''Bromus rigidus'', the ripgut brome, is a grass native to Eurasia and naturalized in North America. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''rigidus'' means rigid or stiff.

Description

''Bromus rigidus'' is an annual grass growing tall. The culms, leaves, and

panicle A panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a panicle are of ...

branches are all pubescent or harsh. The erect or ascending panicle has short branches that terminate in four to nine flowered

spikelet A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other Monocots. Each spikelet has one or more florets. The spikelets are further grouped into panicles or spikes. The part of the spikelet that ...

s. The reddish spikelets are long, including the

awn AWN may stand for: * Awn Access to Justice Network in Gaza Strip, Legal Aid Network operate in Gaza Strip, Palestine * Animation World Network, an online organization for animators * Avant Window Navigator, a dock-like bar that tracks open windows ...

s measuring long. The first

glume In botany, a glume is a bract (leaf-like structure) below a spikelet in the inflorescence (flower cluster) of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and ...

has one nerve and the second has three. The lance-attenuate

lemma Lemma may refer to: Language and linguistics * Lemma (morphology), the canonical, dictionary or citation form of a word * Lemma (psycholinguistics), a mental abstraction of a word about to be uttered Science and mathematics * Lemma (botany), a ...

s are unequal, with the lower having a long tooth on each side of the awn and the upper tapering to the beak. The scabrous lemmas are strongly ciliate. The

anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

s are approximately long. The common name "ripgut brome" refers to the heavy

sclerotization Sclerotization is a biochemical process that produces the rigid shell of sclerotin that comprises an insect's chitinous exoskeleton. It is prominent in the thicker, armored parts of insects and arachnids, especially in the biting mouthparts and scle ...

of the species, creating a hazard to livestock. The seeds of the plant can penetrate the skin of livestock and the callus and awns can penetrate the mouth, eyes, and intestines of livestock. ''Bromus rigidus'' differs from the closely related ''Bromus diandrus'' in its shorter laminar hairs and more compact panicle with shorter spikelet branches. The elliptical abscission scars on rachillae and elongated lemma calluses of ''B. rigidus'' further distinguish the species from ''B. diandrus'', with the latter possessing more short and circular scars and calluses. ''B. diandrus'' is susceptible to rust such as ''Puccinia bromoides'' whereas ''B. rigidus'' is unaffected.

Habitat and distribution

''Bromus rigidus'' is common in waste places and rare near ports in the United States, occurring around areas such as

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

District of Columbia ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

and north to

Massachusetts Massachusetts (Massachusett language, Massachusett: ''Muhsachuweesut assachusett writing systems, məhswatʃəwiːsət'' English: , ), officially the Commonwealth of Massachusetts, is the most populous U.S. state, state in the New England ...

. In Europe the grass occurs in the south and west, growing in weedy or disturbed areas, road verges, and ports.

References

External links

* {{Taxonbar, from=Q12219290 rigidus Plants described in 1775 Flora of Malta