Cassia crenulata

  • Title

    Cassia crenulata

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia crenulata Benth.

  • Description

    112.  Cassia crenulata Bentham in J. Bot. (Hooker) 2: 80. I840. — "...from Pohl's Brazilian collection." — Holotypus, Pohl 5297, collected probably VII. 1819, in "Serra San Feliz prope Correio", i.e. on a north spur of Chapada dos Veadeiros in mun. Cavalcante, Goias, K (hb. Benth.) ! = IPA Neg. 1041 = NY Neg. 1489, 6739; isotypi, NY, W! — Bentham, 1870, p. 140; 1871, p. 562.

    Shrubs up to 1.5 m, the old trunks clad in furrowed bark, branching distally into a shortly exserted, partly leafy-bracteate panicle of few-flowered racemes, glabrous throughout, the young branchlets, the axes of inflorescence, and buds all resinously viscid and at least thinly verruculose (but nowhere setulose), the ample chartaceous pallid, often pink-tinged and glaucescent foilage little dorsoventrally differentiated, the plane lfts eglandular on the faces but charged around the margins with sessile, shallowly recessed, resin-exuding warts, becoming minutely crenulate.

    Stipules obsolete, represented by gum-exuding spots, the gum often hardening into axillary granules of amberlike resin.

    Lvs widely spreading on flexous leafstalks, 8-16 cm, petioled; pulvinus narrowly ovoid, dilated, 2—3.5 mm, coarsely wrinkled when dry; petiole 1.6-4-(4.5) cm, at middle 0.8-1.3 mm diam, obscurely 2-carinate and very shallowly or obscurely sulcate ventrally; rachis (3-)4-8 cm; lfts 4-6 pairs, widely spreading-ascending from the rachis, tilted half face to face on cylindric, transversely rugulose pulvinules 2-3.5 mm, slightly accrescent upward, in outline broadly to narrowly obovate obtuse, 2.7-5.5 (-7) x 1.5-3.3 cm, at oblique base rounded on both sides or on the distal side broadly cuneate, the plane margin glandular-crenulate, the blades stiffly chartaceous concolorous, opaquely pallid-olivaceous often tinged with pink and at maturity subglaucescent, the straight or very slightly incurved midrib and (5-)6-8 pairs of major secondary veins subequally prominulous both sides, the midrib slightly more so dorsally, the tertiary connecting venules either faintly raised to form an irregular mesh of areoles up to 1-1.5 mm diam. or these almost immersed.

    Inflorescence a complexly branched ovoid or subcorymbosely flat-topped panicle of 3-7-fld racemes, ±1-2 dm long and about as broad, the lower branchlets leafy-bracteate, the distal ones minutely bracteate, the axis of individual racemes up to 6 cm, mostly less, the one expanded flower of each elevated to level of buds; bracts deltate-triangular, 0.6-1 mm long, persistent, usually coated in resin; pedicels 13-22(-25) mm, bracteolate 0.5-2 mm below calyx; bracteoles scarcely smaller, persistent; buds ovoid-ellipsoid, obtuse, densely verruculose and glutinous.

    Sepals (probably reddish) firm except for membranous margins, widely expanded at anthesis, elliptic to elliptic-oblanceolate, obtuse, 11-13.5 x 3.5-6 mm; petals yellow, the four plane ones loosely incurved-ascending, f label late, contracted into a long cuneate claw, unequal (2 larger), the longest up to ±20-23 x 15-18 mm, the fifth falcately oblanceolate, shorter, coiled; ovary densely glutinous-verruculose; ovules 5-7.

    Pod (not seen ripe) ±4 x 0.75 cm, the valves atrocastaneous, glutinously lustrous and glandular-verruculose; seeds unknown. — Collections: 3.

    On outcrops in cerrado, near 1000 m, apparently local, known only from three stations on the headwaters of Rio Tocantins in s.-centr. Goias (Serra dos Pireneus and Chapada dos Veadeiros). — Fl VII-VIII.

    A shrubby, paniculately branching cassia, completely hairless but with stickily resinous inflorescence, notable for the glandular-crenulate leaf-margins, a character shared with C. fragilis and C. dentata. It differs from both of these in the more numerous (4-6) pairs of broad leaflets borne on stiffer and coarser, scarcely pliant and not at all pendulous leafstalks, and further from C. fragilis, similar in length of pedicels, in the substanially larger flowers. The partly sympatric C. brachyclada, also glabrous and glutinously verruculose in the inflorescence, is a squatly sturdy undershrub with few-leaved, simple stems thickened and corky at base; its smooth, stiffer leaflets are turned edgewise to the noon sun and are merely livid-glandular but not crenulate around the margins. This also differs from C. crenulata in the development of small but definite stipules and in the well-exserted leafless panicle of racemes.

    Bentham (1871, p. 562) placed C. crenulata next beside C. polystachya, latterly transferred to sect. Apoucouita (Irwin, 1967, p. 113), in an artificial subgroup of ser. Baseophyllum characterized by several pairs of leaflets. The petiolar glands of ser. Baseophyllum and sect. Apoucouita are true secretory organs, composed of structurally modified tissues. The supposed glands of C. crenulata appear, on the contrary, to be merely scars of insect damage, very irregular in their placement and sometimes lacking, moreover to be found not only on the ventral but also the lateral and rarely the dorsal faces of the leafstalk.