Bromus diandrus

HABIT Annual; culms solitary, or caespitose. Culms erect, or geniculately ascending; 35–150 cm long; 3–6 -noded. Leaf-sheaths hispid. Ligule an eciliate membrane; 3–6 mm long; lacerate. Leaf-blades 4–25 cm long; 4–8 mm wide. Leaf-blade surface scaberulous; pilose.

INFLORESCENCE Inflorescence a panicle.

Panicle open; ovate; effuse; nodding; 10–25 cm long. Primary panicle branches drooping; 2–4 -nate; simple; 3–10 cm long; bearing 1(–2) fertile spikelets on each lower branch. Panicle branches flexuous; scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 5–8 fertile florets; with diminished florets at the apex. Spikelets cuneate; laterally compressed; (20–)45–60 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus evident; 1 mm long.

GLUMES Glumes persistent; dissimilar; shorter than spikelet; gaping. Lower glume linear; 15–35 mm long; 0.7–0.8 length of upper glume; chartaceous; 1-keeled; 1–3 -veined. Lower glume apex acuminate. Upper glume lanceolate; 20–45 mm long; 0.9 length of adjacent fertile lemma; chartaceous; 1-keeled; 3(–5) -veined. Upper glume apex acute.

FLORETS Fertile lemma lanceolate; 22–45 mm long; chartaceous; much thinner on margins; without keel; 7 -veined. Lemma surface scaberulous. Lemma apex dentate; 2 -fid; incised 0.1–0.2 of lemma length; awned; 1 -awned. Principal lemma awn subapical; 35–75 mm long overall; limb scabrous. Palea 0.8 length of lemma. Palea keels ciliolate. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 2–3; 0.8–1.5 mm long. Ovary with a fleshy appendage above style insertion; pubescent on apex.

FRUIT Caryopsis with adherent pericarp; linear; hairy at apex; apex fleshy. Hilum linear; 1 length of caryopsis.

DISTRIBUTION Europe: northern, central, southwestern, southeastern, and eastern. Africa: north, Macaronesia, east tropical, and south. Asia-temperate: Soviet far east, Caucasus, western Asia, Arabia, China, and eastern Asia. Asia-tropical: Malesia. Australasia: Australia and New Zealand. Pacific: north-central. North America: western Canada, northwest USA, southwest USA, south-central USA, southeast USA, and Mexico. South America: Mesoamericana, Caribbean, western South America, and southern South America.

NOTES Bromeae. Acedo 1996.

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