Poa matris-occidentalis

HABIT Perennial; caespitose; clumped loosely. Rhizomes elongated. Basal innovations extravaginal, or intravaginal. Culms erect; 45–80 cm long; 2–4 -noded. Culm-internodes terete (weakly); smooth; distally glabrous. Lateral branches lacking. Leaf-sheaths tubular for much of their length; with 0.66–0.8 of their length closed; 3–14 cm long; scaberulous; glabrous on surface, or puberulous. Leaf-sheath oral hairs lacking, or ciliate. Ligule an eciliate membrane; 3.5–6 mm long; obtuse, or acute. Leaf-blades 12–22 cm long; 2–6 mm wide. Leaf-blade surface scaberulous; rough abaxially. Leaf-blade margins scaberulous. Leaf-blade apex hooded.

INFLORESCENCE Inflorescence a panicle; comprising 24–85 fertile spikelets.

Panicle open; pyramidal; nodding; 10–26 cm long. Primary panicle branches (1–)2(–3) -nate; 5.5–10 cm long; bearing 3–15 fertile spikelets on each lower branch. Panicle axis with lower internodes 2.5–5.5 cm long. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with diminished florets at the apex. Spikelets ovate; laterally compressed; 4–8 mm long; 1.8–2.7 mm wide; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 1–2 mm long; obscured by lemmas; smooth. Floret callus woolly. Floret callus hairs 0.33–0.5 length of lemma.

GLUMES Glumes persistent; similar; with lower narrower than upper; shorter than spikelet. Lower glume lanceolate, or ovate; 3–5 mm long; 0.8–0.9 length of upper glume; membranous; much thinner on margins; 1-keeled; 3 -veined. Lower glume primary vein scabrous. Lower glume lateral veins obscure. Lower glume surface asperulous; rough on veins. Lower glume apex acute, or acuminate. Upper glume ovate, or obovate; 3.7–5.6 mm long; 0.8–0.9 length of adjacent fertile lemma; membranous; with hyaline margins; 1-keeled; 3 -veined. Upper glume primary vein scabrous. Upper glume surface asperulous; rough on veins. Upper glume apex acute, or acuminate.

FLORETS Fertile lemma ovate; elliptic in profile; 4.6–6.3 mm long; membranous; much thinner on margins; keeled; 5 -veined. Lemma midvein scabrous. Lemma lateral veins distinct. Lemma surface asperulous to scabrous; pubescent; hairy on veins. Lemma margins eciliate, or pubescent; hairy below. Lemma apex obtuse, or acute. Palea 4.4–6 mm long; 3 -veined. Palea keels approximate; ciliolate; adorned above. Palea surface asperulous. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 2–2.2 mm long; yellow. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp; fusiform; 2.6–2.9 mm long; light brown. Hilum punctiform.

DISTRIBUTION North America: Mexico.

NOTES Poeae. Peterson et al 2007.

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