Cassia gracilis Kunth

  • Authority

    Irwin, Howard S. 1964. Monographic Studies in Cassia (Leguminosae-Caesalpinioideae). I. Section Xerocalyx. Mem. New York Bot. Gard. 12 (1): 1-114.

  • Family

    Caesalpiniaceae

  • Scientific Name

    Cassia gracilis Kunth

  • Description

    Species Description - Erect slender shrub or subshrub, simple at base, much branched above, to 0.6 m tall. Stems smooth, glabrous, dark violet-brown. Stipules usually caducous, seldom persisting below third node, minute, lanceolate or broadly lanceolate, acuminate, 2.0-2.8 mm long, 0.7-1.4 mm broad, sessile or slightly elevated. Leaflets bijugate, the inferior pair usually longer, sessile by a minute arcuate pulvinule, obovate-oblong, obtuse or rounded, oblique or falcate, glabrous, membranaceous, 0.6-1.2 cm long, 0.2-0.4 cm broad, venation indistinct. Flowers solitary or in pairs, produced more or less continuously; pedicels filiform, usually straight, glabrous or rarely sparsely puberulent in a line, 1.2-2.0 cm long in flower, up to 2.7 cm long in fruit; bracts 1 or 2, caducous, triangular, 0.5-0.7 mm long, 0.3-0.5 mm broad; bracteoles remote, appressed, persistent, linear or linear-lanceolate, 1.0-1.4 mm long, 0.3-0.5 mm broad; sepals lanceolate, glabrous, 0.5-0.7 cm long, 1.5-2.5 mm broad; petals 0.5-0.7 cm long, 0.4-0.6 cm broad; ovary pubescent with appressed giayish hairs. Pod oblong to obovate, 1.4-1.7 cm long (exclusive of the often persistent style), 0.4-0.6 cm broad, valves slightly cristate over seeds, glabrous or very sparingly appressed-pubescent. Seeds 4-6, flattened, 3.5-4.5 mm long, 1.7-2.2 mm broad. Chromosome number: not determined.

  • Discussion

    Chamaecrista gracilis (Kunth) Pittier, 3rd Conf. Interam. Agric. Caracas: 373. 1945.

    Although DeCandolle (1825) and Vogel (1837) followed Kunth's circumscription of C. gracilis, Bentham (in Martius, 1870) broadened the concept of this species to include the superficially similar Pohl 906 (F, K) : "Serra da Chrystaes", from Goias. In addition, Martius described var. erythrocalyx, based on one of his own collections from Minas Gerais, and characterized by its long-persistent stipules and a reddish calyx.

    In examining Pohl's specimen, and others which have since been collected, it has become clear that the Brazilian material differs from the Orinocan in numerous respects, among them: stipules more persistent, cordate-ovate; petiole ca. 0.5 mm thick (0.2-0.3 mm thick in Orinoco material); gland distinctly stipitate; leaflets lanceolate or linear-lanceolate, the superior pair longer, venation prominent on undersurface; pedicels 2.0 cm long or longer; petals 1.5 cm long or longer; ovary and pod glabrous. In fact, Pohl's material is singularly diminutive in comparison with other Goias collections of similar character (e.g. Glaziou 20991 and Irwiji 2606), by which it is clearly related to C. langsdorffii var. parvifoliola. Furthermore, Bentham's circumscription involved a distributional disjunction of some 1800 miles which has not yet been reduced by any subsequent collections. Although Trans-Amazonian disjunctions of this magnitude are not unknown, e.g. in the euphorbiaceous Tetrorchidium rubrivenium Poepp. & Endl. (Smith & Downs, 1959), the morphological dissimilarities exhibited in the 2 regions argue more in favor of approximate morphological convergence than common phyletic origin. Accordingly, the Brazilian material which Bentham included in C. gracilis is segregated as C. langsdorffii var. tenuis.

    Martius's C. gracilis var. erythrocalyx, based on one of his own collections from the mountains of Minas Gerais probably in the vicinity of Diamantina, exhibits a character frequently seen in other taxa of section Xerocalyx: a reddish or purplish tinge to the calyx, and to the young stipules and leaves as well, probably reflecting mineral deficiencies in the soil. This is undoubtedly a phenotypic expression, and the forms concerned should not be accorded nomenclatural recognition; therefore var. erythrocalyx has been regarded as a synonym of C. gracilis (sensu Benth.).

    Photograph of figure (t.36) examined (NY) : Venezuela, "Orinoco River near San Borja." The illustration depicts all salient characters except mature fruit. The type specimen, presumably a collection of Humboldt, could not be found.

  • Distribution

    Distribution: Colombia and Venezuela along the upper Orinoco River, between the tributaries Rio Aripe and Rio Ventuari. Occurring in savannas on sandy soils and crystalline outcrops.

    Venezuela South America| Colombia South America|