Senna lasseigneana 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 1: 1-454.

  • Family

    Caesalpiniaceae

  • Scientific Name

    Senna lasseigneana H.S.Irwin & Barneby

  • Type

    Typus infra sub var. lasseigniana indicatur.

  • Synonyms

    Cassia santanderensis var. parvianthera Lass.

  • Description

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    Species Description - Resembling S. santanderensis in habit, but generally smaller-lvd, the lfts puberulent on upper face, variably pilosulous beneath. Stipules submembranous reflexed lanceolate plane 3.5-6 x 1-2 mm, deciduous. Longer lvs 6-11.5 cm; petiole 5-14 mm; rachis 3-7.5 cm; gland ovoid acute 1-1.8 x 0.4-0.8 mm; lfts 4-7 pairs, the terminal pair elliptic 2.5-5 x 0.9-1.8 cm, the venation as in S. santanderensis but the major camptodrome secondary nerves 5-8 pairs. Peduncle with axis of raceme 4-6 cm; bracts lanceolate or ovate-acuminulate 3-6 x 1-3.5 mm; outer sepals 3-4.5 mm, the longest inner one 5-7; longest petal 10-13 mm; filaments of 4 median anthers 2-3, of 3 abaxial ones 3-5 mm (that of centric one a trifle shorter than its neighbors), the anthers of 4 median stamens 3.7-4 x 1.1 mm, of 3 abaxial ones 4.2-6.3 x 1-1.4 mm, the centric one sometimes a trifle shorter than its neighbors but fertile and of the same diam; style 3.5-4 x 0.2 mm, straight or almost so; ovules 22-26. Pod of S. santanderensis, the body (4.5-)5-8 x (0.9-) 1-1.4 cm.

    Variety Key - Key to the Varieties of S. lasseigniana 1. Lfts 4-5 pairs, the lower face thinly pilosulous and beset between the veins with thickened glandiform trichomes; n. Peru. 113a. var. lasseigniana (p. 354). 1. Lfts 5-7 pairs, the lower face densely velutinous-pilosulous both on and between veins with erect lustrous'hairs, lacking glandiform trichomes; s. Ecuador. 113b. var. canarensis (p. 354).

  • Discussion

    This species is coextensive with two varieties of Cassia santanderensis recently described by Lasseigne. In its protologue each was compared with C. santanderensis, but not directly one with the other, and the resemblance between them in many critical points was consequently underemphasized. While they do indeed resemble S. santanderensis in general habit and especially in the pod and the long narrow seeds, they differ collectively in stipules, calyx and androecium, and these differences, supported by the facts of dispersal insofar as known today, seem to us of specific importance. The close relationship of S. lasseigniana seems to lie in the direction of the sympatric S. multiglandulosa from which it is distinguished principally by the shorter broader pod containing fewer but longer and proportionately narrower seeds. But these differences will require the test of experience as material accumulates, as will the weak contrasts between the two varieties expressed in the key following.