Senna aculeata

  • Title

    Senna aculeata

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

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

  • Description

    157.  Senna aculeata (Bentham) Irwin & Barneby, comb. nov. Cassia aculeata Pohl ex Bentham in Martius, Fl. Bras. 15(2): 128, t. 39. 1870.—". . . in provincia Goyaz prope Curralinho: Pohl; in uliginosis districtus Pa- ranagoa provinciae Piauhy: Gardner n. 2551."—Lectoholotypus (Britton & Rose, 1930, p. 251, by implication): Pohl 120, K! isotypi, NY, W! paratypi, Gardner 2551, BM, FI, NY, W!—Chamaesenna aculeata (Bentham) Pittier, Arb. y Arbust. Legum. II. Cesalpin. 131. 1928. Echinocassia aculeata (Bentham) Britton & Rose, N. Amer. Fl. 23(4): 251. 1930.

    Cassia aculeata sensu Bentham, 1871, p. 551; Pio Correa, Dicc. Pl. Ut. Bras. 2: 587, fig. 1931.

    Coarse prickly diffuse or assurgent shrubs at anthesis 0.6-3 m, with terete purplish-brown stems armed, like the lf-stalks, with scattered straight acicular or deltate-acuminate and laterally compressed, either straight or recurved, vulnerant epidermal prickles up to 2-7 mm, the axis of inflorescence and often the young branchlets, some lf-stalks, and margin of some lfts charged with erect capitately thickened glandular trichomes up to 0.2-0.5 mm, the foliage olivaceous subglaucescent, the stiff subcoriaceous spine-tipped lfts subconcolorous glabrous on both faces, the erect racemes axillary to distal lvs or, by inhibition of the leading shoot, appearing terminal.

    Stipules erect foliaceous broadly ovate acute or acuminate (1.5-)2-6 x (0.8-) 1.2-3.3 cm, at base cordate-amplexicaul, the plane blades many-nerved from base, tardily deciduous.

    Lvs (9-) 12-31 cm, the blades narrowly oblong or oblong-elliptic in outline, the proximal lfts smallest, the rest subequal or slightly decrescent distally; petiole including the discolored but little swollen pulvinus (1-)1.5)-3(-3.5) cm, at middle (1.2-) 1.5-2.5 mm diam, terete except for 2 narrow approximate ventral ridges enclosing the narrow sulcus; rachis 7-22 cm; petiolar gland 0; pulvinules 1-2 mm; lfts 6-14, of lvs subtending peduncles seldom over 9 pairs, oblong- or lance- oblong acuminate, the longest of each lf 2.5-7 x 1-1.8(-2) cm, 2.7-4.2 times as long as wide, at apex contracted into a vulnerant spinule 0.8-2 mm, at base inequilaterally rounded or semicordate, the margin bordered with a thickened pallid, smooth or glandular-verruculose nerve, the subcentric midrib with ±9-14 pairs of camptodrome (and random intercalary) secondary nerves faintly raised above, sharply prominulous beneath, an irregular tertiary-reticular venulation finely prominulous dorsally, invisible above.

    Racemes shortly pedunculate many-fld, before anthesis of first fl taking the form of a clavate cone of petaloid bracts, the axis quickly elongating and elevating the bracteal cone beyond the open fls, at length 1-4 dm; bracts membranous yellow, dorsally capitate-glandular, obovate or oblong- or rhombic-obovate from a broadly cuneate base, 11-22 x 9-14 mm, at apex obtuse or deltately subacute, folded over the young fl-bud, deciduous as the pedicel elongates; pedicels at full anthesis and afterward 8-20 mm; fl-buds obliquely obovoid, at least at base capitate-glandular; sepals membranous petaloid, not much graduated, oblong-obovate or obovate obtuse, the longest 8.5-12.5 mm; petals glabrous, yellow with darker yellow veins, drying whitish brown-veined, the vexillar one oblong or oblong-obovate, the rest ± obliquely obovate, the 2 abaxial slightly longer, the longest petal 13-16 mm; androecium glabrous, functionally 2-merous, the 3 adaxial members staminodal, the anthers of 4 median and one central abaxial stamens greatly reduced and sterile or almost so, the filaments of 4 median stamens 1.5-2.5 mm, of 2 fertile ones thickened and 2-3 mm, of the centric abaxial one filiform 4-4.5 mm, the anthers of 4 median and of the centric abaxial stamens narrowly ovate, shortly porrectly beaked 2.5-4 mm, of the 2 fertile ones lunately lanceolate strongly obcompressed 8.5-10 mm, sagittate at base, contracted at apex into a porrect beak ±0.8-1 mm, this forming an introrsely oriented pollen-cup sometimes divided by a filiform septum; ovary glabrous; style filiform 4-5 mm, gently incurved and 0.2-0.25 mm diam just below the subacute apex; ovules 20-28.

    Pod obliquely ascending, broadly linear-oblong, piano-compressed, 8.5-11 (-12.5) x 1.9-2.7(-3) cm, cuneately contracted at base into a stipe ±3-5 mm, bicarinate by the scarcely thickened sutures, the papery valves fuscous except toward the pallid margins, low-corrugate by simple transverse ridges expressed over the seeds, when ripe separating along both sutures and ± recurved from the ventral side; seed-locules 3-4 mm long, extending transversely almost from suture to suture; seeds transverse, oblong-obovate or obovate, compressed parallel to the valves, 6.3-8.5 x 3-4 mm, the testa brown lustrous, the linear areole 3.8-5.3 x 0.6-0.9 mm.—Collections: 36.

    Annually flooded savannas, pantanal thickets, lagoon margins, becoming weedy in disturbed grassland, wet pastures and on roadsides, 10-500 m, of tri-centric dispersal: locally abundant in scattered stations around the s. edge of Amazon Basin from the upper forks of R. Guapore in e. Bolivia and adjoining Brazil e. to s. Piaui and s.-centr. Goias, thence s. in the Paraguai Basin through Mato Grosso to centr. Paraguay; rio Apure basin in Portuguesa, Barinas, w. Guarico and Apure, Venezuela, very likely naturalized; both cultivated and escaped in w. Cuba (La Habana).—Fl. in Brazil and adjacent countries mostly IV-VIII, in Venezuela IX-I, in Cuba I-III, but governed probably by water supply rather than by season.—Taperiba guaru (Paraguay); Flor de Barinas (Venezuela).