Echinochloa chacoensis

HABIT Annual, or perennial; short-lived. Culms erect, or geniculately ascending; robust; 40–140 cm long; without nodal roots, or rooting from lower nodes. Leaves cauline. Leaf-sheaths loose, or inflated; glabrous on surface. Ligule a fringe of hairs; 1.5–3.5 mm long. Leaf-blade base simple, or broadly rounded, or cordate. Leaf-blades 15–30 cm long; 5–20 mm wide. Leaf-blade surface pilose; sparsely hairy. Leaf-blade margins scabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 5–13; borne along a central axis; unilateral; 2–5 cm long; simple. Central inflorescence axis 5–20 cm long. Rhachis narrowly winged; angular; 0.5–0.7 mm wide; scabrous on margins. Spikelet packing irregular; 4 -rowed.

Spikelets in pairs. Fertile spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; gibbous; cuspidate; 3.5–5 mm long; falling entire.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume ovate; clasping; 0.3–0.4 length of spikelet; membranous; without keels; 5 -veined. Lower glume apex acute. Upper glume ovate; 1 length of spikelet; membranous; without keels; 5 -veined. Upper glume surface hispidulous. Upper glume apex acuminate.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 3–5 -veined; hispidulous; acuminate. Fertile lemma orbicular; gibbous; 3–4.5 mm long; indurate; much thinner above; shiny; without keel. Lemma surface smooth, or striate. Lemma margins involute. Lemma apex apiculate. Palea reflexed at apex; indurate.

FLOWER Anthers 3.

DISTRIBUTION South America: western South America.

NOTES Paniceae. Renvoize 1996.

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