Senna paradictyon

  • Title

    Senna paradictyon

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna paradictyon (Vogel) H.S.Irwin & Barneby

  • Description

    160.  Senna paradictyon (Vogel) Irwin & Barneby, comb. nov. Cassia paradictyon Vogel, Syn. Gen. Cass. 45 & Linnaea 11: 686, descr. ampliat. 1837.— "In Brasilia: Sellow leg."—Holotypus, labelled "Sao Paulo," received by Kunth from Humboldt, †B = F Neg. 1724! neoholotypus, Sellow s.n., K! = NY Neg. 1470.

    Cassia paradictyon sensu Bentham, 1870, p. 128, exclus. pl. Martian, e Serro Frio quae = Chamaecrista choriophylla var. latifolia (M!); Bentham, 1871, p. 551.

    Coarse, amply leafy herbs with stout, few-lvd stems procumbent and incurved- ascending from vertical lignescent rootstock up to 3 cm diam, glabrous except for minutely puberulent raceme-axes, the internodes prominently angulate and sulcate by 3 ribs descending from each lf, at anthesis 3-6 dm, the few large plane chartaceous, prominently finely reticulate lfts dull olivaceous subconcolorous, the long-pedunculate racemes arising vertically from lf-axils, in fruit either shorter or a little longer than the lf.

    Stipules erect herbaceous, subsymmetrically ovate obtuse or deltately acumi- nulate 1-3 x 0.7-1.8 cm, many-nerved from base, the sharply prominulous venules branched and anastomosing distally, the blades persistent.

    Lvs 1.5-3 dm; petioles stout (5-)6.5-10 cm, obtusely 5-ribbed, at middle (1.3-)2-3 mm diam, deeply sulcate ventrally; rachis (3-)4.5-14 cm, terminating in a stiff linear or sometimes claviform seta; petiolar glands 0; pulvinules 4-6.5 mm, discolored when dry; lfts (2-)3-5 pairs, accrescent distally, their blades decurrent on the pulvinule at least proximally and appearing sessile or almost so on rachis, the distal pair amply obovate or obovate-flabellate, 6.5-12 x 5-9 cm, 1.2-1.6 times as long as wide, very obtusely rounded or obscurely depressed- deltate-acuminate at apex, the subcentric, slightly incurved midrib immersed above, cariniform beneath, the ±10-16 pairs of camptodrome (with random intercalary) secondary, connecting tertiary and fine reticular venules all sharply prominulous on both faces, the camptodrome arches confluent well within the plane, sharp-edged margin and giving rise toward it to a very fine and dense reticulum.

    Peduncles 7-21 cm; racemes loosely (10-) 15-35-fld, the yellowish glumaceous, prominently multistriate bracts and emergent fl-buds crowded at apex into a narrow cone, the axis early elongating, in fruit 7-21 cm; bracts ovate-elliptic obtuse or deltately subacuminulate 9-14 mm, covering only the very young fl-buds, persistent until just before anthesis; pedicels at and after anthesis 2-3.5 mm, subtended at very base by a pair of narrowly lance-subulate membranous-margined bracteoles 3-5 mm; fl-buds symmetrically lanceolate in profile, obtuse at narrow apex, glabrous; sepals resembling bracts in texture and venulation, scarcely or little graduated, narrowly lanceolate to linear- or lance-elliptic or (the outer) ovate-elliptic, all obtuse, the longest 16-23 x 1.8-4 mm; petals yellow or orange- yellow fading stramineous (not brown-veined), 4 obovate-cuneate, 1 more oblique and crenulate-margined, all of about equal length, the longest 18.5-27 mm; androecium glabrous, functionally 2-merous, the filaments of 4 median and 2 large abaxial stamens 1.8-2.5 mm, of the centric abaxial staminodal stamen 5-6.5 mm, the anthers of 4 median stamens lance-oblong straight, including the short porrect 2-porose beak 5-5.5 mm, those of 2 fertile abaxial ones lanceolate-attenuate, gently incurved from sharply hastate base, 11-14 mm, not beaked but tapering into the terminally minutely 2-porose apex; ovary glabrous or minutely puberulent laterally; style gently incurved, sublinear, 4-6 mm, 0.2-0.3 mm diam; ovules 14-18.

    Pod declined, the stipe 1.5-2 mm, the body oblong-elliptic triangular-acuminate at both ends, piano-compressed 35-47 x 14-19 mm, bicarinate by the scarcely thickened sutures, the stiffly papery, green then pale brown and ± lustrous valves finely transverse-venulose, not at all raised over the seeds, the cavity continuous (vestigial membranes between seeds but no defined locules); dehiscence primarily through the ventral suture, the valves there gaping in age; seeds transverse, pyriform, subemarginate at apex, compressed parallel to the valves, 7.5-8 x 4.8-5 mm, the testa smooth atropurpureous lustrous, the linear-elliptic areole ±5 x 1.2 mm.—Collections: 14.

    Campo, below 400 m, uncommon but locally plentiful in the foothills of the Paraguai and Parana valleys in lat. 20°-26°S, in s. Mato Grosso and (presumably adjoining) Sao Paulo, Brazil and s.-e. Paraguay.—Fl. XI-III.—Suliman (guarani); fedegoso do campo.

    It is by inadvertence that Vogel described in Synopsis Cassiae the leaflets of C. paradictyon as 6-8 pairs, for this is corrected to 6-8 leaflets in the extended description in Linnaea. The epithet paradictyon alludes to the close reticulation around the outer periphery of the leaflets, lying between the margin itself and the camptodrome arches of the major secondary veins.

    According to Balansa, who collected the species near Caaguazu in 1876, the Guaranis prepared a poisonous extract from the foliage.