Andropogon virginicus

HABIT Perennial; caespitose. Culms erect; 50–100 cm long. Culm-nodes glabrous. Leaf-sheaths keeled; glabrous on surface, or hispid; outer margin glabrous, or hairy. Ligule a ciliolate membrane. Leaf-blades flat, or conduplicate; 10–20 cm long; 2–5 mm wide. Leaf-blade surface glabrous.

INFLORESCENCE Synflorescence compound; lax. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; embraced at base by subtending leaf. Spatheole lanceolate; 2.5–6 cm long.

Racemes 2–5; paired, or digitate; sinuous; 2–3 cm long. Rhachis fragile at the nodes; plumose on surface; plumose on margins. Rhachis hairs 5–10 mm long. Rhachis internodes filiform. 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; curved; plumose; with 5–10 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets represented by barren pedicels.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; dorsally compressed; 2.5–4 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus 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; hyaline. Fertile lemma lanceolate; hyaline; without keel. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; straight; 10–26 mm long overall. Palea absent or minute.

FLOWER Anthers 3.

DISTRIBUTION Asia-temperate: Caucasus and eastern Asia. Australasia: Australia and New Zealand. Pacific: south-central and north-central. North America: north-central USA, northeast USA, southwest USA, south-central USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, western South America, and Brazil.

NOTES Andropogoneae. Gr Texas 1993.

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