Echinochloa polystachya

HABIT Perennial. Basal innovations intravaginal. Culms decumbent; 100–300 cm long; 7–15 mm diam.; spongy; rooting from lower nodes. Culm-nodes swollen; glabrous, or pubescent. Lateral branches ample. Leaf-sheaths glabrous on surface, or hispid; with tubercle-based hairs. Ligule a fringe of hairs; 2–4 mm long. Leaf-blades 25–50 cm long; 20–35 mm wide. Leaf-blade midrib conspicuous. Leaf-blade surface glabrous. Leaf-blade margins spinulose.

INFLORESCENCE Inflorescence composed of racemes.

Racemes numerous; borne along a central axis; unilateral; 2–11 cm long. Central inflorescence axis 15–30 cm long. Rhachis subterete; ciliate on margins. Spikelet packing crowded; 4 -rowed. Raceme-bases brief; pilose.

Spikelets in threes. Fertile spikelets sessile and pedicelled; subequal. Pedicels 0.5–1 mm long; scabrous; tip discoid.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; gibbous; cuspidate; 4.5–6 mm long; falling entire.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume ovate; clasping; 1.9–4.2 mm long; 0.4–0.75 length of spikelet; without keels; 5–7 -veined. Lower glume surface scabrous. Lower glume margins ciliate. Lower glume apex cuspidate. Upper glume ovate; 1 length of spikelet; membranous; without keels; 5–7 -veined. Upper glume surface hispidulous; hairy on veins. Upper glume apex cuspidate; muticous, or awned; 1 -awned. Upper glume awn 0–7.5 mm long.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 5 -veined; hispidulous; cuspidate; muticous, or awned. Awn of lower sterile floret 2–15 mm long. Palea of lower sterile floret 1 length of lemma; scabrous; adorned on keels. Fertile lemma elliptic; gibbous; 2.5–5 mm long; indurate; much thinner above; shiny; without keel. Lemma margins involute. Lemma apex obtuse; laterally pinched. Palea reflexed at apex; indurate.

FLOWER Anthers 3; 1.5–3.6 mm long; orange.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION Asia-tropical: Papuasia. Australasia: Australia. North America: south-central USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, northern South America, western South America, Brazil, and southern South America.

NOTES Paniceae. Fl Costaric 1994.

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