''Aristida'' is a very nearly

cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...

genus of plants in the

grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

. ''Aristida'' is distinguished by having three awns (bristles) on each

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), ...

of each

floret This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...

. The genus includes about 300

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

found worldwide, often in arid warm regions. This genus is among those colloquially called three-awns wiregrasses, speargrasses and needlegrasses. The name ''Aristida'' is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

" arista", meaning "awn". They are characteristic of

semiarid A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi- ...

grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...

. The

Wiregrass Region The Wiregrass region or Wiregrass country is an area of the Southern United States encompassing parts of southern Georgia, southeastern Alabama, and the Florida Panhandle. The region is named for the native ''Aristida stricta'', commonly known a ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

is named for '' A. stricta''. Other locales where this genus is an important component of the

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

include the Carolina Bays, the sandhills of

the Carolinas The Carolinas are the U.S. states of North Carolina and South Carolina, considered collectively. They are bordered by Virginia to the north, Tennessee to the west, and Georgia to the southwest. The Atlantic Ocean is to the east. Combining Nor ...

, and elsewhere, Mulga scrub in

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

, and the

xeric Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this h ...

grasslands around

Lake Turkana Lake Turkana (), formerly known as Lake Rudolf, is a lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. B ...

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

. Local increases in the abundance of wiregrasses is a good indicator of

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...

, as

livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to ani ...

avoid them.

Description

''Aristida'' stems are ascending to erect, with both basal and cauline leaves. The leaves may be flat or inrolled, and the basal leaves may be tufted. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are forme ...

s may be either

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 ...

-like or

raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...

-like, with spiky branches. The

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 ...

s of a spikelet are narrow lanceolate, usually without any awns, while the lemmas are hard, three-veined, and have the three awns near the tip. The awns may be quite long; in ''A. purpurea '' var. ''longiseta'' they may be up to 10 cm.

Species

Selected species include:

References

{{Taxonbar, from=Q311128 Poaceae genera Taxa named by Carl Linnaeus

Description

Species

See also

References