Senna racemosa var. liebmannii

  • Title

    Senna racemosa var. liebmannii

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna racemosa var. liebmannii (Benth.) H.S.Irwin & Barneby

  • Description

    196e. Senna racemosa (P. Miller) var. liebmannii (Bentham) Irwin & Barneby, stat. nov. Cassia liebmannii Bentham, Trans. Linn. Soc. London 27: 549. 1871.-. . Mexico, prov. Oaxaca. Liebmann."-Lectoholotypus, Liebmann PI. Mex. 5017 = Caesalp. Mex. 41, collected XI. 1842 at Santiago Astata [‘S. Iago Estata’], Oaxaca, C! = NY Neg. 10484; isotypi, C, K! = NY Neg. 1420.-Gaumerocassia liebmannii (Bentham) Britton ex Britton & Rose, N. Amer. Fl. 23(4): 253. 1930.

    Cassia liebmannii sensu Standley, 1922, p. 411.

    Densely pilosulous throughout with fine weak spreading-ascending hairs to 0.4-0.8 mm, the vesture of lvs gray, of inflorescence rusty; lvs (7-)8-16 cm; lfts 6-9 pairs, the largest 2-3.7 x 1-1.7 cm, obovate, elliptic-obovate or -oblong, obtuse or subemarginate mucronulate, the 5-7 pairs of secondary veins immersed above, prominulous beneath, tertiary venulation faintly visible but scarcely raised beneath only; outer sepals 3.5-5.5 mm, inner ones 5.5-8(-9) mm; 4 petals 14-16.5 mm, the odd one 15-18 mm; anthers 3-5.5 mm, the thecae thinly pilose distally with weak hairs to 0.5-0.7 mm; ovary densely pilosulous; style glabrous 2.5-4 mm; body of pod (not well known) 11-19 x ±1 cm, the seed-locules 6-7 mm long.-Collections: 10.

    Brushy hillsides ±600-1200 m, locally plentiful on the Pacific slope of s.-e. Oaxaca in the drainage of rio Tehuantepec (lat. 95°-96°20'W) and apparently disjunct in e.-centr. upland Chiapas (mun. La Trinitaria; mun. Tzimol), Mexico.- Fl. XI-II(-V).

    Between its discovery in 1842 and the publication of Britton & Rose’s revision in 1930 Cassia liebmannii was known only from the type-collection and the nature of its relationship to Senna racemosa (or Cassia ekmaniana) could not be evaluated. Thanks to the collections of Thomas MacDougall in the Isthmus region in the last decade we have a much clearer picture of it and find that it differs from typical S. racemosa chiefly in the pubescent ovary with slightly longer style and in the less prominent venulation of the leaflets. The newly described vars. sororia, coalcomanica and moctezumae, collectively different in the more numerous leaflets, differ among themselves in the same features, the first having the venulation and pistil of var. liebmannii and the other two the glabrous ovary and reticulate mature leaflets of var. racemosa. The morphological discontinuities between the five varieties are of about equal magnitude and would be insignificant unless supported by an emphatically vicariant pattern of dispersal.