Cassia itambana

  • Title

    Cassia itambana

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia itambana Mart. ex Benth.

  • Description

    21.  Cassia itambana Martius ex Bentham in Martius, Fl. Bras. 15 (2): 151. 1870. — "Habitat in altis Serra da Itambe, prov. Minas Geraes: Martius." — Holotypus, Martius (Observatio) 1216 (4 sheets), M! = F Neg. 6241 = NY Neg. 8884. - Bentham, 1871, p. 566

    Amply leafy shrubs of rounded outline, with blackish old trunks, the young growth softly densely villosulous with fine erect whitish hairs, the young stems and lf-stalks shaggily villous with hairs up to 0.7-1 mm, the inflorescence in addition glutinously yellow-setose, the only slightly viscous foliage bicolored, the lfts paler and resin-dotted but not or obscurely setulose beneath.

    Stipules erect, linear-lanceolate or setiform, 4-7.5 mm, early dry and deciduous.

    Lvs widely spreading, 5-13(-17) cm, corasely petiolate; pulvinus a trifle dilated and discolored, ±2-2.5 mm; petiole 1-2.5(-3) cm, 0.7-1 mm diam, obscurely sulcate; rachis 1.5-5(-8.5) cm; lfts (2-)3-5 pairs, tilted somewhat forward, face upward, on densely villosulous discolored petiolule 1.2-2.5 mm, larger upward, in outline obliquely ovate to ovate-elliptic, acute to short- acuminate, mucronate by excurrent costa, (2-)2.5-6(-6.5) x (0.8-)1-2(-2.6) cm, at asymmetric base semicordate on proximal and rounded on distal side, the entire margin revolute, the blades chartaceous, above dull olivaceous or brownish-olivaceous, softly villosulous with fine erect hairs, beneath paler green, densely villous-hispidulous with straight hairs divergent and erect from all the veins, pallid-papillate between them, the midrib and 7-13 pairs of major secondaries above filiform, pallid, superficial, beneath sharply prominulous, the few connecting raised tertiary venules circumscribing large plane areoles.

    Inflorescence a leafy-bracteate panicle of simple or feebly branched, subsessile, pliantly spreading and drooping, laxly many-fld racemes elevated well above the foliage, the several fls simultaneously expanded standing far below the racemosely serial buds, the axis of the racemes becoming 8-15 cm; bracts submembranous, villosulous and minutely glandular, linear- lance-caudate, conduplicate, 3-8 mm, early dry, brown, caducous; pedicels slender ascending ±12-15 mm, bracteolate 1.5-5.5 mm below calyx; bracteoles resembling bracts, 2.5-4 mm, caducous; buds ovoid, sharply long-acuminate, thinly pilosulous and sometimes remotely setulose; sepals reddish, narrowly ovate- to lance-acuminate 9.5-12 x 2.7-4.2 mm; petals yellow, rather narrowly ascending, 4 subhomomorphic obovate-cuneate 14.5-17 x 6.5-9.5 mm, the dimidiately incurved fifth one slightly longer, incurved over androecium, the margin crenulate; ovary densely gray-pilosulous and finely viscid-setulose. — Collections: 5.

    Rocky cerrado and gallery margins, ±900-1000, perhaps 1400 m, very local but abundant where found, known only from high on e. slope of s. Serra do Espinhapo between 18° and 19° 30' S, from 3 collections without mature flowers from points 13 and 18 km e. of Diamantina, and from the type locality (cf. discussion). — Fl. IV—V.

    A handsome, free-flowering cassia, perhaps related to C. sophoroides, which is similar in the feebly viscid vesture and many-flowered, pliant racemes already elongate in bud, but notably different in the petioled leaves and acuminate flower-buds. These sharply pointed buds recall C. bracteolata, a near neighbor on the headwaters of Rio Jequetinonha, different in pubescence, more numerous and shorter, highly glutinous leaflets, small flowers, and characteristic petaloid bracteoles.

    The type locality of C. itambana is not altogether settled, owing to ambiguity between the Pico da Itambe, climbed by Martius in the first week of June 1818, and the Serra da Itambe which he and Spix ascended about a month earlier, en route between Ouro Preto and Tejuco. The Pico da Itambe or Itambe da Villa do Primcipe is the great isolated mountain standing off to the east of the crest of Serra do Espinhaço near 18° 25' S, whereas Serra da Itambe is an easterly spur of the same major chain lying nearly one degree latitude to the south, near the present Itambe do Mato Dentro. The only modern specimens of C. itambana that we have seen, unfortunately collected in young bud only, come from points east of Diamantina quite close to Pico da Itambe, but far distant from Serra da Itambe. While we believe them conspicific with the type, they differ in their 3-5 (not exactly 3)-yoked leaflets as well as in minor points of vesture and coloration. Until flowering specimens matching those of Martius can be obtained from a precise locality and mature ones of the populations east of Diamantina become available for comparison, the true range of C. itambana and the racial situation within it will remain in a cloud of speculation.