Andropogon virgatus

HABIT Perennial; caespitose. Butt sheaths persistent and investing base of culm; with compacted dead sheaths. Basal innovations flabellate. Culms erect; 60–100 cm long. Ligule a ciliolate membrane. Leaf-blades flat, or conduplicate; 10–50 cm long; 2–4 mm wide; stiff.

INFLORESCENCE Synflorescence compound; fastigiate; 10–40 cm long. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; embraced at base by subtending leaf. Spatheole linear; 0.7–1.5 cm long; herbaceous. Peduncle pubescent above.

Racemes 1; single; 6–12 cm long. Rhachis fragile at the nodes; subterete; glabrous on margins. Rhachis internodes linear; 0.5–0.6 mm long. Rhachis internode tip transverse; flat; with simple rim.

Spikelets appressed; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; 0.5–0.6 mm long; glabrous; tip rectangular.

STERILE SPIKELETS Companion sterile spikelets well-developed; male; lanceolate; dorsally compressed; 2.4–3 mm long; as long as fertile; persistent. Companion sterile spikelet glumes chartaceous; muticous. Companion sterile spikelet lemmas enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 2.4–3 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus oblong; 0.5 mm long; glabrous; base truncate; attached transversely.

GLUMES Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of spikelet; coriaceous; 2-keeled; keeled above; keeled laterally. Lower glume primary vein scaberulous. Lower glume intercarinal veins absent. Lower glume surface flat. Lower glume apex acute. Upper glume lanceolate; coriaceous; 1-keeled; 1 -veined. Upper glume primary vein scaberulous. Upper glume lateral veins absent. Upper glume margins ciliolate. Upper glume apex acute.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; 1.5 mm long; 0.5 length of spikelet; hyaline; 2 -veined. Fertile lemma linear; 2 mm long; hyaline; without keel; 1 -veined. Lemma apex entire; muticous. Palea absent or minute.

FLOWER Anthers 3; 0.5–1.3 mm long.

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

NOTES Andropogoneae. WDC.

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