Senna mutisiana (Kunth) 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 mutisiana (Kunth) H.S.Irwin & Barneby

Type

Holotypus, B (not seen) = F Neg. 1713! isotypi, P-HBK! P (hb. Bonpland.)!—Peiranisia mutisiana (Kunth) Pittier, Bol. Ministerio RR. EE. 1-3 (Arb. Arbust. Legum.): 128. 1928.

Synonyms

Cassia mutisiana Kunth, Peiranisia mutisiana Pittier

Description

Species Description - Shrubs at anthesis 1.5-3 m with densely leafy, distally ribbed annotinous branchlets, these with lf-stalks and often the foliage pilosulous in varying density with spreading or incumbent, commonly lutescent hairs up to (0.2-)0.3-0.6(-0.7) mm, the subconcolorous lfts pilosulous on both faces or only beneath, then sometimes merely at one basal angle of midrib, sometimes glabrous except for ciliolate margins, the stems in addition nearly always hispid with horizontally spreading pale or yellowish shining setae up to (3-)4-9 mm (these exceptionally quite lacking), the inflorescence of short but loosely several-fld racemes at first axillary to long coeval lvs and immersed, sometimes by reduction or atrophy of distal lvs becoming corymbose and exserted. Stipules herbaceous, falcately lance-attenuate or unilaterally dilated and then semi-ovate-acuminate, 4-14 x 0.5-4.5 mm, deciduous before associated lf. Lvs (below the panicle, where often much reduced) 6-17 cm; petiole including moderately thickened pulvinus 4-11 mm, at middle 0.6-1.5 mm, narrowly thick- margined and grooved ventrally; rachis 5-15.5 cm, the ventral wings constricted at each pair of pulvinules; glands between proximal 1-3 pairs of lfts subsessile or stipitate 1-3 mm, the fusiform acute body 0.3-0.7 mm diam, shorter spiculiform glands between all other pairs; pulvinules 0.3-0.5(-0.8) mm; lfts (25-)30-52 pairs inserted on rachis 1.5-3.5(-4.5) mm apart, very gradually decrescent both up- and downward from a point below middle of rachis, the larger ones in outline oblong or lance-oblong from asymmetrical base, obtuse mucronulate or sub- emarginate, 6-13 x 1.6-4 mm, dorsally carinate by the midrib, the margins (at least proximally) revolute, the venation other than costa immersed. Peduncles 1.5-5 cm; racemes 5-9-fld, the axis 8-23 mm; bracts submembranous lance-elliptic cymbiform 2.5-4 mm, caducous; pedicels 13-28 mm, a fusiform stipitate gland beside each; buds globose glabrous or puberulent at base; sepals very unequal, the small outer ones firm, the inner subpetaloid, broadly obovate- suborbicular 8.5-11 mm; petals glabrous, 4 subequiform obovate beyond the narrow claw, the fifth obliquely or falcately oblanceolate, the longest 16-20 mm; androecium glabrous, the filaments of 4 median and 1 or 2 of the 3 abaxial ones 0.5-1.5 mm, that of 1 or 2 abaxial ones 2-4 mm, the anthers of 4 median stamens 3.3-5.2 mm subtruncately rounded at apex, the very short beak lateral 2-pored, those of 3 abaxial 3.2-5 mm, gently contracted to a very short erect 2-porose beak 0.35-0.5 mm; ovary thinly pilosulous; style 2-3.5 mm, at incurved apex 0.3-0.35 mm diam; ovules 20-30. Pods randomly ascending or pendulous, the stipe 3.5-5 mm, the flat body (5-)7-10.5 x 0.7-1.05 cm, the thinly papery valves castaneous nigrescent glabrate, the interseminal septa 4-5 mm apart; seeds broadly or narrowly com- pressed-obovoid 4.5-5 x 2.4-3.7 mm, the testa dull brown, the obovate or elliptic-obovate areole 2.2-3 x 1.2-1.7 mm.—Collections: 17.

Distribution and Ecology - Open hillsides and forest margins, 900-2260 m, scattered along the Eastern Cordillera of the Colombian Andes from Huila n. to Norte de Santander and thence n.-e. to Cordillera de Merida in Venezuela, lat. 3°-8°30'N.—Fl. I-VIII, perhaps intermittently through the year.

Discussion

Senna mutisiana is usually strongly characterized by the coincidence of lustrously setose stems with narrow multifoliolate leaves, glands at base of pedicels slender pod, features all apparent in Turpin’s exquisite colored engraving in Kunth’s Mimoses. The species is closely related to northwardly vicariant S. williamsii, but sufficiently different in its short proper petioles, looser racemes of somewhat smaller flowers, short-beaked anthers and broader pods that accommodate larger seeds in wider locules. The setose indumentum of the stems, so striking to the eye in both these species, is here as elsewhere in Cassieae an unreliable character. One of the several collections of S. mutisiana known from Cordillera de Merida in Venezuela (Lopez-Figueiras & Rodriguez 9078) lacks it entirely and superficially resembles some microphyllous race of S. multijuga; and Pittier encountered in Chiriquf, Panama forms of S. williamsii growing close together, one with (no. 5407) and one without (no. 5406) cauline setae.

Distribution

Huila Colombia South America| Norte de Santander Colombia South America| Venezuela South America|