''Urochloa'', commonly known as signalgrass,
[''Urochloa''.](_blank)
USDA PLANTS. is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of plants in the
grass family
Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...
, native to
tropical
The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...
regions of
Eurasia
Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...
, Africa, Australia, the
Americas
The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...
, and various islands.
[''Urochloa''.](_blank)
Grass Manual. Flora of North America.[Watson, L. and M. J. Dallwitz]
The Grass Genera of the World. DELTA – DEscription Language for TAxonomy.
Several species of the genus ''Urochloa'' are cultivated as
forage
Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...
and some species of were probably first introduced unintentionally to the Americas in the colonial period, from slave ships. ''Urochloa eminii'' was introduced to Brazil in 1952. ''Urochloa'' is the most widely used tropical grass in Central and South America, with about 40 million hectares planted in Brazil alone.
Biology
This genus was described in 1812. It is similar to the genus ''
Panicum
''Panicum'' (panicgrass) is a large genus of about 250 species of Poaceae, grasses native throughout the tropical regions of the world, with a few species extending into the northern temperate zone. They are often large, Annual plant, annual or P ...
'', and some authors believe ''Panicum'' is ancestral to it.
[ A ]phylogenetic
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analysis concluded that species of the former genus ''Brachiaria'' formed a monophyletic group with those of ''Urochloa'', along with the genera '' Eriochloa'' and ''Melinis
''Melinis'' is a genus of African and Arabian plants in the Poaceae, grass family.
The generic name is derived from the Greek ''meline'' meaning "millet".
Species
23 species are currently accepted:
; formerly included
numerous species now reg ...
'', and that further molecular and morphological work is needed to establish clear relationships.
''Urochloa'' species are annual or perennial grasses, most lacking rhizome
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...
s. The inflorescence
In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...
is a branching panicle
In botany, 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 p ...
, and the plant reaches about a meter in height.[Watson, L. and M. J. Dallwitz. (2008)]
''Brachiaria''.
The Grass Genera of the World. Retrieved 7 November 2011. The plants are bisexual[ and the flowers are fleshy, with 3 ]anthers
The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filamen ...
.[Clayton, W. D., et al. (2002 onwards)]
''Brachiaria''.
GrassBase - The Online World Grass Flora. Some species have a prominent vein in the center of the leaf.[ ''Brachiaria'' are C4 species and can tolerate drier conditions and more light exposure than some other plants.][
]
Ecology and conservation
''Urochloa'' species can grow in many environments, from swamps to shady forest to semidesert, but generally do best in savanna
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...
s and other open tropical ecosystems such as in East Africa.[ In Angola, ''Urochloa brizantha'' grows on termite mounds and in the ]ecotone
An ecotone is a transitional area between two plant communities, where these meet and integrate. Examples include areas between grassland and forest, estuaries and lagoon, freshwater and sea water etc. An ecotone may be narrow or wide, and it ma ...
between grassland and woodland habitat.[Estes, R. D. and R. K. Estes. (1974). The biology and conservation of the giant sable antelope, ''Hippotragus niger variani'' Thomas, 1916. ''Proceedings of the Academy of Natural Sciences of Philadelphia'' 126, 73-104.] In the Kora National Reserve in Kenya, ''Urochloa'' species dominate the ground layer along with those of the genus ''Aristida
''Aristida'' is a very nearly Cosmopolitan distribution, cosmopolitan genus of plants in the Poaceae, grass family. ''Aristida'' is distinguished by having three Awn (Botany), awns (bristles) on each lemma (botany), lemma of each floret. The gen ...
''. In India, the native ''Urochloa'' ''ramosa'' is an important food source for the Eurasian collared dove and ''Urochloa'' species are forage for other local herbivores.
In North America, the native ''Urochloa platyphylla (''broadleaf signalgrass), grows after heavy rains and then reproduces prodigiously and quickly, sometimes becoming a weed
A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...
.
Wide expanses of the tropics, especially the Neotropics
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.
Definition
In biogeog ...
, have been converted to pastures of ''Urochloa'' species to support livestock
Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...
. In Brazil, 80 million hectares of native habitat have been planted with African grasses, mostly ''Urochloa''.
Introduced species
An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...
such as ''Urochloa'' grasses can degrade habitat and compete with native species. In Northern Australia
The unofficial geographic term Northern Australia includes those parts of Queensland and Western Australia north of latitude 26th parallel south, 26° and all of the Northern Territory. Those local government areas of Western Australia and Q ...
, the exotic ''Urochloa eminii'' competes with the native tree '' Alphitonia petriei'' by inhibiting the growth of seedlings, slowing the conversion of abandoned pastureland to natural forest. In the Paragominas area of Brazil, however, native forest outcompetes cultivated stands of ''Urochloa ''and other exotic forage grasses, and ranchers struggle to maintain pasture cover. Native species may also utilize exotic ''Urochloa ''as a food resource, such as the rock cavy, a native rodent of the caatinga
Caatinga () is a type of semi-arid tropical vegetation, and an ecoregion characterized by this vegetation in interior northeastern Brazil. The name "Caatinga" comes from the Tupi word '' ka'atinga'', meaning "white forest" or "white vegetat ...
.
Cultivation
''Urochloa ''is the single most important genus of forage grass for pastures in the tropics.[ ''Urochloa ''cultivars can grow in infertile and acidic soils.][ Brazil is the leading user and producer of ''Urochloa ''seeds in the Americas.][
Mexico has put effort into improving its trade in ''Urochloa ''cultivars, and the grass is thought to have made a positive impact on its milk and beef industries.][Holmann, F., et al. (2004)]
Impact of the adoption of ''Brachiaria'' grasses: Central America and Mexico.
''Livestock Research for Rural Development'' 16, Art. #98. Central America
Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
n countries have also increased seed sales and area planted in the grass.[ The annual growth rate of seed sales in 2009 was 32% in Mexico, 62% in Honduras, 45% in Nicaragua, 39% in Costa Rica, and 54% in Panama. The area planted with ''Urochloa ''during this period was about 6.5% of the total surface of permanent grasses in Mexico, 12.5% in Honduras, 1% in Nicaragua, 18.7% in Costa Rica, and 0.1% in Panama.][
Agricultural pests of ''Urochloa ''include spittlebugs,] leafcutter ant
Leafcutter ants are fungus-growing ants that share the behaviour of cutting leaves which they carry back to their nests to farm fungus. Next to humans, leafcutter ants form some of the largest and most complex animal societies on Earth. In a few ...
s, and mound-building termites
Mound-building termites are a group of termite species that live in mounds which are made of a combination of soil, termite saliva and dung. These termites live in Africa, Australia and South America. The mounds sometimes have a diameter of ...
.[
Other insect pests include:]
*shoot flies '' Atherigona oryzae'', '' Atherigona pulla'', and '' Atherigona punctata''
*caseworm '' Paraponyx stagnalis''
*red hairy caterpillars '' Amsacta albistriga'' and '' Amsacta moorei''
Species
As of 2024, more than a hundred species have been accepted in the genus ''Urochloa'':
*'' Urochloa adspersa''
*'' Urochloa advena''
*'' Urochloa albicoma''
*'' Urochloa ambigens''
*'' Urochloa argentea''
*'' Urochloa arida''
*'' Urochloa arizonica''
*'' Urochloa arrecta''
*'' Urochloa atrisola''
*'' Urochloa bovonei''
*'' Urochloa brachyura'' - eastern and southern Africa
*'' Urochloa breviglumis''
*'' Urochloa brevispicata''
*'' Urochloa brizantha'' - tropical and southern Africa
*'' Urochloa burmanica''
*'' Urochloa caboverdiana''
*'' Urochloa chusqueoides''
*'' Urochloa ciliatissima''
*'' Urochloa clavipila''
*'' Urochloa comata''
*'' Urochloa comorense''
*'' Urochloa deflexa''
*'' Urochloa dictyoneura''
*'' Urochloa distachyoides''
*'' Urochloa distachyos''
*'' Urochloa dura''
*'' Urochloa echinolaenoides'' - Democratic Republic of the Congo, Tanzania, Malawi, Zambia
*'' Urochloa eminii''
*'' Urochloa falcifera''
*'' Urochloa foliosa''
*'' Urochloa fusca'' (browntop signalgrass) - southern USA to Argentina
*'' Urochloa fusiformis''
*'' Urochloa gilesii''
*'' Urochloa glomerata''
*'' Urochloa glumaris'' - SE Asia, Indian subcontinent
The Indian subcontinent is a physiographic region of Asia below the Himalayas which projects into the Indian Ocean between the Bay of Bengal to the east and the Arabian Sea to the west. It is now divided between Bangladesh, India, and Pakista ...
*'' Urochloa grossa''
*'' Urochloa holosericea''
*'' Urochloa humbertiana''
*'' Urochloa jaliscana''
*'' Urochloa jubata''
*'' Urochloa kurzii''
*'' Urochloa lachnantha''
*'' Urochloa lata''
*'' Urochloa leersioides''
*'' Urochloa lindiensis''
*'' Urochloa longiflora''
*'' Urochloa lorentziana''
*'' Urochloa marlothii''
*'' Urochloa megastachya''
*'' Urochloa meziana''
*'' Urochloa mollis''
*'' Urochloa multiculma''
*'' Urochloa mutica''
*'' Urochloa nana''
*'' Urochloa nigropedata''
*'' Urochloa notochthona''
*'' Urochloa oblita''
*'' Urochloa occidentalis''
*'' Urochloa oligobrachiata''
*'' Urochloa oligotricha'' - Africa
*'' Urochloa olivacea'' - western Mexico
*'' Urochloa ophryodes''
*'' Urochloa orthostachys''
*'' Urochloa ovalis''
*'' Urochloa panicoides'' (panic liverseed grass) - Africa, southern Asia
*'' Urochloa pauciflora'' - western Mexico
*'' Urochloa paucispicata''
*'' Urochloa piligera''
*'' Urochloa plantaginea''
*'' Urochloa platynota''
*'' Urochloa platyphylla''
*'' Urochloa platyrrhachis'' - Zambia, Democratic Republic of the Congo
*'' Urochloa polyphylla''
*'' Urochloa polystachya''
*'' Urochloa praetervisa''
*'' Urochloa psammophila''
*'' Urochloa pseudodichotoma''
*'' Urochloa pubigera''
*'' Urochloa ramosa''
*'' Urochloa reptans''
*'' Urochloa reticulata''
*'' Urochloa rudis'' - Somalia, Kenya, Tanzania
*'' Urochloa rugulosa''
*'' Urochloa sclerochlaena'' - Ethiopia, Kenya
*'' Urochloa semiundulata''
*'' Urochloa serrata''
*'' Urochloa serrifolia''
*'' Urochloa setigera'' - Indian subcontinent, southern China, SE. Asia
*'' Urochloa stigmatisata''
*'' Urochloa subulifolia''
*'' Urochloa tanimbarensis''
*'' Urochloa texana''
*'' Urochloa trichopodioides'' - Democratic Republic of the Congo, Tanzania, Kenya, Ethiopia
*'' Urochloa trichopus'' - Africa, Arabian Peninsula
The Arabian Peninsula (, , or , , ) or Arabia, is a peninsula in West Asia, situated north-east of Africa on the Arabian plate. At , comparable in size to India, the Arabian Peninsula is the largest peninsula in the world.
Geographically, the ...
*'' Urochloa turbinata''
*'' Urochloa umbellata''
*'' Urochloa umbratilis''
*'' Urochloa uzondoiensis''
*'' Urochloa villosa''
*'' Urochloa whiteana''
*'' Urochloa wittei''
*'' Urochloa xantholeuca''
Formerly included
Numerous species once considered members of ''Urochloa'' but are now regarded as better suited to other genera,Kew World Checklist of Selected Plant Families
/ref> such as '' Alloteropsis'', '' Ixophorus'', '' Oplismenus'', ''Panicum
''Panicum'' (panicgrass) is a large genus of about 250 species of Poaceae, grasses native throughout the tropical regions of the world, with a few species extending into the northern temperate zone. They are often large, Annual plant, annual or P ...
'', and '' Rupichloa''.
References
External links
{{Authority control
Panicoideae
Poaceae genera
Grasses of Africa
Grasses of Asia
Grasses of Europe
Grasses of North America
Grasses of Oceania
Grasses of South America
Taxa named by Palisot de Beauvois
Plants described in 1812
Cereals