Tristachya avenacea

HABIT Perennial; caespitose. Rhizomes short. Culms erect; 90–120 cm long. Ligule a fringe of hairs. Leaf-blades 15–50 cm long; 3–6 mm wide.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; linear; 10–20 cm long. Primary panicle branches appressed; 1–3(–7) cm long.

Spikelets in threes. Fertile spikelets pedicelled; 3 in the cluster. Pedicels free; unequal; 1.5–3 mm long.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; laterally compressed; compressed slightly; 25–30 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; 2–2.5 mm long; bearded (rufously); pungent. Floret callus hairs 2.5 mm long.

GLUMES Glumes persistent; dissimilar; exceeding apex of florets. Lower glume lanceolate; 16–18 mm long; 0.66 length of spikelet; chartaceous; dark brown; without keels; 3 -veined. Lower glume surface glabrous. Lower glume apex acute. Upper glume lanceolate; 1 length of spikelet; chartaceous; without keels; 3 -veined. Upper glume surface glabrous. Upper glume apex obtuse.

FLORETS Basal sterile florets male; with palea; separately deciduous. Lemma of lower sterile floret similar to upper glume; lanceolate; 1 length of spikelet; chartaceous; 5–7 -veined; acute. Fertile lemma oblong; (8–)10–11 mm long; coriaceous; without keel. Lemma surface pilose. Lemma margins involute; interlocking with palea keels. Lemma apex lobed; 2 -fid; with lanceolate lobes; with lobes 1–1.5 mm long; awned; 1 -awned. Principal lemma awn from a sinus; geniculate; subterete below; 40–60 mm long overall; with twisted column; deciduous; abscissing from top of lemma. Palea 2 -veined. Palea keels approximate; thickened; winged; narrowly winged.

FLOWER Anthers 3.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION North America: Mexico. South America: Mesoamericana.

NOTES Arundinelleae. WDC 1992.

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