Chamaecrista tragacanthoides (Benth.) H.S.Irwin & Barneby
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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
Typus infra sub var. tragacanthoide indicatur.
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Synonyms
Cassia tragacanthoides Mart. ex Benth.
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Description
Species Description - Subshrubs with many procumbent and ascending, at length freely branching stems, at anthesis 1.5-3.5 dm, arising after fire directly from a xylopodium but if undisturbed from elongating prostrate tortuous trunks and at length forming matted thickets up to 1 m diam, the densely leafy annotinous branchlets, lf-stalks and at least margins of lfts strigulose or puberulent with appressed, incumbent or incurved hairs up to 0.2-0.4 mm sometimes mixed with spreading setules up to 0.5-0.8 mm, the whole vesture extremely variable in density, sometimes extending as a dense silky appressed indument over both faces of the lfts, sometimes sparse and lfts glabrous on both faces, then concolorous dull pallid-papillate. Stipules stiffly erect, linear-lanceolate or triangular-subulate, (1.5—)3—7 x 0.4-1 mm, faintly 3-nerved, persistent. Lvs arcuately spreading 1-2.7 cm, ovate in expanded outline; petiole with poorly differentiated pulvinus 1.5-4 mm, at middle 0.4-0.6 mm diam, narrowly margined, the groove opened by the gland, closed distally; gland 1, situated near or above middle of petiole proper, sessile or subsessile, in outline round or elliptic 0.3—1 mm diam, when sessile urceolate-patelliform, when stoutly short-stipitate becoming drum-shaped, in profile much shorter than or up to 0.2 mm longer than diameter of the head; rachis 3-ll(-18) mm; lfts 3-7(-8, commonly 3-5) pairs, slightly decrescent upward, in outline subsymmetrically or retrofalcately linear-oblong, narrowly oblong-oblanceolate, or (especially the distal pair) obliquely obovate, obtuse and stoutly mucronate or abruptly apiculate, the larger of median lvs up to (5—)6—16 x 1.5—4 mm, at base cordate on proximal and cuneately rounded on distal side, from base 2-4-nerved by the straight or outwardly curved, centric or moderately displaced midrib with, on its proximal side, 1-3 weaker primaries, the inner (or only) one of these incurved-ascending beyond middle of blade, the outer ones much shorter, the midrib from near middle penniveined with 2-3(-4) pairs of secondary venules, tertiary venulation faint or immersed, primary venation usually prominent beneath, immersed or nearly so above, sometimes concealed by vesture. Peduncles exactly axillary subobsolete l(-2)-fld; pedicels 9-30 mm, bracteolate 3-6 mm below calyx; bracteoles ovate or lanceolate 1.2-4 mm; buds plumply ovoid-acuminate puberulent; sepals ovate- or lance-acuminate, often reddish, up to 7.5-10 mm; petals yellow, 4 obovate to broadly oblanceolate up to 11-15 mm, the falcately dimidiate one slightly longer; androecium 10-merous, the long anthers 4.8-6 mm; ovary white-strigulose; style linear, gently incurved, (4.5-)5-7.5 mm; ovules 6—8(—11). Pod ascending ±25-40(-45) x 4.5-5.5(-6) mm, the reddish-brown valves puberulent or finely pilosulous; seeds (scarcely known) ±3 mm, the testa dark brown sublustrous, finely pitted.
Variety Key - Key to the Varieties of Ch. tragacanthoides 1. Foliage densely silky-velutinous throughout with appressed sublustrous hairs, the branchlets similarly pubescent and often addition shortly setulose. 14a. var. tragacanthoides (p. 687). 1. Foliage green, the leaflets glabrous above, glabrous or almost so beneath, minutely ciliolate, the branchlets puberulent, not setulose. 14b. var. rasa (p.688).
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Discussion
A species well characterized by the low bushy habit of growth, densely leafy branchlets, and relatively few pairs of thick-textured leaflets. We can find in the now fairly copious material no difference other than the dense silky vesture to separate Cassia tragacanthoides sens. str. from glabrescent C. pachyphylla, which are, moreover, sympatric (if not actually directly associated in any known station) around Diamantina, in the same environment of the campos rasos near the Serra crest. The difference in pubescence is, in this particular case, sharply marked, the leaflets being either densely pubescent on both faces or green and minutely ciliolate, permitting the retention of C. pachyphylla in varietal rank. Key to the Varieties of Ch. tragacanthoides 1. Foliage densely silky-velutinous throughout with appressed sublustrous hairs, the branchlets similarly pubescent and often addition shortly setulose. 14a. var. tragacanthoides (p. 687). 1. Foliage green, the leaflets glabrous above, glabrous or almost so beneath, minutely ciliolate, the branchlets puberulent, not setulose. 14b. var. rasa (p.688).