Senna brongniartii

  • Title

    Senna brongniartii

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna brongniartii (Gaudich.) H.S.Irwin & Barneby

  • Description

    102.  Senna brongniartii (Gaudichaud) Irwin & Barneby, comb. nov. Cassia brongniartii Gaudichaud, Voy. Bonite, Bot., Atlas t. 10. 1841 & (auct. d’Alleizette) Explic. Planches 59. 1866.—No locality recorded.—Holotypus, collected by Gaudichaud VII. 1836 (fl, fr) at Cobija, Antofagasta, Chile, P! isotypus, G!

    Cassia (?) misera Philippi, Florula Atacam. 17. 1860.—"Una cum priori inveni" i.e. "In valle Guanillo prope Paposa [near 25°S lat. in Antofagasta, Chile] ad c. 2500 p. s. m."—Holotypus, SGO (cf. Munoz Pizarro, 1960, p. 73), not seen but description decisive and already equated with C. brongniartii by I. Johnston, 1929, l.c. infra.—C. misera Philippi, Linnaea 33: 60, descr. secus pl cultam perfecta. 1864.—Overlooked by Bentham, 1871.

    Cassia conjugata Ruiz & Pavon ex Bentham, Trans. Linn. Soc. London 27: 540. 1871.—"Peru, Ruiz and Pavon in herb. Lambert now British Museum; Cobija, Gaudichaud."—Holotypus, BM! = NY Neg. 166; the paratypus, Gaudichaud s.n. = holotypus of C. brongniartii, q. v. supra; isotypi (ex hb. Pavon.), FI (hb. Webb.), G, MA (hb. Pavon. 14/14), P!

    Cassia misera sensu Reiche, 1897, p. 35.

    Cassia brongniartii sensu I. Johnston, Contrib. Gray Herb., new ser. 85: 47, 149. 1929.

    Cassia conjugata sensu Macbride, 1943, p. 160.

    Small microphyllous, ephemerally green subshrub or shrublet, precociously flowering as a tap-rooted herb but in age developing a twiggy blackish caudex giving rise to incurved-ascending leafy stems, at anthesis 1.5-5 dm becoming wider than tall, appearing glabrous but the smooth terete annotinous branchlets, the axillary buds, the lf-stalks and dorsal face of lfts (or some of them) puberulent with fine appressed or incurved whitish hairs up to 0.3-0.5 mm, the subcarno- sulous lfts bicolored, olivaceous above, darker green beneath, the inflorescence composed of axillary and lateral few-fld racemes.

    Stipules erect submembranous flaccid subulate or filiform 0.6-2.6 mm caducous.

    Lvs mostly 2.5-5 cm (some smaller borne on axillary spurs not further mentioned); lf-stalk 13-33 mm, either longer or shorter than the 1 pair of lfts, at middle 0.4-0.8 mm diam, terete except for very narrow ventral groove; gland between the lfts, stipitate or subsessile, in profile 0.6-2 mm tall, the subuli- or slenderly fusiform acute body 0.15-0.4 mm diam; pulvinules 0.8-1.6 mm; lfts broadly or narrowly obovate or elliptic-obovate obtuse or obscurely emarginate, sometimes minutely apiculate 11-24 x 5-15 mm, ±1.6-2 times as long as wide, at base inequilaterally rounded or broadly cuneate, the membranous, when fresh orange-tinged margin plane, the blades veinless on upper face, the lower face carinate by the weakly prominulous centric midrib and faintly penniveined with 3-5 pairs of incompletely camptodrome secondary veins.

    Racemes loosly 2-3-fld, the axis including slender ascending peduncle 1.5-3.5 cm; bracts linear-lanceolate 1.2-2 mm caducous; mature pedicels 10-15 mm; fl-buds subglobose glabrous; sepals petaloid yellow or brown-tinged, obovate or oblong-obovate, moderately graduated, the outermost 4.5-7 mm, the longest inner one 7-10.5(-12) mm; petals orange-yellow, drying pale yellow brown-veined, all glabrous, the 3 abaxial ones obovate beyond the claw, obtuse or emarginate, the 2 abaxial a little narrower but hardly or not longer, the longest petal 12.5-17 mm; androecium glabrous, functionally 6-merous, the 3 adaxial staminodes either oblong emarginate or obcordate 0.6-1 mm, 1-2 of them sometimes transitional in form to adjoining stamens; filaments of 4 median stamens 2-3.5 mm, of 2 latero- abaxial ones 2.5-4.5 mm, the centric abaxial stamen 0, the anthers of 4 median stamens 3-4.2 x 0.8-1 mm, of 2 abaxial ones 4.7-7.5 x 1.2-1.5 mm, very gently and shallowly incurved, all anthers obliquely truncate and dehiscent by short slits separated by a shallow notch; ovary pilosulous; ovules 10-16; style filiform, gently incurved 2.5-3.3 x ±0.2 mm.

    Pod divaricate from ascending pedicel, the stipe 2.5-3 mm, the linear piano- compressed, nearly always strongly evenly retroarcuate body 3.5-6 x 0.75-0.9 cm, bicarinate by the sutures, the thinly papery stramineous or purple-tinged valves only slightly elevated over the seeds, remotely strigulose, finely venulose, the interseminal septa membranous narrow, the seed-locules 3-5 mm long, as wide as the cavity; seeds oblong-obovoid or pyriform, a little compressed parallel to the valves but plump, 3.6-4.7 x 2-3.5 mm, pinched at the hilum, the brown or brownish-olivaceous, dull or sublustrous testa smooth or almost so, the areole circular or elliptic dimple-like 0.5-0.8 x 0.4-0.5 mm.—Collections: 10.

    Arid rocky crests, banks and washes in desert and (n.-ward) in rainy-green loma formation, 100-1100 m, discontinuously dispersed along the Andean foothills and coastal hills from centr. Peru (Lima) to n. Chile (Antofagasta), in lat. 12°-25°S.—Fl. IV-V, VII-X.

    A species readily distinguished from all others in Pacific South America by the bifoliolate leaves and papery pods curved backward in a strong but variable arc. According to Bentham (1871, l.c.), occasional quadrifoliolate leaves occur, but as we have not encountered such in any modern collection of S. brongniartii, we believe they must be of a random or freakish nature and accordingly have omitted mention of them in the foregoing description.

    The synonymy, worked out by Johnston (1929), is firmly established and requires no comment. It seems probable that Bentham considered Cassia brongniartii to be an unpublished name, for he examined the material of it in Paris and perfectly understood its identity. The protologue consists of the plate alone, unaccompanied by descriptive matter other than captions published subsequently; but under Article 44 of the Code the conditions for validity are amply met.