Monographs Details: Senna punoënsis Lass.
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.
Description:Species Description - Potentially arborescent to 6 m but probably flowering when smaller and only shrubby, the annotinous branches castaneous, the hornotinous, densely leafy ones with lf-stalks and dorsal face of lfts either strigulose with straight subap- pressed or pilosulous with loosely spreading-ascending hairs up to 0.2-0.45(-0.75) mm, the vesture commonly lutescent, the ample crowded foliage strongly bicolored, the lfts dull olivaceous or dark green and glabrous above, pallid beneath, the axillary racemes equalling or shorter than the subtending lf, forming an immersed or scarcely emergent corymbiform panicle.
Stipules erect submembranous, pallid or brownish, linear-lanceolate 2.5-7.5 x 0.4-1.2 mm, early caducous, absent from mature spms.
Lvs (7-)8-15.5 cm; petiole including discolored but little swollen pulvinus 7-15(-18) mm, not or little longer than the first interfoliolar segment of rachis, at middle 1-1.4 mm diam, the shallow open ventral sulcus narrowly thick-margined; rachis 5.5-10.5 cm, its longer segments 8-14 mm; glands between most pairs or all except the distal pair of lfts, sessile or substipitate 0.8-1.3 mm, the ovoid obtuse or apiculate body of the proximal one 0.3-0.7 mm diam, that of distal ones sometimes much smaller; pulvinules 1-1.4 mm; lfts 7-11 pairs, basipetally decrescent in the lower 1/3 of rachis, subequal distally, in outline narrowly ovate or lance-elliptic acute or obtuse mucronulate, the longest 2.2-3.5 x 0.5-1.2 cm, 3-3.8(-4.5) times as long as wide, at base asymmetrically rounded or proximally cordate, the margin strongly revolute, the midrib cariniform beneath, deeply canaliculate above, the ±8-10 pairs of slender camptodrome secondary veins faintly raised above, discolored but scarcely prominulous beneath, tertiary venulation not or scarcely perceptible.
Racemes ±5-30-flowered, the expanded fls elevated nearly or quite to level of the ascending, obtusely obovoid-ellipsoid, proximally puberulent buds, the axis and peduncle together 3-13 cm; bract resembling stipules in shape and texture 3.5-5.5 mm, caducous before anthesis; mature pedicels 23-33 mm; hypanthium broadly obconic; sepals submembranous fuscous with paler margins, well graduated, all obovate obtuse, the outermost 3.5-5.5 mm, the innermost 8-10.5 mm; corolla zygomorphic glabrous, yellow drying brownish-stramineous brown- veined, the obovate-flabellate emarginate vexillary and 2 similar lateral petals 14.5-17 mm, the 2 elliptic-oblanceolate abaxial ones as long or slightly shorter; androecium glabrous, the blade of staminodes obtusely pentagonal or subquadrate emarginate 1.5 x 0.8-1.4 mm; filaments of 4 median stamens and of the sterile centric abaxial one 3-3.5 mm, those of 2 latero-abaxial ones (3.5-)4-6.5 mm, the anthers brown, those of 4 median stamens straight or nearly so, obliquely truncate 3.5-4.6 x ±1 mm, that of the centric sterile one 3-3.5 x 0.4-0.6 mm, those of the 2 latero-abaxial ones shallowly lunate 5.5-6.5 x 1.2-1.5 mm, at apex horizontally truncate and essentially beakless, dehiscent by a coarsely U-shaped slit; ovary laterally strigulose or thinly pilosulous; style stoutly linear, gently incurved 2-3.5 x 0.3 mm, the minute stigmatic cavity terminal; ovules 42-47.
Pod declined, the stout stipe 4-7 mm, the linear body ±9-12 x 0.8-0.9 cm, a little laterally compressed but strongly turgid, the ripe valves stiffly papery brown; seeds uniseriate, turned broadside to the septa, plumply obovoid ±4.5-5.5 x 3.5-4 mm, the testa lustrous dark brown crackled exareolate.— Collections: 7.
Distribution and Ecology - Open rocky slopes and stream banks at ±2200-2500 m, apparently local on the sources of rfos Madre de Dios and Mamore in n.-e. Puno, Peru (prov. Sandia) and Cochabamba, Bolivia (prov. Sacaba).—Fl. VII-X, IV-V, perhaps throughout the year.
Discussion:This relatively rare and still imperfectly known senna is closely related to S. multiglandulosa, which it resembles in habit, inflorescence and pod. The slightly more numerous lance-ovate rather than oblong-elliptic leaflets glabrous above and only thinly puberulent or thinly pilosulous (not lanate) beneath contribute to a subtly individual aspect, and the horizontally truncate long anthers flanking a sterile centric one provide an apparently reliable technical character in the flower. Senna burkartiana, which ranges southward along the Andes from Cochabamba, is more easily distinguished by the fewer larger leaflets with secondary venation deeply engraved on the upper face.
This species was independently recognized as undescribed by Dr. Alex Lasseigne, now at Nichols State University, Thibodaux, La., during work on his doctoral thesis, and by us in our general studies of Senna. By arrangement with Dr. Lasseigne we are here publishing it as new, but transferring his manuscript epithet to the genus Senna.
Puno Peru South America
| Cochabamba Bolivia South America