Cassia trachycarpa

  • Title

    Cassia trachycarpa

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia trachycarpa Vogel

  • Description

    8.  Cassia trachycarpa Vogel, Syn. Gen. Cass. 52. & in Linnaea 11: 698. 1837, descr. ampliata 1837.

    Viscid-glandular shrubs 1-2 m with nigrescent, leafless trunks paniculately branching distally into a rounded crown of soft, ample foliage shortly surpassed by dense terminal racemes, variably pubescent with some combination of fine villi, setules, and coarse setae up to 2 mm long, the villi and longer setae sometimes absent but the stem distally and inflorescence usually, the pod always, ± setose, the foliage bicolored, pallid-papillate beneath.

    Stipules submembranous, ascending or spreading-recurved, narrowly lance-acuminate, (2-) 3-6 mm long, persistent or tardily deciduous.

    Lvs ascending and widely spreading on pliant tapering footstalks, petiolate, 4.5-12.5 cm, pulvinus slightly dilated, livid but otherwise scarcely differentiated, 1-5-3 mm; petiole 1 2-27(-31) mm, shallowly sulcate; rachis (2-)2.5-8 cm; lfts (3-)4-9 pairs, spreading face upward from rachis on livid, scarcely dilated petiolule 0.6-1 mm long, in outline varying from ovate to oblong- or obovate-elliptic, obtuse to short-acuminate, always sharply mucronate, (8-) 10-23 (-25) x 4-10.5 mm, at oblique base rounded on proximal and cuneate or cuneately rounded on distal side, the entire margin revolute, the blades (dry) submembrano-chartaceous, bicolored, above brown-olivaceous or nigrescent, dull, glabrous or thinly villosulous or sparsely setulose, beneath pallid-papillate, thinly hispidulous and setulose (setose) along the veins and sometimes also thinly villosulous between them, the midrib and (4-)5-8 pairs of filiform secondaries immersed above, beneath all prominulous or the secondaries sometimes obscurely so, the connecting tertiaries few, weak and immersed.

    Inflorescence of dense solitary racemes terminal to the branchlets, shortly exserted or raised only to level of foliage, the several simultaneously expanded fls disposed pseudocorymbosely in a flat-topped, moplike head, the axis lengthening after anthesis and becoming 6-20 cm; bractc submembranous, pallid or brownish, narrowly lance-acuminate or caudate, entire or 3-denticulate near middle 4-7 mm, becoming dry and tardily deciduous; pedicels narrowly ascending, crowded on axis, 13-30 mm, bracteolate 0.5-5 mm below calyx; bracteoles 1.5-3 mm, subpersistent; buds ovoid- acuminate, red-tinged, remotely setulose to hispid-setose and often in addition viscid-villosulous at base; sepals lance- to ovate-acuminate, 7-12 x 2-4.5 mm; petals yellow, four narrowly ascending at full anthesis, oblanceolate to spathulate-oblanceolate, of unequal length and width, the longest 9.5-16 x 3.7-6.5 mm, the fifth obliquely oblanceolate, coiled over androecium; ovary densely setose; ovules (5-)6-8.

    Pod linear-oblong, nearly straight, 2.5-4 x 0.6-0.85 mm, the firmly chartaceous, livid- castaneous valves nigrescent, glutinous but not villosulous, densely hispid-setose; seeds com- pressed-pyriform, 4.2-4.7 x 2.4-3.1 mm, the testa livid-castaneous or blackish, highly lustrous, minutely crackled and faintly pitted in serial rows.

    In habit and foliage resembling some forms of the partly sympatric C. cathartica, but very different in the form of the densely many-flowered, normally racemose, not leafy-bracteate inflorescence. In C. cathartica only one or two flowers are expanded on a given day; here several reach maturity simultaneously and together with the buds form a flat-topped or low-convex false corymb above such faded flowers as there may be below.

    Within its comparatively small range C. trachycarpa shows considerable variation in number and size of leaflets and especially in the pubescence of the foliage and stems. The three component types of vesture, fine villi, setules, and long hispid setae, vary in proportion from one race to another, the setae, especially in Minas, being sometimes absent, and the density of villi especially on the faces of the leaflets, being quite inconstant. The populations in southeastern Sao Paulo differ from those in Minas in their constantly fewer leaflets and smaller flowers, a combination of characters which permits the recognition of two varieties, each, however, about equally variable in size and pubescence of leaflets.

    1.  Fls relatively small, the longer sepals 6.5-8 mm, the longer petals 9.5-12 mm; lfts (3-)4-6 pairs; s.-e. Sao Paulo in valley of Rio Paraiba downstream from Sao Jose Campos.

    8a. var. trachycarpa

    1.  Fls larger, the longer sepals 9-12 mm, the longer petals 1 3-16 mm; lfts 6-9 (of some lvs at least 7) pairs; s. Minas Gerais, s-w.-ward from Belo Horizonte

    8b. var. acutifolia