Monographs Details: Cassia bifoliola Glaz. ex Harms
Authors:Howard S. Irwin, Rupert C. Barneby
Authority: Irwin, Howard S. & Barneby, Rupert C. 1978. Monographic studies in Cassia (Leguminosae, Caesalpinioideae). III. Sections Absus and Grimaldia. Mem. New York Bot. Gard. 30: 1-300.
Family:Caesalpiniaceae
Description:Distribution and Ecology - Campo limpo, in bare gravelly soil and creeping among grasses, near 1000-1200 m, local, known only from the headwaters of Rio Corumba (between Anapolis and Corumba de Goias) in s.-e. Goias and the adjoining s.-w. corner of Distrito Federal (Ponte Alta). — Fl. IV-VII(-X). "Brasilien: Goyaz, Ponte Alta, Campo (Glaziou n. 21006a; herbace rampant).''

Species Description - Probably weakly suffruiticose, but the root (xylopodium) or caudex unknown, the flexuously humifuse or perhaps (in competition) sarmentose, strongly ribbed and angular, often livid stems up to ± 3-6 dm, appearing glabrous throughout and the amply bifoliolate lvs truly so, but the base of stem, primary axis of inflorescence, stipules and bracts all microscopically puberulent and perhaps when fresh subviscid, the leathery foilage concolorous, coarsely veiny both sides, the loose racemes arising from 1-2 distal lf-axils, incurved to vertical. Stipules erect, firmly carnose, subulate subterete or ventrally flattened, 1-3 mm, persistent. Lvs apparently unilateral along the humistrate stem, all aspiring to vertical, 3-8.5 cm, very shortly petioled; pulvinus ovoid, strongly inflated, when dry coarsely wrinkled stramineous, 1.5-2 mm; petiole stout, 2-10 mm, 0.9-1.5 mm diam, abruptly dilated under the pulvinules, widely openly sulcate ventrally, prolonged into a firm stipuliform seta 2-3 mm; lfts 1 pair, ascending vertically from tip of petiole, turned half face to face on transversely dilated, when dry wrinkled pulvinule ±1.5 mm, in outline elliptic-oblanceolate to narrowly oblong-obovate, (2.8-)4-8 x 1.4-2.8 cm, at apex obtuse to deltate-acute, sharply mucronate by the excurrent midrib, at asymmetric base rounded to broadly cuneate on proximal and cuneate on distal side, the entire plane margin corneously thickened, the blades coriaceous, on both sides olivaceous dull or sublustrous, the midrib prominulous both sides but more so and cariniform (often purplish) beneath, the ±7-11 pairs of secondary veins bluntly subequally prominent both sides, forming a coarse irregular mesh of plane areoles much >1 mm diam, the first secondary nerve on the proximal side of each leaflets often longer than the rest, produced ± to middle of lft. Racemes simple or at base incipiently paniculate-branched, arising from 1-2 (more ?) distal lf-axils, loosely ± 10-24-fld, the puberulent axis becoming 5-1 5 cm; bracts subulate, appressed, 1.5-3 mm, persistent; pedicels ascending, 13-22 mm, glabrous or almost so, bracteolate 0.5-3 mm below calyx; bracteoles resembling bracts and scarcely smaller, persistent; buds ovoid-ellipsoid, obtuse, glabrous; sepals (probably reddish with pallid margins) elliptic, 9-12 x 2.6-3.7 mm; petals (of Absus, little known) yellow, the four homomorphous ones up to ± 11-13 x 6-7, the fifth firmer, oblique and coiled; ovary densely setulose; ovules ±5. Pod oblong-elliptic, straight or almost so, 3.3-4 x 0.75 cm, the valves bulbous-setulose. — Collections: 4.

Discussion:

A distinctive cassia, notable for the flexuously humifuse, perhaps sometimes incipiently sarmentose stems arising probably from a xylopodium, the bifoliolate leaves consisting of two plane leathery blades standing vertically erect from tip of a very short, widely grooved petiole and subequally veiny on both sides, and the almost glabrous inflorescence giving rise to bulbous-setulose or sometimes merely puberulent pods. The growth-habit of C. bifoliola suggests the perhaps marginally sympatric C. campicola, which differs greatly in its setose and dorsiventrally differentiated leaflets intricately alveolate-reticulate and pubescent beneath. The smooth stems with abbreviated, broadly and openly sulcate petiole and concolorous leaf-blades might suggest an affinity to C. planifolia and C. lavradioides, but these are quickly distinguished by their erect stems, differently shaped leaflets (in the first broadly ovate and in the latter at once cuneate at base and much smaller), and the marked viscidity characteristic of ser. Incurvatae. We suspect a closer kinship, however, to distantly allopatric species of ser. Ochnaceae, especially to C. ochnacea var. purpurascens, quite similar in texture and venation of the leaflets, in the form of the inflorescence, and the blunt glabrous flower-buds, but different in having two or more pairs, not a single pair, of leaflets.

This rare cassia was collected first in June, 1819 by Auguste de Saint Hilaire at a settlement on the upper Corumba river known as Sao Antonio dos Montes Claros (no. C 1/674, P).

Distribution:Distrito Federal Brazil South America| Goiás Brazil South America| Brazil South America|

Narratives:Cassia bifoliola