Bromus is a large genus of grasses, classified in its own tribe Bromeae.[ ] They are commonly known as bromes, brome grasses, cheat grasses, or chess grasses. 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.
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).
Etymology
The generic name
Bromus is derived from the
Latin bromos, a borrowed word from the
Ancient Greek βρομός (). βρομός and bromos mean
oats, but βρομός seems to have referred specifically to
Avena sativa (
Hippocrates On Regimen in Acute Diseases 2.43, Dioscorides Medicus 2.94,
Polemo Historicus 88) and
Avena barbata (Theophrastus
Historia Plantarum 8.9.2, Pseudo-Dioscorides 4.137). The generic name comes from avēna, a native Latin word for "oats" or "wild oats".
Description
Bromus species occur in many habitats in
temperate regions of the world, including
Africa,
Americas,
Australia and
Eurasia. 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 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 Bromus japonicus, B. japonicus).
Ecology
The
of some
Lepidoptera use
Bromus as a foodplant, such as the chequered skipper (
Carterocephalus palaemon).
Uses
Bromus species are generally considered to have little economic value to humans, at least in present times.
Bromus mango was historically cultivated in Chile and Argentina by indigenous peoples, who used it both as fodder and food.
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 (
Bromus sterilis) and
Bromus diandrus (
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
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
. Cheatgrass (
Bromus tectorum) is a particularly troublesome weed across much of western North America (from southern
British Columbia to
California.)
Taxonomy and systematics
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.
Selected species
== Gallery ==