Ischaemum byrone (Trin.) Hitchc.

Map

Inflorescence

image credit: Forest & Kim Starr

Plant

image credit: Forest & Kim Starr

Spikelets

Description

Stoloniferous perennials; culms erect from a decumbent base, 4-8 dm tall, glabrous, nodes sparsely long-pilose. Sheaths glabrous or occasionally long-pilose near base with hairs up to 7 mm long, the uppermost sheaths often inflated, auricles firm, 3-4 mm long; ligule prominent, membranous at the center, ovate to truncate, 1.5-3 mm long; blades flat, 7-20 cm long, 3-5 mm wide, glabrous, the uppermost much reduced, apex attenuate. Racemes yellow to yellowish brown, 2(3) per inflorescence, often partially included within the inflated sheath, digitate, 4-10 cm long, rachis joints triangular, 3-4 mm long, ca. 1 mm in diameter, pilose at base and along margins toward apex, concave at apex; sessile spikelet 6-7 mm long (excluding awns), the hairs at base ca. 1/2 as long, first glume oblong, ca. 6 mm long, flat on the back, indistinctly nerved, scaberulous, pilose on the back with hairs up to 4 mm long, apex bidentate, the teeth short-awned, the awns 0.5-1 mm long, second glume 6-7 mm long, keeled, scaberulous toward apex but otherwise glabrous, nerveless or weakly nerved, apex tapering to a scabrous awn 5-7 mm long, first lemma hyaline, about as long as first glume, second lemma hyaline, 5-nerved, apex bidentate, awned from between the teeth, the awn 24-26 mm long, tightly twisted up to the first bend (ca. 5 mm); pedicellate spikelet 5-6 mm long, pedicel ca. 3 mm long, ca. 1 mm in diameter and triangular like the rachis joint, long-pilose on 1 of the angles, the others ciliate, first glume ca. 6 mm long, distinctly 5-nerved, rounded on the back, scaberulous, sparsely pilose on back with hairs up to 3 mm long, apex bidentate, with an awn ca. 1 mm long, second glume ca. 6 mm long, 7-nerved, scaberulous, lower half densely pilose with hairs up to 4 mm long, keeled, the keel scabrous, apex with an awn 2-3 mm long, first lemma hyaline, 4-5 mm long, 3- nerved, apex bidentate, awned from between the 2 teeth, the awn reddish brown, 1.5-2 cm long, twisted, glabrous below first bend, scabrous above it, straight. Caryopsis golden, ovate, ca. 3 mm long.
(Description source: O’Connor, P.J. 1990. Poaceae, pp. 1481–1604. In: Wagner W.L., Herbst D.R. & Sohmer S.H. (eds.)., Manual of the flowering plant of Hawaiʻi. Vol. 2. University of Hawaii Press & Bishop Museum Press, Honolulu )