Pteronia membranacea L.F.

Branches more or less quadrangular, glabrescent; branchlets terete, densely mealy-puberulous. Leaves opposite, oblong-lanceolate or slightly oblanceolate, acute, slightly narrowed to a broad base, 8-11 mm long, about 3 mm broad, rigidly chartaceous, distinctly keeled below, not visibly nerved above, densely puberulous on both surfaces. Heads solitary, terminal, sessile, turbinate, 25 cm long, 1-5 cm in diameter, about 13-flowered. Involucral bracts 6-seriate, the outermost two opposite, ovate, cuspidate, 5 mm long, 3 mm broad, strongly keeled, with broad membranous hyaline margins, the latter not extending to the apex, minutely puberulous on the outside; remainder of bracts with the hyaline margins continued to the apex, the innermost series oblong-lanceolate, rounded at the apex, about 1 x 8 cm long and 5 mm broad, with a broad pointed green middle portion and membranous slightly jagged hyaline margins which are broadest near the apex. Receptacle flat, shortly and rigidly setose. Corolla-tube 1 cm long, cylindric, broader in the middle, with a sub-campanulate limb, glabrous; lobes lanceolate, subobtuse, 2 mm long. Anthers 4.5 mm long, linear, with an acute lanceolate apex. Achenes 3.5 mm long, densely long-villous, contracted at the apex into a distinct glabrous neck. Pappus yellowish-brown when dry, slightly shorter than the corolla-tube, inserted on a distinct annulus.