Senna saeri

  • Title

    Senna saeri

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna saeri (Britton & Rose ex Pittier) H.S.Irwin & Barneby

  • Description

    171.  Senna saeri (Pittier) Irwin & Barneby, comb, nov., Peiranisia saeri Britton & Rose ex Pittier, Bol. Ministerio RR. EE. 1-3: 129. 1928.-". . . Venezuela . . .," but no collection cited.-Lectoholotypus, J. Saer 8, collected "on shores of La Ruesca, Barquisimeto, Lara, Venezuela, VIII. 1923" (fl), NY (annotated by Britton as "cotype")! isotypi, US (2 sheets)!

    Shrubs of bushy outline, at anthesis 1.5-4 m, with purplish-brown, in age pallid- lenticellate branchlets, densely pilosulous throughout with fine spreading-incurved sordid gray or brunnescent hairs up to 0.2-0.45 mm mixed with minute reddish or orange thickened but eglandular ones, the foliage bicolored, the lfts dull brownish-olivaceous and papillate above, paler beneath, the inflorescence of few-, rarely mostly 2-fld racemes at first axillary to and ± immersed in foliage, distally becoming corymbose-paniculate.

    Stipules incurved-erect, linear-lanceolate or subulate 2-6 mm, firm but early caducous.

    Lvs (disregarding depauperate distal ones) 5-11.5 cm; petiole including the livid, moderately dilated pulvinus 1.1-2.3 cm, at middle 0.45-1 mm diam, rounded dorsally, narrowly grooved ventrally; rachis 2-5 cm; petiolar glands (caveat: much eaten) between all pairs of lfts, stipitiate or subsessile, in profile (1-) 1.2-2.2 mm, the stipe puberulent, the livid glabrous laterally compressed acute body 0.3-0.6 mm diam; lfts (3-)4-6 pairs, strongly accrescent upward, ascending face up on terete, moderately swollen pulvinule 0.9-2.4 mm, the distal pair obovate, elliptic-obovate, -oblanceolate, or elliptic, obtuse mucronulate, shallowly emar- ginate or subacute, (20-)23-46 x (7-) 10-19 mm, ± 1.8-3.1 times longer than wide, at asymmetric base rounded on proximal and either rounded or cuneate on distal side, the margin revolute, the straight centric midrib narrowly canaliculate on ventral and cariniform on dorsal face, the 6-10 pairs of major camptodrome secondary with subsequent reticulate venulation always finely sharply prominulous beneath, less so or almost immersed above; proximal lfts progressively smaller downward along rachis and usually proportionately broader and somewhat fewer- veined.

    Peduncles 1-3.5 cm; racemes 2-7 (but seldom all exactly 2)-fld, the fls often subumbellately clustered or pseudoverticellate, the axis (0-) 1.5- 12 mm; bracts broadly oblanceolate concave 2-8.5 mm, covering the young fl-buds, promptly caducous; a stipitate gland (often eaten) beside each pedicel; pedicels 17-30 mm; fl-buds subglobose, either glabrous or proximally puberulent; sepals greenish or brownish with pallid margins, ovate- or obovate-suborbicular obtuse, strongly graduated, the outermost not over half as long as the innermost, these delicately several-nerved from base, 5.2-6.7 mm; petals yellow, puberulent dorsally, 3 adaxial relatively small and long-clawed, oblance-obovate, the 2 abaxial larger, one short-clawed and ovate-cordate, the other obliquely reniform-scoop-shaped, the longer one 1.6-2.4 cm; androecium functionally 7-merous, the filaments thinly puberulent, those of 4 median stamens 0.8-1.6 mm, of 3 abaxial ones 1.8-3 mm, the anthers glabrous or exceptionally puberulent, of 4 median stamens gently incurved 3.3-4.6 mm, the infraterminal beak scarcely 0.3 mm dehiscent by a single U-shaped slit, those of 3 abaxial ones more strongly incurved, the body 3.7-5.5 mm, contracted into an erect tubular beak (2-)2.3-3.3 mm, this slightly enlarged and 1-porose at apex; ovary densely yellowish-strigulose; style 0.9-1.5 mm, not dilated distally 0.25-0.4 mm diam; ovules ±25.

    Pod spreading and pendulous (from obliquely geotropic branchlets appearing erect), the stipe 4-7 mm, the linear, strongly compressed, straight or irregularly decurved body 6.5-15.5 x 0.45-0.6 cm, bluntly 2-carinate by the sutures, the papery atro-castaneous coarsely transverse-venulose valves bullately elevated between septa, the sinuous pallid venulation superficial and elevated, finally detached from the epicarp, the truly ripe valves apparently fracturing along the lines of septation, hence not truly dehiscent; seeds (few seen) paddle-shaped, 2.5-3.7 x 2.2-3 mm, the pale brown, scarcely lustrous testa cross-crackled, bearing on each face an elliptic areole 1.2-1.5 x 0.5-0.6 mm.-Collections: 21.

    Dwarf, drought-decidous scrub-woodland of dry hillsides and valley floors, 450-900(-1450) m, sometimes forming extensive thickets, locally plentiful about the sources of Rios Tocuyo and Yaracuy in Lara and (perhaps disjunct) in Parque Nac. Rancho Grande in n. Aragua, Venezuela.-Fl. II-V, VII-XI, the full range unknown.-Plantanico.

    Senna saeri is closely akin to S. robiniifolia, within the range of which it occupies a restricted enclave. It is a shrub or treelet smaller at maturity than S. robiniifolia; its leaves are mostly shorter, its pairs of leaflets one or two fewer, and its racemes have on the average slightly more numerous flowers. The latter differ only to the extent that the beak of the long anthers tends to be more pronounced. The two species are difficult to distinguish at anthesis, but the sharply raised venulation of the pod of A. saeri, which stands out pallid against a dark ground and becomes detached from it in age, is characteristic.