Ischaemum aristatum

HABIT Perennial; caespitose; clumped loosely. Rhizomes short. Culms decumbent, or prostrate; 30–80 cm long; 1.2–2 mm diam. Culm-internodes terete, or channelled; 4–12(–25) cm long; smooth; distally glabrous. Culm-nodes glabrous, or pubescent. Lateral branches lacking, or sparse; arising from lower culm. Leaves cauline. Leaf-sheaths outer margin glabrous, or hairy. Ligule an eciliate membrane; 3–4 mm long; scarious; brown; truncate. Leaf-blades linear, or lanceolate; 5–30 cm long; 4–10 mm wide. Leaf-blade surface glabrous, or pilose; sparsely hairy. Leaf-blade margins smooth, or scabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2; paired; appressed back to back; 4–7 cm long; 5–8 mm wide. Rhachis fragile at the nodes; angular; scaberulous on margins; glabrous on margins, or pubescent on margins. Rhachis internodes columnar; 3–4 mm long; flat and forming a U or V shape with the pedicel in rear view. Rhachis internode tip transverse; cupuliform.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels columnar; glabrous, or puberulous.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; ovate; 4–6 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes; muticous, or 1-awned; with 0–3 mm long awn.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate, or rhomboid; dorsally compressed; 5–8 mm long; 2–2.3 mm wide; falling entire; deciduous with accessory branch structures. Spikelet callus glabrous; base truncate; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume elliptic; 1 length of spikelet; coriaceous; much thinner above; 2-keeled; keeled above; keeled laterally; winged on keel; winged broadly; winged above; 5 -veined. Lower glume primary vein scabrous. Lower glume lateral veins obscure; with cross-veins; intercarinal veins distinct; intercarinal veins 3 in number. Lower glume surface convex. Lower glume apex dentate; 2 -fid. Upper glume lanceolate; 1 length of spikelet; coriaceous; 1-keeled; keeled above; 5 -veined. Upper glume primary vein scabrous. Upper glume apex acute.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret ovate; hyaline; acute. Fertile lemma elliptic; hyaline; without keel. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; straight, or geniculate; 1–10 mm long overall; clearly exserted from spikelet, or not or scarcely exserted from spikelet; without a column, or with twisted column. Palea 1 length of lemma.

FLOWER Anthers 3; 2.5 mm long.

DISTRIBUTION Africa: western Indian ocean. Asia-temperate: China and eastern Asia. Asia-tropical: India, Indo-China, Malesia, and Papuasia. Pacific: southwestern, northwestern, and north-central.

NOTES Andropogoneae. Keng & Zhao 1996.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.