Ischaemum fluviatile

HABIT Perennial. Culms prostrate; weak; 25–50 cm long. Leaf-sheaths loose; 5–10 cm long; longer than adjacent culm internode; glabrous on surface. Leaf-sheath auricles erect. Ligule an eciliate membrane; 2.5 mm long. Leaf-blade base with a false petiole. Leaf-blades 10–20 cm long; 4–8 mm wide. Leaf-blade surface glabrous, or pilose; sparsely hairy; hairy abaxially. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 2; paired; appressed back to back; 5–6 cm long. Rhachis fragile at the nodes; angular; ciliate on margins. Rhachis internodes oblong; 5 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; 2.5 mm long; ciliate.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; elliptic; laterally compressed; 6.6 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; winged on keels; smooth; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 6.6 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pubescent; base truncate; inserted.

GLUMES Glumes dissimilar; exceeding 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; 9 -veined. Lower glume lateral veins with cross-veins. Lower glume surface convex; muricate; rough on flanks; pubescent; hairy below. Lower glume margins ciliate. Upper glume ovate; 1 length of spikelet; chartaceous; 1-keeled; 7 -veined. Upper glume lateral veins with cross-veins. Upper glume apex acuminate; muticous.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret lanceolate; 5.4 mm long; hyaline; 3 -veined; acuminate. Palea of lower sterile floret 5.2 mm long. Fertile lemma lanceolate; 5.2 mm long; hyaline; without keel; 3 -veined. Lemma apex lobed; 2 -fid; incised 0.75 of lemma length; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 21 mm long overall; with twisted column. Column of lemma awn glabrous. Palea 4.2 mm long.

FLOWER Anthers 3; 2.8 mm long; purple. Stigmas purple.

DISTRIBUTION Asia-tropical: Malesia.

NOTES Andropogoneae. Gilliland 1997.

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