Cassia planifolia

  • Title

    Cassia planifolia

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia planifolia H.S.Irwin & Barneby

  • Description

    131.  Cassia planifolia Irwin & Barneby sp. nov., C. incurvatae Benth. affinis, caulibus simplicibus, petiolo abbreviato 1.5-9 nec 15-25 cm longo transverse alato-dilatato (nec subtereti anguste sulcato), foliolisque a summo petiolo erecto-adscendentibus (nec refractis) ambitu asymmetricis sed haud curvatis facillime distinquenda. — BRAZIL. Minas Gerais: among savannah grasses, 27 km s.-e. of Uberlandia on road to Altos Campos, 31.I.59 (fl, fr), H.S. Irwin 2527. — Holotypus, R; isotypi, F, K, NY, US. -- Plate 20.

    Subshrubs with several simple or almost simple stems up to 4-10 dm spreading and ascending from a xylopodium, glabrous but densely resin-dotted throughout, the narrowly thyrsiform inflorescence also minutely gland-verruculose and pustulate, the ample, greatly simplified foliage olivaceous, concolorous.

    Stipules minute, triangular-subulate, appressed to stem, 0.4-0.5 mm, tardily deciduous.

    Lvs ascending at ±45° to stem, shortly petioled, 4-10 cm; pulvinus not over 0.5 mm, scarcely differentiated; petiole (1.5-)3-8(-9) mm long, transversely dilated, narrowly wing- margined, shallowly convex ventrally, bluntly carinate dorsally; lfts 1 pair, ascending from tip of petiole and turned half face to face on a drum shaped, when dry wrinkled pulvinule less than 1 mm, in outline obliquely obovate, 3.5-8(-9) x 1.8-4.3(-5.5) cm, abruptly acuminu- late, callous-tipped but not mucronate, at base broadly obliquely cuneate-flabellate, the entire margin plane, the blades stiffly chartaceous, brownish-olivaceous, dull, on both sides densely resin-dotted and minutely densely pallid-papillate, the midrib and ±6-10 pairs of incurved- ascending, camptodromous secondaries elevated on both sides but more sharply so beneath, the tertiary connecting venules immersed above, beneath with a few faint irregular quaternary ones faintly raised but not forming a closed reticulum.

    Inflorescence a thyrse of 1-4 stiffly ascending, loosely 3-6-fld racemes axillary to the uppermost lvs together with one terminal and lf-opposed, the fls immersed in foliage or shortly exserted, the one expanded fl raised to level of next bud; bracts triangular-subulate, 1-1.5 mm, persistent; pedicels ascending, 1.4-2 cm, bracteolate 1-4 mm below calyx; bracteoles ±0.5 mm, tardily deciduous; buds ovoid-acuminate, densely pustulate; sepals submembranous, yellowish tinged with red, ovate-acuminate, 12-15 x 4-6.5 mm; petals yellow, four obovate-flabellate, up to 14-16 x 10-12 mm, the fifth obliquely obovate, firmer, coiled over androecium; ovary glutinous, verruculose; ovules 7-8.

    Pod narrowly oblong, straight, 35 x 7-8 mm, the livid-castaneous valves glutinous and resin-dotted; seeds compressed-obovoid or oblong-truncate, ±3.4-5 x 2-2.7 mm, the livid testa dull, transversely crackled and serially pitted lengthwise. — Collections: 3.

    Campo, very local on the Tijuco and Araguari forks of Rio Paranaiba (s.-e. of Uberlandia: Tijuco to Riachao Farinha Padre; Pratinha) in the Triangulo of Minas Gerais. — Fl. I-II.

    A functionally herbaceous cassia related to the almost sympatric and equally rare C. incurvata, but readily distinguished by the short, transversely dilated, ventrally shallow-convex petiole, and by the attitude of the obovate, asymmetric but scarcely curved leaflets, erect from the tip of the petiole and not deflected groundwards. The almost simple stem and consequently much simpler thyrsiform-paniculate inflorescence are also strikingly different in appearance. The habitally similar C. lavradioides, apparently endemic to Serra dos Cristais in southeastern Goias, resembles C. planifolia in the upswept bifoliolate leaves but, as shown in Plate 20, differs at first sight in the cuneate-oblanceolate outline of the leaflets.