Bromus diandrus Roth.

Family: Poaceae, Tribe: Bromeae

Pertinent Synonyms & Notes (particularly those used in California; go to GRIN for other synonyms)

Bromus rigidus Roth, B. gussonei Parl.

Pertinent Common Names (particularly those used in California; go to GRIN for other common names)

great brome, ripgut brome

Primary Disseminule Type


Description (diagnostics are in brown)

Spikelets solitary, pedicelled, consisting of 4–8 fertile florets with similar-looking though diminished sterile florets at apex, cuneate, slightly laterally compressed, (20)45–60(70) mm long, disarticulating below each fertile floret at maturity.

Glumes persistent, dissimilar, shorter than spikelet, chartaceous, margins hyaline, gaping, keeled, surface smooth or scabrous. Lower glume linear, 15–35 mm long, 0.7–0.8 length of upper glume, 1–3-veined, apex acuminate. Upper glume lanceolate, 20–45 mm long, 0.9 length of adjacent fertile lemma, 3–5-veined, apex acute.

Fertile florets: rachilla persistent, hairy, callus sharply pointed, 1 mm long, bearded.

Lemma linear-lanceolate, sometimes slightly arched, 18–35(45) mm long (excluding awn), chartaceous, much thinner (hyaline) on margins, with rounded back (no keel), 7-veined, midvein ribbed, lateral veins obscure to somewhat ribbed, surface scaberulous, apex acuminate, bifid, teeth 3–7 mm long, awn subapical, 30–75 mm long, scabrous.

Palea 0.7–0.8 length of lemma (excluding lemma teeth), keels ciliolate.

Caryopsis linear, 11–14 mm long x 1–2.8 mm wide, brown, apex fleshy and hairy, hilum linear, same length as caryopsis.

Similar Species

Similar Species Comparison Chart

Risk Assessment (codes in yellow or red indicate cause for concern; assessments are current as of mid-2011; click AUQP, NZBORIC, or NZBPI for access to the most recent versions of these databases and possible assessment changes)