Senna acuparata H.S.Irwin & Barneby
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Authors
Howard S. Irwin, Rupert C. Barneby
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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.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Holotypus, NY; isotypus, US.
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Description
Species Description - Slender herbaceous vines of unknown stature, with terete striate branchlets, finely pilosulous with spreading-incurved filiform and scattered minute thickened resinous hairs, the former up to 0.25 mm, the foliage dull olivaceous concolorous, the chartaceous, intricately reticulate lfts glabrous above, pilosulous beneath, the inflorescence a weakly ramified panicle of 2-3 short few-fld racemes shortly exserted from foliage, the plant remarkable among Bacillares for the undulate- denticulate leaflet-margin and the absence (possibly only fortuitous on the few specimens seen) of the proximal pair of lfts and the (presumably characteristic) reflexed persistent seta terminating the lf-stalk. Stipules erect linear-attenuate 4-6.5 x ±0.4 mm deciduous. Lvs 10-16 cm; petiole proper (measured from pulvinus to petiolar gland) 10-17 mm, at middle 0.9-1.1 mm diam, rounded dorsally, flattened and shallowly open- sulcate ventrally; rachis 17-33 mm, longer than petiole, produced into a backwardly refracted indurated hooklike seta 3.5-4.5 mm; gland 1 below middle of naked lf-stalk, shortly stipitate, obtusely claviform 1.8-2.7 mm, glabrous; distal (only) pair of lfts ovate-acuminate 7-11.5 x 3.5-5.3 cm, ± twice longer than wide, the slender acumen ±1.5-2 cm and acute at very apex, the blade at base rounded on proximal and broadly cuneate on distal side, the margin plane, irregularly low-sinuate-denticulate, the almost straight centric midrib above canaliculate in lower half thence immersed, beneath prominent cariniform, the ±10-14 pairs of major camptodrome with some intercalary secondary veins and the tertiary and reticular venules all sharply prominulous on both faces, the ultimate defined areoles much less than 1 mm diam. Racemes ±7-14-fld, the axis including short peduncle 1.5-3 cm; bracts lanceolate 3-3.5 mm, tardily deciduous; pedicels becoming 3-3.5 cm; sepals (seen only marcescent) oblong-obovate obtuse moderately graduated, the longer inner ones ±9 mm, delicately 5-6-nerved from base; fl otherwise unknown; ovary strigulose; style scarcely swollen, ±0.7 mm diam; ovules ±52. Pod (not seen fully ripe) stoutly short-stipitate, the stipe 4-6 mm, the body ±6-7 x 0.7 cm, its compression not interpretable from the material seen, the apparently fleshy valves nigrescent; seeds 2-seriate, not seen ripe.—Collection: 1.—Fig. 20.
Distribution and Ecology - Habitat scarcely known, to be sought along forest margins or in disturbed thickets near 100-130 m along the upper Amazon River, known only from the type-station near Iquitos, in Loreto, Peru.—Fl. X.
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Discussion
A remarkable senna with which we have as yet only tantalizingly imperfect acquaintance, but clearly distinct from all described Bacillares in the subsymmetrically ovate-acuminate, undulate-denticulate leaflets combined with stiffly persistent hooked seta terminating the leafstalk. All leaves of the material seen are bifoliolate, and it is a question whether or not a proximal pair may occur in some leaves at the normal site on the leafstalk here marked only by the stipitate gland. The two other Bacillares characterized by hooked or pronged seta that appear modified as grappling-hooks, S. uncata and S. cornigera, differ substantially from S. acuparata in habit and technical characters, especially in the obtuse or only obscurely and obtusely acuminate, entire-margined leaflets. Whereas S. acuparata was seen by the collectors as an herbaceous vine, S. uncata is arborescent and S. cornigera a vigorous liana climbing into high forest canopy. The seta of S. cornigera is not hooked backward but sigmoidally divaricate; the petiole proper is almost none, the leaf-margin is revolute and the pod a long ribbon, up to 2 (not less than 1) dm long. The seta of S. uncata is that of S. acuparata, but its paniculate exserted inflorescence of much longer racemes, the leaflet outline and venulation, and the montane Andean habitat are decisively different. The type collection of S. acuparata was referred by Macbride (l.c.) to Cassia hoffmannseggii auct. (=our S. georgica var. georgica); this, not known to occur in the upper Amazon valley, has distal leaflets of similar outline but differs in the deciduous seta, the constantly 4-foliolate leaves, a larger calyx (long sepals 12-20, not 9 mm), and a slender compressed elongate pod like that of S. cornigera.
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Distribution
Loreto Peru South America|