Ischaemum polystachyum

HABIT Perennial. Rhizomes elongated. Culms decumbent, or prostrate; 30–150 cm long; without nodal roots, or rooting from lower nodes. Culm-nodes pubescent. Ligule an eciliate membrane; 2.5 mm long. Leaf-blades 5–25 cm long; 3–20 mm wide. Leaf-blade surface glabrous, or pubescent.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2–5(–8); paired, or digitate; unilateral; 3–15 cm long. Rhachis fragile at the nodes; angular; ciliate on margins. Rhachis internodes cuneate; flat and forming a U or V shape with the pedicel in rear view, or flat and forming a U or V shape with the pedicel in rear view and with a basal circular pore between internode and pedicel. Rhachis internode tip transverse; cupuliform.

Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels cuneate; 1 length of internode; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; elliptic; laterally compressed; 4–7 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; 7–9 -veined; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes; 1-awned.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate, or oblong; dorsally compressed; 4–7 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 1–1.5 mm long; bearded; base obtuse; inserted.

GLUMES Glumes dissimilar; reaching apex of florets; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; chartaceous; much thinner above; 2-keeled; keeled above; keeled laterally; wingless, or winged on keel; winged above; 5–9 -veined. Lower glume surface convex; glabrous, or pilose, or villous. Lower glume apex entire, or dentate; 2 -fid. Upper glume lanceolate; 1 length of spikelet; chartaceous; 1-keeled; keeled above; 3–5 -veined. Upper glume apex acuminate.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret lanceolate; 1 length of spikelet; membranous; 3–5 -veined; acute. Fertile lemma oblong; 4–6 mm long; membranous; without keel; 3 -veined. Lemma margins ciliate. Lemma apex lobed; 2 -fid; incised 0.5 of lemma length; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 5–20 mm long overall; with twisted column. Column of lemma awn glabrous. Palea 1 length of lemma.

DISTRIBUTION Africa: west tropical, west-central tropical, northeast tropical, east tropical, southern tropical, south, and western Indian ocean. Asia-temperate: China. Asia-tropical: India, Indo-China, Malesia, and Papuasia. Australasia: Australia. Pacific: southwestern and northwestern.

NOTES Andropogoneae. FTEA.

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