Cassia planaltoana Harms
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Authors
Howard S. Irwin, Rupert C. Barneby
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Authority
Irwin, Howard S. & Barneby, Rupert C. 1978. Monographic studies in Cassia (Leguminosae, Caesalpinioideae). III. Sections Absus and Grimaldia. Mem. New York Bot. Gard. 30: 1-300.
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Family
Caesalpiniaceae
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Scientific Name
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Type
Holotypus, †B = F Neg. 1732; clastotypus (fragm), F! neoholotypus, former isotypus, P! = NY Neg 6923; isotypi, G, K = IPA Neg. 1169 = NY Neg. 1553, LE, S!
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Description
Species Description - Small sturdy undershrubs with several to 50 or more smooth subterete, mostly simple or distally shortly branched stems arising annually, erect or obliquely erect from a xylopodium, 2.5-6.5 (-7.5) dm, appearing glabrous up to the yellow-setulose, viscous terminal inflorescence, but the stems beyond middle, lf-stalks, and Ift-margins thinly setulose (not villosulous) the foliage olivaceous concolorous, the inflorescence not or little exserted. Stipules erect, linear-attenuate or setiform, (2-)3-10 mm, persistent. Lvs stiffly ascending at narrow angles to vertical, (2.5-)3-9 cm, heteromorphic, the lowest simpler and longer-petioled than the distal ones, the latter sometimes subsessile; pulvinus scarcely dilated or discolored, 0.2-1.2(-1.5) mm; petiole 5-20(-24) mm, or of some upper leaves (1 -) 1.5-6 mm, at middle 0.5-0.8(-0.9) mm diam, openly grooved between the green margins; rachis (1-)2-6 (-7) cm; lfts of lower lvs 2-5, of median and upper lvs at least 5, commonly 6-10(-12) pairs, moderately spaced or crowded along rachis and then imbricated when pressed, usually a bit diminished upward, divaricate or widely ascending from rachis, resupinately tilted, proximal margin toward the meridian, on ±spirally wrinkled pallid or livid pulvinule 0.4-0.9 mm, in outline elliptic, oblong-elliptic, ovate-elliptic, less often obovate- or ovate-suborbicular, acute, obtuse and mucronulate, or obtuse to emarginate, (6-)8-24(-26) x (4-)5-14(-15) mm, at oblique base cordate on the (structurally) distal side, decurrent to rachis on proximal side, the plane margin setulose and then often shallowly crenulate or rarely smooth and entire, the blades firmly chartaceous, on both faces glabrous, olivaceous to brownish-olivaceous, dull or sublustrous, the midrib above immersed or slightly prominulous, the 3-6 pairs of secondary veins immersed above, prominulous beneath, the tertiary venulation immersed. Inflorescence a single terminal raceme or 2-4 either naked or leafy-bracteate ones forming a small panicle, the lateral racemes sometimes reduced to a single long-pedicelled fl, the individual raceme-axes ± 7-40-fld becoming 2-10 cm, the whole scarcely or not exserted from foliage, the 1-3 simultaneously expanded fls elevated ± to level of the pseudo-corymbose buds; bracts submembranous, pallid or castaneous, narrowly triangular to lanceolate or lance-attenuate, (1.2-)2-5(-8) mm, persistent; pedicels ascending, very slender, 1 -2.2(-2.5) or some solitary leafy-bracteate ones up to 2.5-3 cm, bracteolate 0.5-7(-9) mm below calyx; bracteoles resembling bracts, (0.5-)1.2-2.8 mm, persistent; buds plumply ovoid, obtusely apiculate or truly obtuse, glabrous or minutely puberulent in lower half, minutely setulose only in Mato Grosso; sepals subpetaloid, yellow, the outer ones often tinged with bright or brownish red, mostly obtuse or subobtuse, (6.5-)7-10(-11) x 2.6-5 mm, all widely expanded at anthesis; petals yellow, widely expanded, four plane, varying from flabellate-cuneate to broadly oblanceolate-cuneate, of unequal lengths, the largest 14-19 x 8-1.4.5 mm; ovary densely yellow-setulose; ovules (4)5-7(8). Pod linear-oblong or elliptic-oblanceolate, straight or slightly curved downward, 2.5-4.7 x 0.6-0.9 cm, the reddish-brown valves glutinous, either setulose or both villosulous and setulose, smooth or almost so; seeds unknown. — Collections: 18.
Distribution and Ecology - Campo and campo cerrado, in either rocky or sandy soils, 975-1225 m, locally common on headwaters of Rios Sao Bartolomeu and Descoberto in Distrito Federal, n. and s.-w. just into adjoining Goias, to San Gabriel de Goias and the valley of Rio Corumba; a form, not at present distinguishable except by the thinly setulose sepals, widely disjunct in Serra de Maracaju (mun. Camapua), s. Mato Grosso. — Fl. IX-III.
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Discussion
One of several functionally herbaceous, erect Absus cassias found on the central highlands of Goias, C. planaltoana habitally resembles C. adenophora and C. foederalis, but is probably more closely related to the diffuse or humifuse C. decumbens, which it resembles in the setulose, not pilosulous pubescence, and in the leaflets resupinate along their long axis so as to bring the proximal margin uppermost, edgewise to the sun. Where the ranges of C. decumbens and C. planaltoana overlap in the outskirts of the city of Brasilia the latter is partly (but not everywhere) represented by a form with the erect stem of the species but leaflets, even of most upper leaves, reduced in number to 2-5 pairs. Specimens of this form forcibly suggest passage into C. decumbens, but may be distinguished by the short, glabrous or minutely puberulent, not setose calyx. Experimei alone can determine whether these somewhat intermediate types are simple phenotypical variants of C. planaltoana or the result of introgression from its sympatric relatives.
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Distribution
Goiás Brazil South America| Distrito Federal Brazil South America|