Annual bunchgrass. Stems 30–60 cm. Leaves: blades 4–8 mm wide. Inflorescence a nodding panicle 7–12 cm long. Spikelets 10–15 mm long, with 5 to 8 florets. Lemmas with a straight or down-curved awn 10–20 mm long (Lavin in
Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Rye Brome -
Bromus secalinus, exotic and undesirable
*Spikelets twisted, not purplish-tinged, and with distinct lemmas separated enough to expose the rachilla
and*Anthers 1-2 mm long
and*Lower leaf sheaths glabrous or loosely pubescent and glabrate.
Field Brome -
Bromus arvensis, exotic, undesirable, and NOT documented in Montana
*Spikelets purplish-tinged
and*Anthers 2.5-5 mm long
and*Lower leaf sheaths with soft appressed hairs.
Japanese Brome -
Bromus japonicus, exotic and undesirable
*Spikelets not purple-tinged and with close together lemmas that cover the rachilla
and*Anthers 1-1.5 mm long
and*Lower leaf sheaths are usually densely pilose.