Andropogon bicornis

HABIT Perennial; caespitose. Culms erect; 150–250 cm long; 4–6 mm diam. Culm-internodes with small lumen. Culm-nodes glabrous. Lateral branches ample. Leaf-sheaths keeled. Ligule a ciliolate membrane; 1–1.2 mm long. Leaf-blades 25–50 cm long; 2–6 mm wide. Leaf-blade surface glabrous. Leaf-blade margins scabrous.

INFLORESCENCE Synflorescence compound; paniculate (obovate); dense. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; embraced at base by subtending leaf. Spatheole linear; 3–4 cm long.

Racemes 2; paired; 2.5–3.5 cm long. Rhachis fragile at the nodes; plumose on surface; plumose on margins. Rhachis hairs 6–8 mm long. Rhachis internodes filiform; 2.5–3 mm long. Rhachis internode tip transverse; cupuliform; with simple rim.

Spikelets ascending, or spreading; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; 3–4 mm long; plumose; with 6–8 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets represented by barren pedicels, or rudimentary (except terminal); lanceolate; 0–1 mm long; shorter than fertile. Companion sterile spikelet glumes chartaceous; muticous.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 3–3.5 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 0.2 mm long; pilose; base obtuse; inserted.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; membranous; 2-keeled; keeled laterally. Lower glume intercarinal veins absent. Lower glume surface concave. Upper glume lanceolate; membranous; 1-keeled; 1 -veined. Upper glume lateral veins absent. Upper glume muticous.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 2–2.4 mm long; hyaline; 0 -veined; ciliate on margins. Fertile lemma lanceolate; 1.6–2.2 mm long; hyaline; without keel. Lemma apex entire; acute; muticous. Palea absent or minute.

FLOWER Anthers 3; 0.5–0.7 mm long; purple.

FRUIT Caryopsis with adherent pericarp; 1.6–2 mm long.

DISTRIBUTION North America: Mexico. South America: Mesoamericana, Caribbean, northern South America, western South America, Brazil, and southern South America.

NOTES Andropogoneae. Fl Costa Rica 1993.

ADDITIONAL CHARACTERS Terminal pedicelled spikelet larger than sessile.

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