Bromus pacificus, the Pacific brome, is a perennial grass native to the Pacific coast of North America. Bromus pacificus has a diploid number of 28.
Bromus pacificus is often misidentified as various species of Bromus sect. Ceratochloa, including B. carinatus and B. sitchensis. B. pacificus resembles these species with its large and open panicles, but its lemmas are rounded or slightly keeled as compared to the flattened lemmas of B. sect. Ceratochloa. In addition, B. pacificus typically occurs only near the coast of British Columbia while species of B. sect. Ceratochloa are more widely distributed, including habitats in California where B. pacificus has been misidentified.
Bromus pacificus lacks rhizomes and grows NaNcm (-2,147,483,648inches) tall. The smooth culms are NaNmm wide at their base and have five to nine nodes. The brownish culms are relatively pubescent, with hairs up to 1mm long, though culms are occasionally glabrous with hairs only adjacent to nodes. The leaf sheaths remain closed for most of their length, being open for only NaNmm. Leaf sheaths are glabrous or pilose with hairs 2.1mm long, and lack auricles. The membranous and glabrous ligules are NaNmm long. Leaf blades are NaNcm (-2,147,483,648inches) long and NaNmm wide, with an adaxial surface covered with hairs up to 1.5mm long and a glabrous abaxial surface. Margins are smooth or slightly serrated. The open panicles are NaNcm (-2,147,483,648inches) long and NaNcm (-2,147,483,648inches) wide, with spreading or nodding branches. The spikelets are NaNcm (-2,147,483,648inches) long and number one to six per branch. The rachillas can sometimes be visible at maturity. Spikelets have six to eight florets. Glumes are pubescent, with hairs up to 0.6mm long. The one-nerved lower glumes are NaNmm long, and the three-nerved upper glumes are NaNmm long. The seven-nerved lemmas are NaNmm long and NaNmm wide, and are covered with appressed hairs up to 1.5mm long. Awns are NaNmm long. Paleas are typically shorter than lemmas, being NaNmm long, with dense cilia up to 0.5mm long. The dark brown anthers are NaNmm long.[1] [2]
Bromus pacificus occurs along the Pacific coast as its specific epithet indicates. It occurs from southeastern Alaska down to central Oregon; most often it occurs in the coast of British Columbia. Habitats include moist ravines, shaded forests, wet thickets, saline beaches, ditches, and road verges, from NaNm (-2,147,483,648feet) in elevation.[1] [3]