Bromus is a large genus of the grass family (Poaceae). Estimates in the scientific literature of the number of species have ranged from 100 to 400, but plant taxonomists currently recognize around 160–170 species. They are commonly known as bromes, brome grasses, cheat grasses or chess grasses.
Bromus is part of the cool-season grass lineage (subfamily Pooideae), which includes about 3300 species. Within Pooideae, Bromus is classified in tribe Bromeae (it is the only genus in the tribe). Bromus is closely related to the wheat-grass lineage (tribe Triticeae) that includes such economically important genera as Triticum (wheat), Hordeum (barley) and Secale (rye).
The generic name Bromus is derived from the Latinbromos, a borrowed word from the Ancient Greekβρομός. βρομός and bromos mean oats, but βρομός seems to have referred specifically to Avena sativa (Hp.Vict.2.43, Dsc.2.94, Polem.Hist.88) and Avena barbata (Thphr.HP8.9.2, Ps.-Dsc.4.137). The generic name Avena is another Latin word for oats or wild oats.
Bromus species occur in many habitats in temperate regions of the world, including America, Eurasia, Australia, and Africa. There are considerable morphological differences between some species, while the morphological differences between others (usually those species that are closely related) are subtle and difficult to distinguish. As such, the taxonomy of the genus is complicated.
Bromus is distinguished from other grass genera by a combination of several morphological characteristics, including leaf sheaths that are closed (connate) for most of their length, awns that are usually inserted subapically, and hairy appendages on the ovary. The leaf blades and sheaths, which comprise the leaves can be hairless, sparsely hairy or hairy. The inflorescence is a dense or open panicle, usually drooping or nodding, sometimes spreading (as in Japanese brome, B. japonicus).
Bromus species are generally considered to have little economic value to humans, at least in present times. The Tarahumara Indians in northern Mexico use the grains of some native Bromus species to aid fermentation in making one of their cultural beverages. As names like poverty brome (B. sterilis) and ripgut brome (B. diandrus) attest, some species are not very useful as fodder because their leaves sclerotize quickly and may even be harmful to livestock due to the high silica content. Others, such as meadow brome (Bromus riparius), native to parts of Russia, are planted as forage in the Great Plains of North America. Brome grasses are not usually grown as ornamental plants due to most species' nondescript appearance. Some are useful to prevent erosion but such use must be cautiously controlled as most Bromus have the ability to spread, becoming invasive weeds. Cheatgrass (Bromus tectorum) is a particularly troublesome weed across much of western North America (from southern British Columbia to California.)
Taxonomists have generated various classification schemes to reflect the morphological variation that is seen in Bromus. In North America, five morphologically similar groups of species, called sections, are generally recognized: Bromus, Genea, Ceratochloa, Neobromus, and Bromopsis. Sections Bromus and Genea are native to the Old World (Eurasia), but many species are introduced into North America. Sections Bromopsis, Neobromus, and Ceratochloa have several native species in North America.
Annuals or perennials. Leaves: ligule membranous. Infl usually an open panicle. Spikelets 2-many-flowered, all alike, laterally flattened; glumes unequal, persistent, keeled; lower 1-7-nerved; upper 3-9-nerved; lemmas with 2-dentate apex, awned or mucronate from the sinus.
Foodplant / miner solitary larva of Agromyza rondensis mines leaf of Bromus
Foodplant / saprobe apothecium of Albotricha albotestacea is saprobic on dead stem of Bromus Remarks: season: 2-8
Foodplant / saprobe colony of Arthrinium dematiaceous anamorph of Arthrinium phaeospermum is saprobic on dead stem of Bromus Remarks: season: esp. 7-8
Foodplant / parasite cleistothecium of Blumeria graminis parasitises live sheath of Bromus Remarks: season: 7-10
Foodplant / internal feeder larva of Cephus pygmeus feeds within stem of Bromus
Plant / resting place / within puparium of Cerodontha pygmaea may be found in leaf-mine of Bromus Other: major host/prey
Foodplant / parasite Sphacelia anamorph of Claviceps purpurea parasitises inflorescence of Bromus Remarks: season: 7
In Great Britain and/or Ireland: Foodplant / feeds on pycnidium of Ascochyta coelomycetous anamorph of Didymella phleina feeds on Bromus
Plant / resting place / on puparium of Liriomyza flaveola may be found on leaf of Bromus Other: major host/prey
Foodplant / spot causer crowded, arranged in rows or scattered, immersed, minute, fuscous pycnidium of Septoria coelomycetous anamorph of Mycosphaerella graminicola causes spots on live leaf of Bromus Remarks: season: summer
Foodplant / saprobe immersed pycnidial anamorph of Ophiosphaerella herpotricha is saprobic on stem internode (basal) of Bromus Remarks: season: 3-7 Other: minor host/prey
Foodplant / saprobe superficial conidioma of Dinemasporium coelomycetous anamorph of Phomatospora dinemasporium is saprobic on dead sheath of Bromus Remarks: season: 1-12
Foodplant / spot causer immersed, crowded or in rows pycnidium of Pseudoseptoria coelomycetous anamorph of Pseudoseptoria donacis causes spots on sheath of Bromus Remarks: season: 5-7
Foodplant / spot causer linear, long covered by epidermis telium of Puccinia striiformis var. striiformis causes spots on live inflorescence of Bromus
Foodplant / spot causer Drechslera dematiaceous anamorph of Pyrenophora bromi causes spots on live leaf of Bromus
Foodplant / saprobe scattered or in small groups, immersed pseudothecium of Pyrenophora tritici-repentis is saprobic on dead sheath of Bromus
Foodplant / spot causer immersed stromatic of Rhynchosporium coelomycetous anamorph of Rhynchosporium secalis causes spots on live sheath of Bromus
Foodplant / spot causer amphigenous, numerous, black pycnidium of Septoria coelomycetous anamorph of Septoria bromi causes spots on fading leaf of Bromus Remarks: season: 6-9
Foodplant / pathogen immersed stroma of Pseudocercosporella dematiaceous anamorph of Tapesia yallundae infects and damages live stem of Bromus
Foodplant / parasite sorus of Ustilago bullata parasitises live spikelet of Bromus
Barcode of Life Data Systems (BOLD) Stats Specimen Records:361 Specimens with Sequences:821 Specimens with Barcodes:432 Species:79 Species With Barcodes:75 Public Records:230 Public Species:65 Public BINs:0