Monographs Details: Cassia acosmifolia Mart.
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.
Description:Species Description - Slender often vinelike shrubs and weakly suffrutescent herbs (0.5-)1 -4 m, with 1 -few ascending or reclining, commonly sarmentose, awkwardly few-forked stems branching distally into a complex leafy thyrsiform panicle of racemes, the old stems or trunks brown or livid, smooth, furrowed, or striped lengthwise but not conspicuously exfoliating, commonly in all parts minutely villosulous and the branchlets, lf-stalks and inflorescences in addition hispid or hispidulous with yellow setules up to 0.2-1.5(-2) mm, the thin-textured bicolored lfts commonly pubescent on both faces but rarely glabrous above, the racemes either immersed in foliage or distally well exserted.
Stipules either erect or in age recurved to reflexed, firm or submembranous, subulate, 1-3.5 mm, persistent.
Lvs spreading and ascending, 3-11.5 cm, petiolate; pulvinus pallid or livid, subterete or ovoid, when dry ±wrinkled, (1 -)2.2-3 mm; petioles (0.9-)1.1 -4.2 cm, either a little shorter or a little longer than the first pair of lfts, at middle narrowly winged and openly shallow-sulcate, 0.3-0.8 mm diam; rachis (3-)4-18(-22) mm; lfts 2 pairs, displayed as other Absoideae on cylindrical or narrowly ovoid, mostly pallid pulvinule 0.8-1.8 mm, in outline ovate to broadly lance- or ovate-elliptic, obtuse or minutely emarginate and mucronulate or strongly mucronate, (0.9-)1.5- 6(-7.5) x (0.5-)0.7-2.8(-3) cm, at base on distal side mostly cuneate, on proximal, rarely both sides rounded to subcordate, the entire, ciliolate, sometimes minutely setulose margin revolute, the blades thinly chartaceous, above brownish-olivaceous, dull or faintly lustrous but hardly glutinous, finely pilosulous or less often glabrous, beneath pallid and always finely pilosulous, the slender, often pallid midrib and 5-10 (12, in larger lvs mostly at least 7) pairs of secondary with some few irregular tertiary venules prominulous both sides but more sharply so beneath, the ultimate mesh ill-defined, the areoles mostly > 1 mm diam.
Inflorescence thyrsoid-paniculate, the individual racemes subsessile, mostly terminal to leafy lateral branchlets, sometimes distally becoming simply axillary, the 1 -3 expanded fls displayed at or well below the unopened buds, the slender, often flexuous axis becoming 1-20 cm; bracts spreading-incurved, submembranous, triangular- or linear-subulate, 0.7-2.5 mm, persistent; pedicels very slender, 8-22 mm, bracteolate 1-7 mm below calyx, at anthesis ascending, in fruit variably spreading-incurved, divaricate, or deflexed; bracteoles resembling bracts but usually only 1/2 as large, persistent; buds ovoid or inversely pyriform, if apiculate obtusely so, either densely pilosulous or thinly setulose or both; sepals greenish to faintly red-tinged or livid-lineolate, ovate to narrowly lanceolate, obtuse, 8-10.5 x 1.8-3.4 mm; petals yellow, the four plane ones campanu- lately ascending, obovate-cuneate, slightly unequal, the longest 12-15.5 x 6.5-10 mm, thedimidi- ately ovate fifth one paler, about as long but coiled over androecium; ovary densely gray-villosu- lous, rarely also setulose; ovules mostly 6-7.
Pod variably orented, linear-oblong, 2.8-5.3 x 0.55-0.9 cm, the viscid reddish-brown valves minutely villosulous and rarely also setulose; ripe seeds not seen.
A weakly assurgent but often sarmentose and vinelike cassia of thickets and gallery-margins, over and through which its leafless ropelike trunk leans and scrambles, C. acosmifolia is habitally similar and closely related to C. barbata, but easily distinguished in practice by the open, irregular reticulation of the leaflets and by the dispersal of the flowers into a panicle of several or many relatively small racemes rather than their concentration into few and massive terminal ones. As defined in the description, the species is rather uniform in gross aspect, but includes a wealth of finely detailed variability of significance hard to interpret at the present time. It may perhaps conceal more than one discrete species, but these will emerge clearly only as more material from northeastern Brazil is studied. Three as yet somewhat shadowy entities, differing in degree of woodiness, in organization of the inflorescence, in shape of sepals and as result in outline of the flower-buds, and in minor features of pubescence and pod, are provisionally described herein as geographical varieties.
Key to the varieties of C. acosmifolia
Floriferous branches of current season's growth 0.3-3 dm, the compound inflorescence organized around a woody, smooth or remotely and minutely setulose (setules 0.2-0.b(-0.b) mm), not villosulous parent axis; fls crowded along a raceme-axis 1-8 cm the intervals between floral bracts 1-4 mm; fl-buds inversely pyriform, subcorymbosely displayed near level of the expanded fls; sepals narrowly lanceolate, 1.8-2.8 mm wide, Maranhao, Piaui,Bahia.
148a. var. acosmifolia
Floriferous branches of current season at least 6 dm, the compound inflorescence organized around a green herbaceous parent axis hispid with setae up to 0.6-1 -5(-2) mm, fls, except in rare var. euryloba of Minas Gerais, distant along a raceme-axis (2-)4-20 cm, the intervals between floral bracts 5-20 mm; fl-buds subglobose or plumply ovoid, racemosely elevated at least shortly above the expanded fls; sepajs more broadly lanceolate to ovate-elliptic, 2.8-3.4 mm wide; e-centr. Mato Grosso, Goias, Minas Gerais.
2. Fls loosely racemose, as described above; fl-buds thinly setulose but seldom and only remotely villosulous; pod slender, 2.8-3.6 x 0.55-0.65 mm, the valves villosulous, not setulose; e.-centr. Mato Grosso to e.-centr. Goias.
148b. var. oropedii
2. Fls crowded almost as var. acosmifolia, but stems and pubescence of var. oropedii, fl-buds densely pilosulous; pod longer and broader, 4.5-5.3 x 0.8-0.9 cm, the valves both villosulous and finely setose; upper Rio Jequetinonha basin on e. slope of Sa. do Espinhaço, n.-e. Minas Gerais.
148c. var. euryloba