Cassia incurvata

  • Title

    Cassia incurvata

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia incurvata Benth.

  • Description

    134.  Cassia incurvata Bentham in Martius, Fl. Bras. 15 (2): 137. 1870.

    Amply leafy subshrubs up to 5-10 dm, the stems rising stiffly erect from a xylopodium, below middle simple, leafless, up to 5 mm diam, repeatedly branching upward, the slender lateral branches all again branched and going out into short, few-fld racemes, glabrous and glutinous throughout, the stems and subconcolorous foliage densely resin-dotted, the inflorescence and pod glandular-verruculose, nowhere setulose.

    Stipules minute, less than 0.5 mm, glandiform and deciduous, or obsolete.

    Lvs 5.5-10(-11) cm long, petiolate; pulvinus oblong, dilated, livid, 2-4 mm, when dry wrinkled and transversely furrowed; petiole stiffly ascending at 35°-45° to vertical, 1.5-2.5 cm, narrowly grooved ventrally; rachis 0, except for the minute appendage between the lfts; lfts 1 pair, turned, on dilated pulvinule 2-3 mm, outward and downward through nearly 90° from tip of petiole and tilted edgewise, the curved midribs hence directed obliquely groundward and the proximal basal curve of the margin directed to the meridian, in outline obliquely lance-caudate or falcately semi-ovate, 3-9 x 0.9-5 cm, at apex acuminulate or subcaudate, the tip callous but not mucronate, at the highly asymmetric base deeply cordate to cuneately obtuse on proximal and narrowly cuneate on distal side, the entire or minutely undulate margins plane, the blades stiffly chartaceous, olivaceous, above glutinously sublustrous, beneath brownish, on both sides densely resin-dotted and sometimes sparsely verruculose along the veins, the eccentric, incurved-ascending midrib with 8-20 pairs of secondary connecting tertiary and some faint reticular venules all obtusely equally prominulous on both sides.

    Racemes axillary and terminal to all the branchlets, mostly leafy-bracteate but some of the uppermost not so, laxly 3-9-fld, the axis 1-5(7.5) cm, the fls mostly raised ± to level of lvs and the one expanded fl to or beyond level of the next bud; bracts narrowly triangular or subulate, thick, verruculose, ± 0.5-1 mm; pedicels ascending, 1-2.1 cm, bracteolate 1-3.5 mm below calyx; bracteoles resembling bracts, hardly smaller, tardily deciduous; buds ovoid long-acuminate, densely resinous and glandular-verruculose; sepals lance-acuminate, 12-16 x 3.5-6 mm; petals (little known) up to 14-20 mm; ovary densely verruculose; ovules 6-7.

    Pod linear-oblong, slightly arched forward, 2.3-4 x 0.7-0.9 cm, the chartaceous nigrescent valves glutinously resinous and verruculose; seeds 4.3-5 x 3-3.2 mm, the testa black, crackled, faintly lineolate-pitted.

    A species of highly localized dispersal on detached morros around the southwestern edge of the Planalto, consisting of five or six known populations between which exchange of pollen must have been impossible for millenia past. Two major variants have developed in isolation, one in and near the Triangulo of southwestern Minas, the other distant nearly 400 km in extreme southern Minas, about 50 km north of the common boundary point with states of Rio de Janeiro and Sao Paulo.

    1. Lfts obliquely semi-ovate-acuminate, 2 to less than 3 times as long as wide, at base broadly deltate, the proximal basal margin forming an angle of 90° or more with the midrib; petals ±16 mm long; Triangulo of s.-w. Minas Gerais, on forks of Rio Paranaiba, and immediately adjoining Goias.

    134a. var. incurvata

    1. Lfts obliquely lance-caudate, more than 3 up to 4 times as long as wide, cuneate at base, the proximal basal margin forming an angle of ± 45° with midrib; petals 18-20 mm long; Morro de S. Tome das Letras, 45° W, 21° 45 S.

    134b. var. zanclodes