Poa pratensis

HABIT Perennial; caespitose. Rhizomes elongated. Culms erect, or geniculately ascending; 10–90 cm long; 2–4 -noded. Culm-internodes terete; smooth. Lateral branches lacking. Leaves mostly basal. Leaf-sheaths keeled; smooth. Ligule an eciliate membrane; 1–3 mm long; truncate. Leaf-blades 5–30 cm long; 2–4 mm wide. Leaf-blade surface smooth, or scaberulous; glabrous, or pubescent (rarely); sparsely hairy. Leaf-blade margins scaberulous. Leaf-blade apex abruptly acute; hooded.

INFLORESCENCE Inflorescence a panicle.

Panicle open, or contracted; oblong, or pyramidal, or ovate; dense, or loose; 2–20 cm long; 1–12 cm wide. Primary panicle branches ascending, or spreading; 3–5 -nate. Panicle branches flexuous; smooth, or scaberulous.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 0.2–2 mm long.

FERTILE SPIKELETS Spikelets comprising 2–5 fertile florets; with diminished florets at the apex. Spikelets oblong, or ovate; laterally compressed; 4–6 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes obscured by lemmas; smooth. Floret callus woolly.

GLUMES Glumes persistent; similar; shorter than spikelet. Lower glume ovate; 2–3.5 mm long; 0.8 length of upper glume; membranous; 1-keeled; 1(–3) -veined. Lower glume primary vein scabrous. Lower glume lateral veins absent, or obscure. Lower glume apex acute. Upper glume elliptic, or ovate; 2.5–4 mm long; 0.9–1 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume primary vein scabrous. Upper glume apex acute.

FLORETS Fertile lemma ovate; elliptic in profile; 3–4 mm long; membranous; much thinner above; much thinner on margins; keeled; 5 -veined. Lemma midvein scabrous; ciliate; hairy below. Lemma lateral veins distinct; stopping well short of apex. Lemma surface granulose; pubescent; hairy on veins. Lemma margins ciliate; hairy below. Lemma apex acute. Palea 1 length of lemma. Palea keels scabrous; adorned above. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 1.5–2 mm long.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

DISTRIBUTION Europe: northern, central, southwestern, southeastern, and eastern. Africa: north, Macaronesia, south, and middle Atlantic ocean. Asia-temperate: Siberia, Soviet far east, Soviet Middle Asia, Caucasus, western Asia, China, Mongolia, and eastern Asia. Asia-tropical: India, Malesia, and Papuasia. Australasia: Australia and New Zealand. Pacific: north-central. North America: Subarctic, western Canada, eastern Canada, northwest USA, north-central USA, northeast USA, southwest USA, south-central USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, western South America, Brazil, and southern South America. Antarctic: Subantarctic islands.

NOTES Poeae. CEH.

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