Senna incarnata

  • Title

    Senna incarnata

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna incarnata (Pav. ex Benth.) H.S.Irwin & Barneby

  • Description

    173.  Senna incarnata (Bentham) Irwin & Barneby, comb. nov. Cassia incarnata Pavon ex Bentham, Trans. Linn. Soc. London 27: 545. 1871.-"Tropical America: Peru . . . Pav! in herb. Lamb, nunc Mus. Brit. . . . and Bolivia."-Holotypus, ticketed by Pavon "Cassia incarnata sp. nov. de Mexico" BM! - NY Neg. 110; isotypi, labelled ‘in collibus Pachacana [=Pachacamac], MA (hb. Pavon. 1418) and s. loc. FI! and "Perou, misit Pavon 1827," G (hb. Moricand.)! = F Neg. (+ fragm) 28006.

    Cassia versicolor sensu Bentham, PI. Hartweg. 128 [Hartweg 729 from Malacatos, Ecuador, K! = NY Neg. 1562]. 1843; non Meyen ex Vogel, 1837.

    Cassia incarnata sensu Macbride, 1943, p. 169.

    Shrubs, either erect and finally arborescent or diffuse and bushy, at anthesis 0.5-5 m, the angulately ribbed, finally brown and lenticellate branchlets and the lf-stalks thinly or densely either pilosulous with spreading or strigulose with sub- appressed weak shining hairs to 0.2-0.8 mm, these mixed with random short thickened livid ones, the firm dull olivaceous subconcolorous lfts above glabrous, beneath varying from densely pilosulous to glabrous except for ciliolate midrib, the inflorescence of subumbellate racemes axillary to normal or distally reduced foliage, not or shortly exserted.

    Stipules linear-elliptic attenuate at both ends (4-)5-15 x (0.5-)0.8-2.5 mm, at base divergent from pulvinus across the stem, thence falcately or subsigmoidally incurved to erect, the firm herbaceous blades early dry brunnescent, deciduous long before lf.

    Lvs below inflorescence (4-)5-14 cm; petiole including little dilated pulvinus (10-) 12-25 mm, at middle 0.5-1.2 mm diam, bluntly 3-ribbed latero-dorsally, openly shallowly sulcate ventrally; rachis (3-)3.5-11.5 cm; gland 1 sessile or shortly stipitate between proximal pair of lfts (1-) 1.8-3.6 mm, the stipe when present either glabrous or puberulent, the livid glabrous body narrowly fusiform to obliquely rhombic acute, when broad laterally compressed; lfts (6-)7-14(- 17) pairs, of almost equal size or commonly a little decrescent both up- and downward from near middle, ascending from rachis face upward on scarcely dilated pulvinule (0.5-)0.7-1.1(-1.4) mm, in outline oblong-elliptic to elliptic-obovate obtuse mucronulate or deltately subacute, those (largest) near middle of rachis (9-) 11- 24 x 3.5-8.5 mm, 2.2-4 times as long as wide, at base asymmetrically rounded or subcordate, the margin plane, the centric midrib cariniform beneath, the venation otherwise immersed or 5-8 pairs of secondary camptodrome venules faintly raised beneath.

    Peduncles 1.5-5 cm; racemes subumbellately or very shortly (3-)4-8(-9)-fld, the axis becoming 1.5-5(-7) mm; bracts obovate or oblanceolate cucullate 1.5-4.5 mm, caducous; pedicels 16-27 mm, the lower ones subtended laterally by an early divergent or deflexed stipitate gland 2-5 mm, this sometimes rudimentary or 0; fl-buds globose, glabrous above immediate base; sepals submembranous greenish with petaloid margins, faintly nerved, strongly graduated, all broadly obovate-suborbicular but the outer scarcely half as long as the innermost, these 7-10 mm; petals yellow, glabrous or dorsally puberulent near claw, 3 adaxial shorter and narrower, oblong- or obovate-oblanceolate beyond the short claw, the 2 abaxial longer, one subsymmetrically obovate, the other boomerang-shaped 15.5-21 mm, its blade nidulating the longest stamen; androecium glabrous but the anthers granular-papillose, the filaments of 4 median stamens 1-1.4 mm, of 2 abaxial ones 2-3.5 mm, of one abaxial one 3-5.5 mm, the anthers of 4 median stamens oblong, slightly incurved 2.7-3.8 mm, with lateral biporose beak scarcely 0.4 mm, the anthers of 3 abaxial lunately incurved, the body 3.2-4.5 mm, the tubular beak 1.2-1.6 mm, dehiscent by a pore usually interrupted by a slender septum; ovary canescently strigose-pilosulous, the glabrate style linear sometimes slightly enlarged upward 1.8-3.5 x 0.2-0.35 mm; ovules 20-28.

    Pod erratically pendulous, the stipe 5-7 mm, the linear straight ribbon-like body 6.5-11 x 0.45-0.65 cm, the papery fuscous continuous valves pallid along the sutures, elevated over each seed as a low-convex or low-pyramidal mound; seeds fuscous or brownish, oblong- or rhombic-obovoid (2.3-)3.1-3.9 x (1.4-)2.2-2.7 mm, the testa moderately lustrous crackled, the elliptic areole (0.8-)0.9-1.3 x 0.5-0.9 mm.-Collections: 31.

    Brushy and stony hillsides and rocky bluffs, 1500-2800 m, sometimes forming thickets in overgrazed pasture or in hedges, locally abundant in widely separated stations along the crest and Pacific slope of the Andes in Ecuador (Chimborazo; Loxa) and Peru (Cajamarca; Ancash; Lima), between 2° 15' and 12°S, in Lima descending locally (at Atocongo) to the foothills (loma formation) at 300-400 m.- Fl. almost throughout the year.

    Senna incarnata is readily distinguished from other Andean Interglandulosae by its falcate stipules and umbelliform racemes of about 4-8 flowers, these contrasting with the mostly 2-flowered racemes of S. pallida sens. lat. All superficially similar sympatric sennas lack stipitate glands at base of the pedicels and have truncate, not tubular-beaked long anthers. This is a clearly differentiated, little variable and seldom misidentified species.