Monographs Details: Chamaecrista desvauxii var. langsdorfii (Kunth ex Vogel) 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
Synonyms:Cassia langsdorffii Kunth ex Vogel, Chamaecrista langsdorffii (Kunth ex Vogel) Britton ex Pittier, Cassia borbonioides Vogel, Chamaecrista lehmannii Britton & Rose, Cassia chartacea H.S.Irwin var. chartacea
Description:Species Description - Erect, at first simple and few-branched distally or (rarely) few-stemmed from base, the lateral stems stiffly ascending, when adult frutescent and stiffly branched upward, the branches either ascending or plagiotropic, the whole at anthesis (2-)3-16(-20) dm, the lvs mostly abruptly divaricate, the olivaceous or pallidly subglaucescent foliage commonly glabrous, the stipules and lfts less often ciliolate, the stems varying from glabrous to strigulose or pilosulous, the petioles often dorsally setulose; stipules ovate- or lance-acuminate or abruptly acute, almost always as long or longer than internodes, persistent, the larger up to 12-24 x 2.5-8(-9) mm; lf-stalks of longer lvs 4-10(-ll) mm, the petiole 3-8.5, the rachis ±1-2 mm; petiolar gland scutellate or shallowly concave (0.3-)0.4-1.6 mm diam, usually sessile and when both small and sessile sometimes depressed into the sulcus and inconspicuous, less often raised on a short stout stipe and becoming in profile drum- or squatly tack-shaped, but shorter (exceptionally a trifle longer) than diam of head; lfts narrowly elliptic, oblong-elliptic, linear-oblanceolate or sublinear, acute or obtuse mucronulate, the distal pair usually a trifle longer than the proximal, the larger lfts up to (12-) 15-26 x 2-6(-6.5) mm, (3—)3.5—8(—10) times longer than wide, the blades varying from submembranous to stiffly chartaceous, the stiffer ones bordered by a raised pallid marginal nerve; pedicels 8-30(-38) mm, mostly as long or shorter, rarely a little longer than lf, either glabrous, or puberulent on one or both faces; long sepal (11 —) 12— 19(—20) mm; long petal (10—) 11—18 mm; pod (26-)30-52 x (5.5-)6-7.5(-9) mm, thinly strigulose or the faces sometimes glabrous; ovules (9—) 11—18(—22).

Distribution and Ecology - Cerrado and campo, sometimes about outcrops and often locally abundant, along with microphyllous Melastomataceae, on seeps or moist rocky stream banks, mostly 500-1100, on Chapada dos Veadeiros up to 1400 m, widespread and locally common over the centr. highlands of the Brazilian Planalto from e. centr. to s.-w. Goiás, w. across Rio S. Francisco to the w. slope of n. Sa. do Espinhaço (Montes Claros) in Minas Gerais, thence s. along the Serra to Sa. do Itabirito and along Sa. Geral into the Triângulo, with outlying stations on the headwaters of Rios Paraiba and Paranapanema respectively in far e. São Paulo and n.-e. Paraná, on Sa. de Amambay in e.-centr. Paraguay, in centr. Mato Grosso (near Cuiabá), and distantly disjunct at ± 1200 m on upper Río Magdalena in Huila, Colombia (near 3°N).—Fl. mostly X-IV, in moist places nearly throughout the year.

Discussion:

While the range of dispersal (except for the Colombian extension, due to taxonomic decision) of the taxon langsdorfii has not been extended over that mapped by Irwin (1964, l.c.), the amount of material available for comparative study has tripled, compelling us to modify quite radically the former concept. Before going further, we have to correct the misinterpretation of Cassia langsdorfii sens. str. of the last revision. Vogel described C. langsdorfii (the spelling was altered by Bentham to "langsdorffii") and C. borbonioides as close kindred different principally in pubescence, the former having ciliolate leaflets with variably pubescent pedicels whereas the latter was glabrous below the ovary. Obviously a circumscription and key that attributed to C. langsdorfii a prime differential character of glabrous pedicels was an unhappy error. We are now satisfied, however, that pubescence of the pedicels has neither taxonomic nor biological significance in sect. Xerocalyx, so that in effect we are able, following modification of the definition, to maintain the epithet langsdorfii for the same material, with which we now associate the pubescent analogue segregated as C. chartacea.

The central and prevailing expression of the newly defined, more heterogeneous var. langsdorfii described above is an erect plant, at first single-stemmed with either ascending or plagiotropic branches, lance-oblong stipules normally concealing the intemodes, and petioles, of the length found in var. mollissima, abruptly divaricate from the stem; but different from var. mollissima in the narrower, mostly linear-elliptic or narrowly oblong-elliptic, acute or less often obtuse leaflets consistently glabrous facially but either ciliolate or not so, coinciding wth flowers of moderate size. While most mature plants of this nature attain a stature of less than one meter, some old ones, especially where growing in thickets at the edge of gallery woodland or along streams, become shrubby and up to two meters tall; but whether these are genetically distinct or merely aged individuals of the common wandlike type we do not know. The gland of var. langsdorfii is now seen to vary enormously in size, but is only rarely elevated on a stout stipe and even then not taller than the diameter of the head. When very small it may be concealed between the ventral wings of the petiole but usually projects beyond them. The leaflets vary in texture from firm, with pallid thickened (always glabrous) marginal nerve, to chartaceous with sharp (either glabrous or ciliolate) margins, but we can no longer expect correlation between texture of leaf-blades and size of glands. As a consequence C. chartacea var. chartacea, which seemed in the light of a small sample specifically distinct in its syndrome of thin-textured leaflets, small glands, and pubescent pedicels, has faded to the status of a poorly differentiated minor variant. The type-collection of C. chartacea, of which the precise origin is unknown, is somewhat unusual in having, along with the supposed differential characters already mentioned, obtuse leaflets and relatively small stipules that do not overlap along the stems as an imbricated thatch. The few precisely similar modern collections come from the northwest corner of Distrito Federal near Sobradinho, Planaltina and Formosa, and we suspect that Martius may have collected the typus somewhere on the headwaters of Rio Paranã close beyond the present confines of the District.

The var. langsdorfii occupies a position crucially central at once to the whole curve of phenetic variation in tetraphyllous xerocalyx and to its focus of maximum diversity on the Brazilian Planalto. In southern Goiás it is in places narrowly sympatric with Ch. desvauxii var. glauca, var. mollissima, var. brevipes and var. modesta and with Ch. ramosa var. parvifoliola, var. lucida and var. erythrocalyx; and we have specimens ambiguously intermediate to all of them except var. glauca, with which it is connected however by way of var. mollissima. Our division of the tetraphyllous complex into two specific series primarily on the basis of petiole length casts var. langsdorfii (with C. chartacea var. chartacea) on the side of Ch. desvauxii and the very closely related and intergradient var. parvifoliola and var. erythrocalyx (with C. chartacea var. tenuicaulis) on that of Ch. ramosa. The artificiality of this surgical division is obvious, but we can find no more natural line of separation.

The typus of Ch. lehmanii, interpreted by Irwin (1964) as Ch. brevipes with paradoxically long pedicels, cannot be distinguished from some Brazilian var. langsdorfii and would be noteworthy in southern Goiás only for the relatively short stipules, a feature already encountered, as noted above, in the type-collection of C. chartacea. A second collection (Fosberg 19812) from Huila shows the characteristic wand habit of var. langsdorfii, not manifest in the typus.

Distribution:Goiás Brazil South America| Minas Gerais Brazil South America| São Paulo Brazil South America| Paraná Brazil South America| Paraguay South America| Mato Grosso Brazil South America| Huila Colombia South America| Colombia South America|

Multimedia: