Cassia cultrifolia Kunth
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Authors
Howard S. Irwin
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Authority
Irwin, Howard S. 1964. Monographic Studies in Cassia (Leguminosae-Caesalpinioideae). I. Section Xerocalyx. Mem. New York Bot. Gard. 12 (1): 1-114.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Photographs of holotype (F, GH, NY, TEX) in Botanisches Museum, Berlin, examined: Venezuela, "Herb. Willdenow. Cumuna." Humboldt s.n. w/o date (collected in Venezuela, 1799-1800).
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Synonyms
Chamaecrista cultrifolia (Kunth) Britton & Killip ex Britton & Rose
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Description
Species Description - Annual or short-lived perennial herb11 with erect or ascending, simple or few-branched glabrous stems, usually less than 1 m tall. Stipules often obscuring the upper stem, lanceolate-cordate, acuminate, 1.0-2.5 cm long, 0.4-0.8 cm broad, marginally ciliolate on apical one-third and on basal auricles. Petiole 3.0-7.5 mm long, prolonged beyond nodule as an aristate appendage, the abaxial groove glabrous to pubescent, the abaxial surface strigose or hirsute with distally-directed hairs 0.5-1.5 mm long. Gland scutellate or urceolate, 0.5-1.0 mm broad, sessile or rising from the groove on a short thick stipe. Leaflets unijugate, each joined to petiole by an oblique, linear, black pulvinule, linear-oblong or oblong, oblique or falcate, glabrous, subcoriaceous, 1.5-3.5 cm long, 0.4-1.2 cm broad, usually rather pale gray- or yellow-green; margins hyaline, ciliolate on the apical one-third. Flowers usually solitary, produced in continuous succession except in periods of drought; pedicels commonly arching upward, pilose, 1.8-3.4 cm long and ca. 0.5 mm thick in flower, up to 4.2 cm long and 1.0 mm thick in fruit; bracts 1 or 2, apparently caducous, ovate or narrowly ovate, 1.5-2.5 mm long, ca. 1.0 mm broad; bracteoles subopposite, appressed, linear or linear-lanceolate, 1.5-2.5 mm long, 1.0-1.5 mm broad; sepals linear-lanceolate or lanceolate, glabrous, 1.0-1.5 an long, 2.0-3.0 mm broad; petals 1.0-1.7 cm long, 0.6-1.2 cm broad; ovary pilose with appressed grayish hairs. Pod narrowly oblong, 3.5-5.0 cm long, 0.4-0.7 cm broad, the valves shallowly sulcate between the seeds, appressed-puberulent to pilose. Seeds 15-20, slightly compressed, 3.5-5.0 mm long, 1.5-2.0 mm broad. Chromosome number: n = 7.
Distribution and Ecology - Distribution: Venezuela and eastern Colombia, eastward through the Guianas to Amapá, Brazil, and southward through Rio Branco, Amazonas, and Pará to Mato Grosso and Goiás. Occurring in savannas and low open woods (i.e. "cerrado" in Brazil; "muri" in British Guiana) ; chiefly on sandy soils, at elevations usually less than 3000 feet, except in the region of the Pakaraima Mountains (British Guiana, Venezuela, Brazil) where occasional plants have been taken at ca. 4000 feet.
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Discussion
Cassia cultrifolia is one of the more stable taxa in the section Xerocalyx, showing relatively slight variability over the whole of its extensive range. The most marked variation is with regard to leaflet and stipule size and pedicel length, but these characters vary independently and present no meaningful regional patterns. Depauperate plants are often found on especially poor soils.
Unfortunately this species is not only rather inconspicuous, especially when not in flower, but also seems, in the present author’s experience, nowhere common. It is not surprising, then, that herbarium material is rather scant, especially from the south drainage of the Amazon and the northeastern portion of Brazil south of Pará.
C. cultrifolia seems most closely related to C. diphylla; certain forms of the latter have narrow leaflets which superficially resemble those of C. cultrifolia. However, in the few localities where both species were observed in relative proximity, no evidence of hybridization was seen.
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Distribution
Brazil South America| Amapá Brazil South America| Amazonas Brazil South America| Maranhão Brazil South America| Mato Grosso Brazil South America| Pará Brazil South America| Colombia South America| French Guiana South America| Suriname South America| Venezuela South America|