Senna mandoni

  • Title

    Senna mandoni

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna mandonii (Benth.) H.S.Irwin & Barneby

  • Description

    107.  Senna mandoni (Bentham) Irwin & Barneby, comb. nov. Cassia mandoni Bentham, Trans. Linn. Soc. London 27: 540. 1871.—"Bolivia near Sorata, prov. Larecaja, Mandon, n. 751bis."—Lectoholotypus, collected in valley of R. Challasuyo, VIII-IX.1858 (fl, fr), BM! isotypi, K (hb. Hook., fl absque fr) = NY Neg. 1560, P!

    Cassia subelliptica Rusby, Bull. N.Y. Bot. Gard. 8: 94. 1912.—"[Bolivia:] Sorata, 7500 ft., Sept. 1, 1901 ([.R. S. Williams] No. 2383)."—Holotypus, NY! isotypi, BM, K!

    Cassia cookii Killip & Macbride ex Macbride, Field Mus., Bot. 13(Fl. Peru), pt. 3(1): 160. 1943.— "Cuzco: San Miguel, Urubamba Valley, Cook & Gilbert 1747 . . Holotypus, US! clastotypus (fragm), F!

    Shrubs 2-3 m with gray or castaneous striate or finely canaliculate older branches, glabrous throughout or the pulvinules and dorsal face of lfts and some axes of inflorescence charged with fine or random subappressed-incurved hairs to 0.3-0.7 mm and the ovary often thinly pilosulous, the foliage strongly bicolored, the firmly membranous lfts dull dark green above, pallid and often glaucescent beneath, the racemes mostly subtended by fully developed lvs and at first lateral immersed, at length becoming ± paniculate, the panicle sometimes shortly exserted.

    Stipules erect or spreading, thinly herbaceous, symmetrically linear-lanceolate or lance-acuminate plane 3.5-6 x 0.7-1.7 mm, early deciduous.

    Lvs at least sometimes heteromorphic, those of vigorous main stems (lacking from most spms) longer and ampler than the rest, those of flowering branchlets mostly 4-14 (the lower up to 22) cm; petiole including strongly wrinkled pulvinus (1.7-)2-4.5(-5.5) cm, at middle 0.6-1.1(-1.9) mm diam, narrowly grooved ventrally; rachis 0.7-4(-5.5) cm; pulvinules 0.9-2.2(-2.5) mm; glands (often eaten) between all pairs or all but the distal pair stipitate or subsessile, in profile 1.4-3.5 mm tall, the fusiform acute or obtuse head 0.4-0.8 mm diam; lfts (2-)3-5 pairs, accrescent distally, elliptic-oblong, elliptic or obovate, obtuse mucronulate or minutely emarginate, the distal pair mostly (1.8-)2-6 x (0.7-)0.8-1.7 (or in some lower lvs up to 1.5-3.8) cm, 2-4.2(-4.5) times as long as wide, all at base rounded or semicordate on proximal and cuneate on distal side, the often discolored margin plane (incipiently revolute if dried when young), the venation of upper face immersed, the straight midrib cariniform beneath, there giving rise to 6-10(-13) pairs of fine, weakly prominulous or fully immersed but discolored secondary venules, subsequent venulation 0.

    Racemes loosely 8-35(-60)-fld, the nodding buds usually elevated a little above level of open fls, the axis together with short peduncle becoming (2.5-)4- 17 cm; bracts resembling stipules in texture, lanceolate or narrowly lance-ovate 2.5-5 x 0.4-1 mm, caducous; mature pedicels 13-33 mm; young fl-buds plumply obovoid glabrous; sepals submembranous fuscous-purplish with narrow hyaline margin, obovate or oblong-obovate obtuse, not much graduated, the 2 outer ones 4-6 mm, the longest inner one 6.5-8 mm; petals yellow drying brownish-yellow, delicately dark-veined, glabrous, the vexillary one broadest obovate-flabellate emarginate, the rest oblong-obovate obtuse, the longest 9.5-14.5 mm; androecium glabrous, the 3 staminodes dilated paddle-shaped, the filaments of 4 median stamens 1-1.6 mm, of 2 latero-abaxial ones dilated (3.5-)4-7.5 mm, of the centric abaxial one 1.3-3 mm, the anthers of 4 median stamens 3.2-4.5 mm, of 2 latero- abaxial ones 4.7-6.5 x 1.3-1.6 mm, of the centric abaxial one depauperate 3.3-4.5 x 0.6-0.8 mm, all obliquely truncate, the orifice a little produced into a narrow apron, the orifice divided by slender septum; ovary thinly pilosulous proximally or subglabrous; style 2.5-3 mm, abruptly incurved at tip through at least 300°, not or scarcely dilated, at apex 0.2-0.3 mm diam, the orifice terminal glabrous; ovules 12-25.

    Pod obliquely pendulous, the stipe 3.5-5 mm, the narrowly oblong piano-compressed body 3.5-8 x 1.2-1.6 cm, bicarinate ventrally, simply carinate dorsally, the papery brownish, delicately venulose valves only slightly raised over the seeds, the seed-locules 3-4.5 mm long; seeds (little known) obovoid, 4.4-6.3 x 2.5-3.9 mm, plump or moderately compressed parallel to the valves, obscurely pinched at hilum, the testa brown lustrous, either smooth or coarsely pitted, exareolate.—Collections: 11.

    Rocky hillsides and thickets along streams, 1600-2800 m, apparently local and seldom collected, e. scarp of the Bolivian altiplano on the sources of rios Beni and Mamore in La Paz (prov. Larecaja), Cochabamba (head of rio Ayopaya) and Santa Cruz (prov. Valle), Bolivia, n. to the upper Urubamba valley in Cuzco, Peru.—Fl. V-XI.

    A senna notable for the relatively few, dorsally glaucescent leaflets and glands between all or all but the distal pair. In these features it differs from vicariant or sympatric forms of S. birostris or from S. aymara, both of which have or can have similar perianths and androecia, but a less abruptly incurved style. The perhaps related S. (ser. Coluteoideae) cajamarcae, distantly allopatric in northern Peru, adjoining Ecuador, and western Panama, has similar foliage but broad floral bracts and a narrower, strongly turgid, pluriovulate pod. Senna mandoni is presently known from four small and well separated areas, three in Bolivia and one in Cuzco, Peru; whether it occurs in intermediate stations remains to be seen. The Peruvian populations (C. cookii) have relatively small leaflets pubescent dorsally, in this but apparently in no other respect differing from the Bolivian ones. The plants from Sorata (including typi of S. mandoni and S. sub elliptica) have slightly larger flowers and more heteromorphic leaves than those from Santa Cruz. The seeds of the latter are plump and smooth, while those of the Sorata plant are unknown unless Bang 1985 (NY, sine loc.) is from that region. The seed of Bang 1985 has a deeply and densely pitted testa, the significance of which, if any, cannot be evaluated at present.

    A poor specimen in young flower from Siberia, Cochabamba (Cardenas 5574, K) is suggestive of S. mandoni in habit and coloration of foliage, but differs in the deltately subacute leaflets yellowish-strigulose along the midrib dorsally and minutely ciliolate. Its identity remains doubtful.