Trisetum mexicanum

HABIT Perennial; caespitose. Culms 50–90 cm long. Leaf-sheaths pilose (1–2.5 mm near collar). Ligule an eciliate membrane; 2–3 mm long; truncate. Leaf-blades involute; 20–30 cm long; 1–2 mm wide. Leaf-blade surface glabrous; hairless throughout, or except near base.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; lanceolate, or elliptic; equilateral; 15–30 cm long; 1.5–3 cm wide. Primary panicle branches ascending; 3–5 cm long. Panicle axis scaberulous; glabrous. Panicle branches stiff; scaberulous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 6–9 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1–1.7 mm long; pilose; with 1–2 mm long hairs. Floret callus pilose.

GLUMES Glumes persistent; similar; reaching apex of florets; thinner than fertile lemma; shiny; gaping. Lower glume elliptic; 6–9 mm long; 0.9–1 length of upper glume; membranous; 1-keeled; 3 -veined. Lower glume primary vein scabrous. Lower glume apex acute, or acuminate. Upper glume elliptic; 6–9 mm long; 1.2–1.4 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume primary vein scabrous. Upper glume apex acute, or acuminate.

FLORETS Fertile lemma lanceolate; 5–6.5 mm long; membranous; keeled; 5 -veined. Lemma surface pilose; hairy above. Lemma apex dentate; 2–4 -fid; with lobes 0.4–1 mm long; awned; 1 -awned. Principal lemma awn dorsal; arising 0.33 way up back of lemma; geniculate; 7–10 mm long overall; with twisted column. Palea gaping; 4–5 mm long; hyaline. Palea keels scaberulous.

FLOWER Lodicules 2; obovate; 0.5 mm long; membranous; emarginate. Anthers 3; 3.2 mm long.

DISTRIBUTION North America: Mexico.

NOTES Aveneae. Fl Nov Gal 2011.

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