cassia trichocraspedon Sandwith, Cassia tortuosa L.B.Sm. & B.G.Schub.

Description

Variety Description - Slender, ultimately arborescent shrubs at anthesis 1-5 m with terete or faintly ribbed, often abruptly flexuous but stiff branches, either pilosulous throughout with spreading or spreading-incurved hairs up to 0.3-1 mm, the lfts then pubescent on both faces but more densely so beneath, or only the young stems and lf- stalks pilosulous and the lfts then glabrous ciliolate, the inflorescence formed of 1-several, mostly 2-fld racemes pseudofasciculate or shortly racemose on leafless brachyblasts axillary to coeval or lately fallen lvs, some rarely terminal to branchlets. Stipules setiform 1.5-6 mm. Major lvs 7-12.5(-14) cm; petiole (7-) 10-20 mm; rachis (3-)4-8.5 cm; gland between or immediately above first pair of lfts stipitate, including glabrous or hispidulous stipe 3-4 mm, the lance-elliptic body 0.55-0.7 mm diam; sometimes a similar gland between second pair, and the seta similarly modified but more slender; lfts (6-)7-10(-11) pairs, commonly but not always heteromorphic, those of lvs low on the branchlets often proportionately broader and more obtuse than the rest, the majority lance- or oblong-elliptic acute, some oblong-obovate sub- obtuse, always accrescent upward along rachis, the distal pair (2-)2.5-4.5 x 0.6-1.2 cm, ±2-3 times as long as wide, the margins strongly revolute at maturity, the centric midrib with 6-10 pairs of major camptodrome secondary nerves finely prominulous above, sharply and more strongly so beneath, tertiary reticulation 0 or weak and irregular. Peduncles (3-)8-20 mm; pedicels 12-24 mm; long sepals ±6-8 mm; long petals up to 20-28 mm; androecium glabrous, the filaments of 4 median stamens 1.1-1.6 mm, of 3 abaxial ones 2.5-5 mm, the anthers of 4 median stamens 4-5 mm, of 3 abaxial ones 5-7, their beak 2-2.8 mm; ovary ciliate or ciliolate along sutures, glabrous or almost so laterally; style 1.2-1.5 mm; ovules 26-34. Stipe of pod 4.5-9 mm, the body 7.5-13 x 0.6-0.85 cm, the papery valves nigrescent glabrous, the sutures either permanently pilosulous-ciliolate or gla- brescent; seeds 3.4-4.8 x 3-3.7 mm, the areole oblong-elliptic 1-1.7 x 0.5-0.9 mm.-Collections: 9. [Key: "Appendage terminal of lf-stalk modified into a gland resembling that between proximal pair of lfts; local either in highland centr. Costa Rica or in s. Mexico (Mexico, Oaxaca, Veracruz). Lfts of larger lvs 9-12 pairs; ovules 26-52; either the larger lfts over 2 cm long or the pod over 12 cm long. Plants of s. Mexico. Larger lfts 25-60 cm long; ovules ±25-32; pod 7-13 X 0.6-0.85 cm; either Pacific lowland Oaxaca or s. Mexico. Margin of mature lfts strongly revolute; venation of lfts sharply prominulous on upper face; s.-w. Mexico."]

Distribution and Ecology - Oak woods and brushy hillsides in the oak-pine belt, ±1400-1700 m, local in the s. and s.-w. foothills of Volcan Toluca in mun. Temascaltepec, Amatepec, and Almoloya de Alquisiras, Mexico.-Fl. XII-III.

Discussion

In the protologue of C. trichocraspedon Sandwith emphasized as diagnostic features the copious pubescence of the leaves and especially the fringe of hairs persistent along the pod sutures, but he recognized the relationship to Peiranisia palmeri (our S. pallida var. palmeri), very similar in the pod although different in the glabrate, broader and blunter, less venulose leaflets. The pubescence of the typus and several paratypi of C. trichocraspedon, all of which are derived from two localities (Ypericones and Telpintla) about 20 km apart, is indeed peculiar in the group, but the typus of C. tortuosa, which has the same glandiform seta and broad pod as C. trichocraspedon, and which was described from a station immediately contiguous to Cerro de Ypericones, has glabrate ciliolate foliage and only residual cilia along the sutures of the pod. We feel certain that these two are merely aspects of one taxon, the diagnostic value of pubescence being, as elsewhere in ser. Rostratae, illusory. Collectively C. trichocraspedon and C. tortuosa differ significantly from other Mexican forms of S. pallida only in the terminal gland of the leaf-stalk, analogous to that of Costa Rican var. cordillerae, which differs chiefly in its thin-textured, very markedly bicolored, less venulose leaflets and those characters brought out in our varietal key. The highly irregular corolla, thought by Smith & Schubert to distinguish C. tortuosa from other Interglandulosae, is actually, to the contrary, characteristic of the series and in no detail different from the corolla of sympatric C. trichocraspedon.

Distribution

México Mexico North America|