Ischaemum thomsonianum

HABIT Annual. Culms decumbent; 20–100 cm long; rooting from lower nodes. Culm-nodes bearded. Leaf-sheaths keeled. Ligule a ciliolate membrane. Leaf-blade base simple, or broadly rounded. Leaf-blades lanceolate; 2–15 cm long; 4–10 mm wide. Leaf-blade surface pilose; sparsely hairy, or moderately hairy, or densely hairy. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2; paired, or digitate; appressed back to back; 3–10 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; 3–3.5 mm long; 1 length of internode; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; lanceolate, or oblong; laterally compressed; 5–6 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; winged on keels; 11–15 -veined; awned; one glume awned. 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 elliptic; dorsally compressed; 5–6 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus cuneate; 1–2 mm long; bearded; base truncate; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate, or ovate; 1 length of spikelet; coriaceous; much thinner above; 2-keeled; keeled above; keeled laterally; winged on keel; winged narrowly; winged near apex; 11–15 -veined. Lower glume surface flat; impressed above. Lower glume apex dentate; 2 -fid. Upper glume lanceolate, or ovate; chartaceous; 1-keeled; winged on keel; winged near apex; 5 -veined. Upper glume margins ciliolate. Upper glume apex dentate; 2 -fid; awned; 1 -awned. Upper glume awn 1–2 mm long.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret ovate; 4–5 mm long; membranous; 3 -veined; ciliolate on margins; fringed above; acute, or acuminate. Fertile lemma oblong; 4–4.5 mm long; membranous; without keel; 3 -veined. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 10–15 mm long overall; with twisted column. Column of lemma awn 4–5 mm long; glabrous.

FLOWER Anthers 3; 2–3 mm long.

DISTRIBUTION Asia-temperate: China. Asia-tropical: India and Indo-China.

NOTES Andropogoneae. Nair 1993.

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