Chamaecrista desvauxii (Collad.) Killip var. desvauxii
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Authors
Howard S. Irwin, Rupert C. Barneby
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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.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Cassia desvauxii Colladon, Hist. Casses 131. 1816, sens. str., based on C. tetraphylla Des- vaux, Jour. Bot. 3: 72. 1814 & Ann. Sci. Nat. I, 9: 428. 1826 (sub C. desvauxii), descr. ampliat.—"Habitat in America calidiore. Holotypus, annotated by Amshoff in
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Synonyms
Cassia desvauxii Collad., Chamaecrista desvauxii var. mollissima (Benth.) H.S.Irwin & Barneby, Chamaecrista tetraphylla (Desv.) Britton & Rose, Cassia adscendens Colla ex Mart., Cassia uniflora var. glaucescens Vogel, Cassia langsdorffii var. longipedicellata H.S.Irwin, Cassia tetraphylla var. littoralis H.S.Irwin
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Description
Species Description - Prostrate or weakly ascending, the branches often adventitiously rooting where in contact with ground, the pedicels ascending toward the meridian; foliage (so far as known) glabrous, the stems, lf-stalks and pedicels varying from glabrous to pilosulous, the lf-stalks sometimes setulose, the lfts bright green or blue-green, not known to be glaucous; larger stipules (near middle of stems) ovate to broadly lance- or oblong-ovate acute up to (6—)7— 16(— 18) x (3—)4—6(— 10) mm, half as long to a little longer than internodes, those of terminal branchlets late in season smaller; lf-stalk of larger lvs 4-12 mm, the rachis 2-4 mm; gland 0.3-1.6 mm diam, either sessile and scutellate to urceolate or stoutly short-stipitate, then in profile peg- or funnel-shaped and up to 0.7(-l) mm tall; larger lfts broadly oblanceolate to broadly obovate obtuse up to 11-25 x 5-10 mm; pedicels (2-)2.5-5.5 cm; longest sepal 9-18 mm; longest petal of early fls 11—15(—20) mm, of some late fls only 7-10 mm; pod 30-55 x (5-)5.5-7.5(-8) mm, glabrous or pilosulous; ovules 12-22.
Distribution and Ecology - Interruptedly widespread over s.-e. Brazil but of bicentric range: on dunes and in coastal restingas along the Atlantic coast from n. Bahia to Paraná; and on sandy or gravelly soils of campo and campo cerrado at 300-1100 (in centr. Minas Gerais to 1300) m, scattered over the Planalto from centr. Bahia (Sa. do Tombador) to centr. Minas Gerais, s.-w. across centr. and s. Goiás to n.-e. and s.- centr. Mato Grosso (Sas. do Roncador and São Gerónimo).-Fl. year round along the coast, mostly X-III inland. ).
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Discussion
Our concept of var. desvauxii is coextensive with the combination Cassia tetraphylla var. littoralis + C. langsdorfii var. longipedicellata of the last revision (Irwin, 1964) and consists of those races of Ch. desvauxii in which a prostrate, often adventitiously rooting habit coincides with broad leaflets, sessile or only short-stipitate glands, and flowers of moderate size. It may very likely embrace at least two, possibly more numerous, phyletically independent mutations, but the coastal and interior phases are certainly no longer morphologically separable, the distinction between puberulent pedicels (C. tetraphylla) and glabrous ones (C. langsdorfii) being no longer tenable. On the Atlantic coast and in interior Bahia var. desvauxii is sympatric with Ch. ramosa, different in the small leaflets and emphatically stipitate glands, and on the Planalto in Goiás and Mato Grosso with vars. mollissima, langsdorfii, and glauca, collectively different in their more or less upright, bushy or wandlike habit of growth. Plants of the form prevalent in the interior are notable in the field for the blue-green tone of the foliage and the attitude of the pedicels, ascending toward the meridian from the prostrate stems.
Reinterpretation of original Cassia desvauxii as equivalent of the maritime southern plant latterly known as C. tetraphylla var. littoralis and not the Amazonian one to which the name has been applied is based on comparison of the holotypus, not available to Irwin in 1964, with our copious material from restingas of coastal Rio de Janeiro and Guanabara. These maritime populations are subject to seasonal dimorphism, an amply leafy aspect prevalent in wet fall months giving way to a more or less microphyllous one in the dry season. Desvaux’s plant corresponds in minute detail with the latter phase, and is matched especially closely with the distal branchlets of Fuad Atala 285 (NY) which conveniently retains toward the base of the stems some of the ample early foliage. There is no exact record of origin for Desvaux’s specimen, but it could well have been among the plants collected at Rio de Janeiro in 1767 by Commerson on Bougainville’s expedition around the world.
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Objects
Vouchers for limital records of var. desvauxii are: Bahia: Sa. do Tombador, Irwin et al. 30522, 30602 (NY). Mato Grosso: Sa. do Roncador, Irwin et al. 16403, 16625 (NY); w. of Coxim, Nienstedt 48 (NY). Paraná: Caioba to Matinhos, Lindeman & de Haas 2622, 5065 (NY
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Distribution
Brazil South America| Bahia Brazil South America| Paraná Brazil South America| Minas Gerais Brazil South America| Bahia Brazil South America| Mato Grosso Brazil South America| Goiás Brazil South America|