Bromus squarrosus, the rough brome, is a brome grass native to Russia and Europe. The specific epithet squarrosus is Latin, meaning "with spreading tips". The grass has a diploid number of 14.
Bromus squarrosus is an annual grass, with culms growing NaNcm (-2,147,483,648inches) high. The culms are hollow and bear four to five leaves with sheaths shorter than the blades. The leaf sheaths are pubescent and the leaf blades are typically pubescent but occasionally glabrous. The leaf blades are NaNcm (-2,147,483,648inches) long and NaNmm wide. The prominent ragged ligules are shaggy and NaNmm long. The unilateral and lax panicles have few spreading or ascending branches that are erect in youth tend to nod at maturity. The racemose panicles are NaNcm (-2,147,483,648inches) long and NaNcm (-2,147,483,648inches) wide, and the branches are typically longer than the spikelets. The spikelets are typically solitary, lanceolate in youth and becoming more ovate at maturity, and are NaNcm (-2,147,483,648inches) long and NaNmm broad. The densely flowered spikelets bear ten to twenty flowers each, with the base of the florets hidden at maturity. The glumes can be smooth or scabrous. The lower glumes are three to five-veined and NaNmm long, and the upper glumes are seven-veined and NaNmm long. The unequal and ovate lemmas have nine faint nerves and broad translucent margins measuring as broad as 1mm, and the lemmas do not roll inwards at maturity as other Bromus species typically would. The lemmas themselves are NaNmm long and NaNmm wide. The twisted and strongly divergent awns are NaNmm long. The small anthers are approximately 1mm long and have notches at their ends. The caryopses are just as long as the paleas, and are flat or slightly rolled inwards.[1] [2]
The long nine-ribbed palea and the oblong spikelets morphologically distinguish the species from most other Bromus species.[3]
The grass flowers in June and July.
Bromus squarrosus grows in overgrazed pastures, fields, and road verges. It prefers loamy or alluvial soils. It is native to central Russia and southern Europe, but is naturalized throughout southern Canada and the northern United States.[2] [4]