Tridens ambiguus

HABIT Perennial; caespitose. Culms erect; 60–125 cm long. Leaf-sheaths without keel, or keeled. Ligule a fringe of hairs; 0.5–1 mm long. Leaf-blades 2–5 mm wide.

INFLORESCENCE Inflorescence a panicle, or composed of racemes.

Panicle open; lanceolate; 8–20 cm long. Primary panicle branches ascending, or spreading; simple; 5–10 cm long. Panicle branches stiff.

Racemes borne along a central axis; 5–10 cm long.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 0.5–1 mm long.

FERTILE SPIKELETS Spikelets comprising 4–6 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 4–6 mm long; 4 mm wide; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma. Lower glume lanceolate; 2.7–4.2 mm long; 0.9 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute; mucronate. Upper glume lanceolate; 3–4 mm long; 1 length of adjacent fertile lemma; membranous; 1-keeled; 1 -veined. Upper glume lateral veins absent. Upper glume apex acute.

FLORETS Fertile lemma elliptic; 3–4 mm long; chartaceous; without keel; 3 -veined. Lemma midvein ciliate; hairy below. Lemma lateral veins close to margins; excurrent, or extending close to apex. Lemma margins ciliate; hairy below. Lemma apex dentate; 2 -fid; mucronate. Palea bowed outwards; 1 length of lemma. Palea keels ciliolate. Apical sterile florets resembling fertile though underdeveloped.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION North America: south-central USA and southeast USA.

NOTES Eragrostideae. Gould.

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