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.

Bromus pacificus

HABIT Perennial. Culms 60–150 cm long; without nodal roots, or rooting from lower nodes. Culm-nodes glabrous, or pubescent. Leaves cauline. Leaf-sheaths glabrous on surface, or pubescent. Leaf-sheath oral hairs ciliate. Ligule an eciliate membrane; 2–5 mm long; brown; pubescent on abaxial surface; erose. Leaf-blades 4–10 mm wide. Leaf-blade surface smooth, or scaberulous; rough abaxially; glabrous, or pubescent; sparsely hairy; hairy adaxially, or on both sides.

INFLORESCENCE Inflorescence a panicle.

Panicle open; ovate; 15–30 cm long; with spikelets clustered towards branch tips. Primary panicle branches spreading, or drooping.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 7–11 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; compressed strongly; 20–30 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; shorter than spikelet. Lower glume lanceolate; 6–9 mm long; 0.66–0.9 length of upper glume; membranous; without keels; 1(–3) -veined. Lower glume lateral veins absent, or obscure. Lower glume surface puberulous. Lower glume apex acuminate. Upper glume lanceolate; 9–10 mm long; 0.75 length of adjacent fertile lemma; membranous; without keels; 3(–7) -veined. Upper glume surface puberulous. Upper glume apex acuminate.

FLORETS Fertile lemma oblong; 11–14 mm long; chartaceous; without keel, or keeled; 5–7 -veined. Lemma surface pubescent; hairy all along. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn subapical; 4–11 mm long overall. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3; 3 mm long; eventually exserted, or retained within floret. Ovary with a fleshy appendage above style insertion; pubescent on apex.

FRUIT Caryopsis with adherent pericarp; hairy at apex; apex fleshy. Hilum linear.

DISTRIBUTION North America: Subarctic, western Canada, and northwest USA.

NOTES Bromeae. Fl Pac NW 1994.

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