Perennial with long creeping, branched, scaly rhizomes with a few long internodes. Basal leaves vigorous, with coriaceous, sheaths, which finally disintegrating into fibers; ligule short; blades erect, linear-lanceolate, gradually attenuate downwards, and sometimes reduced to a stout midrib, upwards gradually tapering into an acute, usually hard and sharp point, the older blades hard with serrate, silicous edges. lnflorescence a silky panicle with inarticulate axis, branched on all sides, very dense and contracted, spike-like during anthesis, afterwards more spreading but still narrow, silvery white, creamy or light-yellow. Spikelets in unequally pedicelled pairs, articulate with wide, excavated apex of pedicels, oblong, muticous, at base with dense crown of glossy white hairs, the hairs much longer than spikelet, at first erect, afterwards spreading, glumes subequal, thin, 3-9-nerved, rarely nerveless, long-hairy in lower half; lemma smaller, hyaline, very thin, except at base, 1-nerved or nerveless; lower palea absent; upper lemma sometimes wanting; upper palea conduplicate, broad, hyaline, nerveless, usually embracing bisexual flower; lodicules wanting; stamens 2 or 1; styles 2, connate at base, the stigmas long and narrow, exserted apically. Caryopsis oblong, free; embryo 1/2 as long as caryopsis of longer.
About ten species distributed in tropical and subtropical regions; one troublesome weed species.
I. cylindrica var. major is very common in sunny exposed areas in Taiwan.