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urochloa

{{Short description|Genus of grasses}}

{{Automatic taxobox

| name = Signalgrass

| image = Urochloa mosambicensis flowerhead15 NWP - Flickr - Macleay Grass Man.jpg

| image_caption = Urochloa mosambicensis

| display_parents = 4

| taxon = Urochloa

| authority = P.Beauv.{{cite web |url=http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?12584 |title=Genus: Urochloa P. Beauv. |work=Germplasm Resources Information Network |publisher=United States Department of Agriculture |date=1999-03-09 |access-date=2014-10-08}}P.Beauv. Ess. Agrostogr.: 52 (1812)

| type_species = Urochloa panicoides

| type_species_authority = P.Beauv.

| synonyms_ref = {{cite web |title=Urochloa P.Beauv. {{!}} Plants of the World Online {{!}} Kew Science' |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30010413-2#synonyms |website=Plants of the World Online |access-date=4 October 2023 |language=en}}

| synonyms =

  • Brachiaria {{au|(Trin.) Griseb. in C.F.von Ledebour, Fl. Ross. 4: 469 (1853)}}
  • Leucophrys {{au|Rendle in W.P.Hiern, Cat. Afr. Pl. 2: 193 (1899)}}
  • Pseudobrachiaria {{au|Launert in Mitt. Bot. Staatssamml. München 8: 158 (1970)}}

}}

Urochloa, commonly known as signalgrass,[http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=134217 Flora of Pakistan][http://plants.usda.gov/java/profile?symbol=UROCH Urochloa.] USDA PLANTS.[http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=134217 Flora of China Vol. 22 Page 523 尾稃草属 wei fu cao shu Urochloa P. Beauvois, Ess. Agrostogr. 52. 1812. ][http://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:apni.taxon:414957 Atlas of Living Australia] is a genus of plants in the grass family, native to tropical and subtropical regions of Eurasia, Africa, Australia, the Americas, and various islands.[https://www.biodiversitylibrary.org/page/394131#page/136/mode/1up Palisot de Beauvois, Ambroise Marie François Joseph. 1812. Essai d'une Nouvelle Agrostographie 52-53] descriptions in Latin, commentary in French[https://www.biodiversitylibrary.org/page/394131#page/136/mode/1up Palisot de Beauvois, Ambroise Marie François Joseph. 1812. Essai d'une Nouvelle Agrostographie plate XI (11), figure I (1)] line drawings of flower parts of Urochloa panicoides[http://herbarium.usu.edu/webmanual/info2.asp?name=Urochloa&type=treatment Urochloa.] Grass Manual. Flora of North America.Watson, L. and M. J. Dallwitz. [http://delta-intkey.com/grass/www/urochloa.htm Urochloa.] The Grass Genera of the World. DELTA – DEscription Language for TAxonomy.

Several species of the genus Urochloa are cultivated as forage 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.{{cite book |last1=Kumble |first1=Vrinda |title=Brachiaria: Biology, Agronomy, and Improvement |publisher=CIAT |year=1996}}

Biology

This genus was described in 1812. It is similar to the genus Panicum, and some authors believe Panicum is ancestral to it. A phylogenetic analysis concluded that species of the former genus Brachiaria formed a monophyletic group with those of Urochloa, along with the genera Eriochloa and Melinis, and that further molecular and morphological work is needed to establish clear relationships.{{cite journal |doi=10.1016/j.ympev.2005.06.003 |title=Molecular and morphological phylogenetic analysis of Brachiaria and Urochloa (Poaceae) |year=2005 |last1=Torres González |first1=A.M. |last2=Morton |first2=C.M. |journal=Molecular Phylogenetics and Evolution |volume=37 |pages=36–44 |pmid=16039145 |issue=1|bibcode=2005MolPE..37...36T }}

Urochloa species are annual or perennial grasses, most lacking rhizomes. The inflorescence is a branching panicle, and the plant reaches about a meter in height.Watson, L. and M. J. Dallwitz. (2008). [http://www.biologie.uni-hamburg.de/b-online/delta/grass/www/brachiar.htm Brachiaria.] {{webarchive |url=https://web.archive.org/web/20130115104631/http://www.biologie.uni-hamburg.de/b-online/delta/grass/www/brachiar.htm |date=January 15, 2013 }} The Grass Genera of the World. Retrieved 7 November 2011. The plants are bisexual and the flowers are fleshy, with 3 anthers.Clayton, W. D., et al. (2002 onwards). [http://www.kew.org/data/grasses-db/www/gen00086.htm 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

File:Brachiaria3.jpg

Urochloa species can grow in many environments, from swamps to shady forest to semidesert, but generally do best in savannas and other open tropical ecosystems such as in East Africa. In Angola, Urochloa brizantha grows on termite mounds and in the ecotone 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.{{cite journal |doi=10.1017/S0266467400000407 |title=A preliminary investigation of small mammal biology in the Kora National Reserve, Kenya |year=2009 |last1=Alibhai |first1=S. K. |last2=Key |first2=G. |journal=Journal of Tropical Ecology |volume=1 |issue=4 |pages=321–7 |jstor=2559449|s2cid=86618426 }} 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.{{cite journal |last1=Rana |first1=B. D. |year=1975 |title=Breeding Biology of the Indian Ring Dove in the Rajasthan Desert |journal=The Auk |volume=92 |issue=2 |pages=322–32 |jstor=4084560 |doi=10.2307/4084560|doi-access=free }}

In North America, the native Urochloa platyphylla (broadleaf signalgrass), grows after heavy rains and then reproduces prodigiously and quickly, sometimes becoming a weed.{{cite journal |doi=10.1614/0043-1745(2003)051[0683:IOEFOB]2.0.CO;2 |year=2003 |volume=51 |pages=683–9 |title=Influence of environmental factors on broadleaf signalgrass (Brachiaria platyphylla) germination |last1=Burke |first1=Ian C. |last2=Thomas |first2=Walter E. |last3=Spears |first3=Janet F. |last4=Wilcut |first4=John W. |journal=Weed Science |issue=5 |jstor=4046547|s2cid=83551440 }}

Wide expanses of the tropics, especially the Neotropics, have been converted to pastures of Urochloa species to support livestock. In Brazil, 80 million hectares of native habitat have been planted with African grasses, mostly Urochloa.{{cite journal |doi=10.1016/j.agee.2003.12.010 |title=Nitrogen cycling in Brachiaria pastures: The key to understanding the process of pasture decline |year=2004 |last1=Boddey |first1=R.M. |last2=MacEdo |first2=R. |last3=Tarré |first3=R.M. |last4=Ferreira |first4=E. |last5=De Oliveira |first5=O.C. |last6=De p. Rezende |first6=C. |last7=Cantarutti |first7=R.B. |last8=Pereira |first8=J.M. |last9=Alves |first9=B.J.R. |last10=Urquiaga |first10=S. |journal=Agriculture, Ecosystems & Environment |volume=103 |issue=2 |pages=389–403|bibcode=2004AgEE..103..389B }}

Introduced species such as Urochloa grasses can degrade habitat and compete with native species. In Northern Australia, 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.{{cite journal |first1=Dan |last1=Sun |first2=Geoff R. |last2=Dickson |year=1996 |title=The Competition Effect of Brachiaria decumbens on the Early Growth of Direct-Seeded Trees of Alphitonia petriei in Tropical North Australia |journal=Biotropica |volume=28 |issue=2 |pages=272–6 |jstor=2389082 |doi=10.2307/2389082|bibcode=1996Biotr..28..272S }} 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.{{cite journal |last1=Nepstad |first1=D. C. |last2=Uhl |first2=C. |last3=Serrao |first3=E.A.S. |year=1991 |title=Recuperation of a degraded Amazonian landscape: Forest recovery and agricultural restoration |journal=Ambio |volume=20 |issue=6 |pages=248–55}} Native species may also utilize exotic Urochloa as a food resource, such as the rock cavy, a native rodent of the caatinga.{{cite book |editor1-last=Singh |editor1-first=R. J. |chapter=Forage Crops |title=Genetic Resources, Chromosome Engineering, and Crop Improvement |location=Florida |publisher=CRC Press |page=209}}

Cultivation

Image:Brachiaria field in colombia.jpg

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). [http://www.lrrd.org/lrrd16/12/holm16098.htm Impact of the adoption of Brachiaria grasses: Central America and Mexico.] Livestock Research for Rural Development 16, Art. #98. Central American 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,{{cite journal |first1=John T. |last1=McGregor |first2=Roy J. |last2=Smith |first3=Ronald E. |last3=Talbert |year=1988 |title=Broadleaf Signalgrass (Brachiaria platyphylla) Duration of Interference in Rice (Oryza sativa) |journal=Weed Science |volume=36 |issue=6 |pages=747–50 |doi=10.1017/S0043174500075767 |jstor=4044781|bibcode=1988WeedS..36..747M |s2cid=182717787 }} leafcutter ants, and mound-building termites.

Other insect pests include:{{cite book|last=Kalaisekar|first=A|title=Insect pests of millets: systematics, bionomics, and management|publisher=Elsevier|publication-place=London|year=2017|isbn=978-0-12-804243-4|oclc=967265246}}

Species

As of 2024, more than a hundred species have been accepted in the genus Urochloa:

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=Formerly included=

Numerous species once considered members of Urochloa but are now regarded as better suited to other genera,[http://apps.kew.org/wcsp/namedetail.do?name_id=449435 Kew World Checklist of Selected Plant Families] such as Alloteropsis, Ixophorus, Oplismenus, Panicum, and Rupichloa.

References

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External links

{{Commonscat-inline|Urochloa|Urochloa}}

{{Wikispecies-inline|Urochloa|Urochloa}}

{{Taxonbar|from=Q2978108|from2=Q2699312}}

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Category:Panicoideae

Category:Poaceae genera

Category:Grasses of Africa

Category:Grasses of Asia

Category:Grasses of Europe

Category:Grasses of North America

Category:Grasses of Oceania

Category:Grasses of South America

Category:Taxa named by Palisot de Beauvois

Category:Plants described in 1812

Category:Cereals