Andropogon arenarius

HABIT Perennial; caespitose. Basal innovations intravaginal. Culms 60–80 cm long. Culm-nodes glabrous. Leaf-sheaths 8–18 cm long; glabrous on surface. Ligule an eciliate membrane; 1–1.8 mm long; truncate. Leaf-blades 9–37 cm long; 2–3 mm wide; stiff. Leaf-blade surface glabrous.

INFLORESCENCE Synflorescence compound; paniculate. Inflorescence composed of racemes; terminal and axillary; subtended by a spatheole; embraced at base by subtending leaf. Spatheole lanceolate; 6–8 cm long.

Racemes 2–3; paired, or digitate; 3–6 cm long. Rhachis fragile at the nodes; villous on margins. Rhachis hairs 10–16 mm long. Rhachis internodes filiform; 0.66 length of fertile spikelet. Rhachis internode tip transverse; cupuliform; with simple rim.

Spikelets ascending; in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; villous; with 10–16 mm long hairs.

STERILE SPIKELETS Companion sterile spikelets well-developed; containing empty lemmas, or male; lanceolate; dorsally compressed; 5–7 mm long; longer than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; glabrous; acute; muticous. Companion sterile spikelet lemmas enclosed by glumes.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 3.5–5 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; coriaceous; 2-keeled; keeled laterally. Lower glume surface concave. Upper glume linear; coriaceous; 1-keeled. Upper glume muticous.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret oblong; hyaline. Fertile lemma lanceolate; hyaline; without keel. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 2–5.5 mm long overall; with a straight or slightly twisted column. Column of lemma awn 0.5–0.8 mm long; glabrous.

FLOWER Anthers 3; 0.8 mm long.

FRUIT Caryopsis 1.2–2.4 mm long; dark brown.

DISTRIBUTION South America: Brazil and southern South America.

NOTES Andropogoneae. Herve & Valls 1995.

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