Diarrhena americana

HABIT Perennial. Rhizomes elongated; scaly. Culms erect; 50–120 cm long. Ligule an eciliate membrane. Leaf-blades linear, or lanceolate; 25–50 cm long; 8–20 mm wide. Leaf-blade venation with obscure cross veins.

INFLORESCENCE Inflorescence a panicle.

Panicle open; lanceolate; 8–25 cm long.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 3–5 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 10–18 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes eventually visible between lemmas.

GLUMES Glumes persistent; dissimilar; shorter than spikelet. Lower glume lanceolate; 0.5 length of upper glume; cartilaginous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume ovate; 0.66 length of adjacent fertile lemma; cartilaginous; 1-keeled; 3–5 -veined. Upper glume apex acute.

FLORETS Fertile florets divergent; free at tip. Fertile lemma elliptic; 6–10 mm long; cartilaginous; much thinner on margins; without keel; rounded except near apex; 3 -veined. Lemma lateral veins convergent above. Lemma apex cuspidate; awned; 1 -awned. Principal lemma awn pungent; 0.5–1 mm long overall. Palea 2 -veined. Palea apex obtuse. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 2–3.

FRUIT Caryopsis with tardily free pericarp; ellipsoid; exposed between gaping lemma and palea at maturity; apex umbonate.

DISTRIBUTION North America: north-central USA, northeast USA, south-central USA, and southeast USA.

NOTES Diarrheneae. Gould.

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