GrassBase - The Online World Grass Flora


W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Poa bigelovii

HABIT Annual; caespitose; clumped loosely. Butt sheaths herbaceous. Culms erect; 10–60 cm long. Culm-internodes terete. Leaves cauline. Leaf-sheaths with 0.25–0.5 of their length closed; keeled. Ligule an eciliate membrane; 1–6 mm long; glabrous on abaxial surface, or scaberulous on abaxial surface; obtuse. Leaf-blades flat, or conduplicate; 1.5–5 mm wide. Leaf-blade midrib keeled beneath. Leaf-blade surface glabrous. Leaf-blade apex abruptly acute; hooded.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; lanceolate; continuous, or interrupted; 2–15 cm long; 0.5–1.5 cm wide. Primary panicle branches appressed; 2 -nate; naked below, or bearing spikelets almost to the base. Panicle branches scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 4–5 fertile florets; with diminished florets at the apex. Spikelets ovate; laterally compressed; 4–7 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; incurved at apex. Lower glume lanceolate; 0.9 length of upper glume; membranous; much thinner on margins; 1-keeled; 1–3 -veined. Lower glume lateral veins absent, or obscure. Lower glume apex acute. Upper glume lanceolate; membranous; with hyaline margins; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma ovate; elliptic in profile; 3–5 mm long; membranous; much thinner on margins; keeled; 5 -veined. Lemma midvein ciliate. Lemma lateral veins with distinct primaries but obscure intermediates. Lemma surface smooth, or papillose; puberulous; hairy below; hairy on veins. Lemma margins ciliate. Lemma apex obtuse, or acute. Palea 0.9 length of lemma. Palea keels scabrous; adorned above. Palea surface papillose. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 0.2–1 mm long.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

DISTRIBUTION North America: northwest USA, north-central USA, southwest USA, south-central USA, and Mexico.

NOTES Poeae. Soreng 1992.

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