Monographs Details: Chamaecrista desvauxii var. piptostegia H.S.Irwin & Barneby
Authors:Howard S. Irwin, Rupert C. Barneby
Authority: Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 2: 455-918.
Family:Caesalpiniaceae
Description:Latin Diagnosis - Chamaecrista desvauxii (Colladon) Killip var. piptostegia Irwin & Barneby, var. nov., var. mollissimae (Bentham) Irwin & Barneby quam maxime affinis sed stipulis cito (diu ante folium lapsum) deciduis, caulibus annotinis ideo nudis abstans.

Species Description - When adult erect, bushy-branched distally, up to 7-12 dm, the purplish-castaneous stems pilosulous when young, the olivaceous lfts either glabrous or glabrous ciliolate; stipules submembranous, lance-oblong, obtuse or abruptly acute, up to 6.5-14 x 2.5-6.5 mm, all deciduous before the associated lf; lf-stalk 5-11 (-12) mm, the petiole 3-7 mm, the rachis 1-2 mm; petiolar gland 0.5-1.1 mm diam, sessile or elevated on a low mounded stipe as wide or slightly wider than head; lfts oblanceolate or narrowly obovate-elliptic obtuse or subacute, the larger of larger lvs 20-42 x 5—12(—14) mm, the distal pair often much longer than the proximal one and often a trifle arched backward; pedicel, fl and pod of var. mollissima.

Distribution and Ecology - Campo or savanna, on white sand, quartzite, or sandstone, ±250-500 m, interruptedly dispersed around the n., w. and s. periphery of the Amazon Basin: sources of Rio Vaupés (ríos Kubiyu and Kuduyari) in Vaupés, Colombia; middle Orinoco valley in n.-w. Amazonas, Venezuela; Guayana Highland in Bolívar, Venezuela (Gran Sabana near Uriman); Sa. Tumucumaque and vicinity, along the frontier in Surinam, Brazil (Pará, Amapá) and probably French Guiana; and on middle and upper Rios Xingú and Araguaia in s.-e. Pará and n.-e. Mato Grosso (Parque Nacional do Xingú; Sa. do Roncador).—Fl. apparently the year round.

Discussion:

Readily distinguished from glabrous forms of var. mollissima, which it otherwise closely resembles, by early loss of the membranous stipules, the year-old stems in consequence naked and not clothed in gray marcescent tatters. Like other discontinuously dispersed forms of Ch. desvauxii, the var. piptostegia consists of major geographic populations that are minutely different and technically separable, possibly indeed independent but parallel modifications of the protean ancestral stock of tetraphyllous xerocalyx. The Colombian plants (holotypus; Garcia Barriga et al. 16043; Schultes & Cabrera 18321) have glabrous leaflets, sessile glands, and relatively long petioles; those from northeastern Brazil and adjoining countries (Steyermark 75288; Oldenburger ON-166; Fittkau & Coêlho in INPA 12835; Cavalcante 2512; Pires & Cavalcante 52023) have ciliolate leaflets, glands raised on a mounded pediment, and proportionately very long distal leaflets bent backward in the style of the narrow-leaved form of Ch. diphylla that has been known as C. cultrifolia; while the Xingú-Araguaia populations (D. Coelho in INPA 15877; Fróes 29821; Argent et al. 6640; Santos et al. in Ratter 1496) combine ciliolate but ampler leaflets with sessile glands.

Distribution:Vaupés Colombia South America| Colombia South America| Amazonas Colombia South America| Venezuela South America| Bolívar Venezuela South America| Brazil South America| Pará Brazil South America| Amapá Brazil South America| French Guiana South America| Pará Brazil South America| Mato Grosso Brazil South America|