Cassia hedysaroides

  • Title

    Cassia hedysaroides

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia hedysaroides Vogel

  • Description

    107.  Cassia hedysaroides Vogel, Syn. Gen. Cass. 52 & in Linnaea 11: 689, descr. ampliat. 1837. - "In Brasilia: Sellow leg. in Serra do S. Antonio." — Holotypus †B = Field Neg. 1691; clastotypus (fragm), F! neoholotypus, former isotypus, K (hb. Hook.) = IPA Neg. 1055 - NY Neg. 1500! isotypi, G, K, LE, P = NY Neg. 6937! — Bentham, 1870, p. 145; 1871, p. 564.

    Cassia vernicifolia Harms ex Glaziou in Mem. Soc. Bot. Fr. 1 (3): 167. 1906 (pro parte), nom. nud. — "Birybiry, pres de Diamantina, MINAS, nos. 19070, 19071." — Spm. authent.: Glaziou 19071, C, K = NY Neg. 1556, P!

    Shrubs and treelets, glabrous and glutinous almost throughout (the branchlets exceptionally minutely puberulent), variable in habit, in exposed rocky sites a broad-headed, stiffly many stemmed bush from a stout woody base, up to (0.5-)1-2.5 m tall, in cerrado or regenerating woodland sometimes arborescent, up to 5 m with trunk up to 6 cm diam, the dark brown or blackish trunks, stiff wiry branchlets, lfts and all axes of inflorescence glandular-verruculose and lustrously resinous, the foliage bicolored, the leaflets dull olivaceous above, lustrous and resin-dotted beneath, the simply racemose inflorescences terminal to all the branchlets (the lowest sometimes becoming leaf-opposed), variable in length and number of flowers, little- or long-exserted from foliage.

    Stipules appressed to stem, deltate-triangular or subulate, 0.4-0.9 mm, persistent but often almost concealed by a coat of resinous exudate.

    Lvs ascending or spreading (2.5)3.5-12(14) cm, petioled; pulvinus moderately inflated, glutinously verruculose, 2-4 mm; petioles (0.6-) 1-2.5(-3.2) cm, (0.5-)0.6-0.9(-1.2) mm diam, narrowly sulcate ventrally; rachis (0.4-)1 -7(-9) cm; lfts commonly (2-)3-5, in some populations mostly 4-7(-8) or only 1-2(-3) pairs, tilted a little forward, face upward, on glandular-verruculose discolored petiolule 1-3 mm, of uniform size or slightly either accrescent or decrescent upward, in outline symmetrically oblong, oblong-obovate, or elliptic, obtuse or emarginate, mucronulate by the excurrent midrib, (0.8-) 1 -4.5(-5) x (0.4-)0.6-1.6(-1.8) cm, at base symmetrically rounded to subcordate both sides, the entire margin plane, the blades varying from stiffly or rigidly chartaceous to submembranous, bicolored, above olivaceous, dull, minutely papillate but not viscous, beneath darker olivaceous to brownish, lustrously glutinous and resin-dotted, the midrib above impressed or immersed, riblike beneath, the (4-)5-9(-14) pairs of major secondary veins faintly raised above, sharply so but subfiliform beneath, the tertiary venation imperceptible.

    Inflorescence terminal to branchlets, loosely or subcompactly racemose, 5-many-fld, the slender, straight or flexuous axis including short peduncle (1 -)2-15(-25) cm, the 1-3 fls simultaneously expanded at least in longer racemes standing below racemose buds; bracts subulate, 0.7-1.6 mm, deciduous; pedicels slender ascending (6-)8-20(-24) mm, bracteolate (1 -)2-5(-9) mm below calyx; bracteoles 0.4-0.9 mm, persistent; buds slenderly or plumply ovoid-acuminate, glandular-verruculose; sepals thin-textured, red-orange to yellow, elliptic or oblanceolate, acute, 8.5-11.5 x 2-4.5 mm, the broader inner ones membranous-margined, the tips of the outer ones often squarrose; petals yellow, four ascending at ±45°, of unequal lengths, oblanceolate to obovate-cuneate or -flabellate, the largest up to 9.5-13 x 4.5-7 mm, the fifth firmer, obliquely oblanceolate, coiled; ovary verruculose, glutinous; ovules 3-6.

    Pod broadly oblong, straight or slightly decurved, (1.7-)2-3.6 cm x 8-10 mm, the valves reddish-brown, glutinously lustrous, sometimes resin-dotted, smooth or remotely verruculose; seeds (poorly known) compressed- obovoid, ±5 x 3-3.2 mm, the testa black, lustrous, finely cross-crackled, faintly lineolate-pitted.

    Outcrops, ledges of sandstone cliffs, and on sands or sandy gravels along streams, occasionally in rocky cerrado or forest margins, regenerating from fire, 1050-1400 m, sometimes locally plentiful, s.-centr. Serra do Espinhaço in Minas Gerais, collected repeatedly within a circumference of 40 km from Diamantina, thence s. to Serro and the upper Sao Antonio; somewhat isolated to the s.-e. on Serras de Caraça and Ouro Preto. — Fl XII-VII, perhaps intermittently through the year.

    Among the glutinous cassias characterized by minute stipules and complete suppression of villi and setae (but cf. an individual exception described below), C. hedysaroides is distinguished by its oblong, basally symmetrical leaflets which become when dry dull olivaceous and not at all sticky above but varnished and resin-dotted beneath. The leaflets thus appear reversed, the ordinary dorsiventral contrast in the group being between a lustrous upper face contrasting with a dull lower one.

    In spite of a compact range, C. hedysaroides is subject to considerable variation in stature, and in number, size, and texture of the leaflets. The form common around Diamantina is a bushy shrub of broad outline, mostly 1-2.5 m tall, with 3-5 or 6 pairs of firm, thick-textured leaflets, each penninerved with about 4-8 pairs of major secondary nerves. On occasional robust plants or perhaps robustly vegetating branches of individual plants the leaflets may rise in number to 8 pairs without any other accompanying difference. It is to this firm-leaved form that Harms attached the manuscript epithet vernicifolia (or perhaps verniciflua as appears on the labels) which enters the literature as a nomen nudum in Glaziou's Liste. An individual variant (Irwin 2490) representing a population on an isolated outcrop but sympatric with the last (Irwin 2491) at a point 27 km southwest of Diamantina (in the Rio Velhas drainage), differs in an especially thrifty habit of growth and small leaves all composed of only 1-2 pairs of leaflets. From the vicinity of Serro south interruptedly to Ouro Preto C. hedysaroides appears to be exclusively represented by populations characterized by leaflets relatively ample and thin-textured, though not different in number or venation from those prevalent around Diamantina. Much of the material collected by the early travellers in Minas (Riedel, Miers, St. Hilaire) and indeed the type- collection of C. hedysaroides which came from the upper Rio Sao Antonio south of Serro is of this type; but in many cases neither the localities nor the stature of the plants were accurately recorded, and the patterns of dispersal are still unclear. In Serra de Cara^a at the southernmost limit of the known range, there is an arborescent population of C. hedysaroides with thin leaflets (Irwin 2508); but probably not all plants with thin leaflets attain treelet stature. A third variant, characterize by ample elliptic leaflets of thin texture but different again in the high number (up to 14) pairs of major secondary veins, has been encountered four times on the Mendanha road 18-19 km northeast of Diamantina (Irwin 2473; Irwin & al. 22674; Anderson 8382, Anderson & al. 8998), once as a shrub 2.5 m, twice as a slender tree 3-5 m tall. Finally not far distant from the last (18 km east of Diamantina, likewise on the headwaters of Rio Jequitinonha), there occurs a notable variant: (Irwin & al 27882) of the so-called "vernicifolia" type in which the distal branchlets and leafstalks are seen under magnification to be densely but microscopically puberulent. This mosaic of variants suggests an incipient stage of racial differentiation within C. hedysaroides, but one not sufficiently advanced to deserve taxonomic notice.