Ischaemum commutatum

HABIT Perennial. Culms decumbent, or rambling; 30–100 cm long; rooting from lower nodes. Culm-nodes glabrous. Lateral branches ample. Leaf-sheaths outer margin hairy. Leaf-sheath auricles erect. Ligule an eciliate membrane; 1–5 mm long. Leaf-blade base simple, or broadly rounded; with a false petiole (lower leaves); petiole 0.5–6 cm long. Leaf-blades lanceolate; 4–15 cm long; 8–15 mm wide. Leaf-blade surface hirsute. Leaf-blade margins cartilaginous; scabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2; paired; appressed back to back; 3–6 cm long. Rhachis fragile at the nodes; angular; ciliate on margins. Rhachis internodes oblong; 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 oblong; 3–4 mm long; 1 length of internode; ciliate; hairy on one margin.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; ovate; asymmetrical; laterally compressed; 5 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; winged on keels (1 keel). Companion sterile spikelet lemmas 2; enclosed by glumes; muticous.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 5–6.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus glabrous, or pubescent; base truncate; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; coriaceous; 2-keeled; keeled all along; keeled laterally; wingless, or winged on keel; winged narrowly; 11–13 -veined. Lower glume surface flat; smooth, or muricate; rough on flanks. Lower glume apex acute. Upper glume lanceolate; coriaceous; 1-keeled; 3 -veined. Upper glume margins ciliolate. Upper glume apex acuminate.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret lanceolate, or oblong; membranous; 3–5 -veined; ciliate on margins; fringed above; acuminate. Fertile lemma oblong; 4.5–5 mm long; membranous; without keel. Lemma margins ciliolate; hairy above. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 10–15 mm long overall; with twisted column. Column of lemma awn glabrous.

FLOWER Anthers 3; 1–3 mm long.

DISTRIBUTION Asia-tropical: India.

NOTES Andropogoneae. Nair 1993.

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