Tragus (plant)
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Tragus, commonly called bur gras,[1] burr grass or carrot-seed grass, is a genus of plants in the grass family. It is native to Africa, Australia, and Eurasia with several species on islands in the Atlantic, Indian, and Pacific Oceans plus one species in Argentina.[2][3][4]
Plants are monoecious, stoloniferous, and either annual or perennial depending on the species. The genus has been introduced in subtropical and tropical areas around the world as weeds of disturbed areas. The culms (stems) are ascending or low and mat forming, glabrous, and circular in cross-section. Blades are flat or folded and linear, ligules membraneous and trichomatous. Flowers are born in narrow panicles; the primary branches are spirally arranged, each possessing 2-5 spikelets; each of these spikelets bears a single floret. Each floret has 3 stamens, the anthers of which are pale yellow. The caryopses (grains) are elliptical and golden-brown.[5][6][7]
Four species of Tragus have been introduced to North America: T. australianus, T. berteronianus, T. heptaneuron, and T. racemosus.[8] The natural chromosome count is 2n = 20 in T. berteronianus, and 2n = 40 in T. racemosus.[9] Tragus species utilize C4 photosynthesis. They prevent erosion, but make for poor grazing and in larger numbers indicate overgrazing.[10]
Species
Seven species are accepted.[11][12]
- Tragus andicola M.A.Zapater & SulekicScript error: No such module "Check for unknown parameters". – Argentina (Catamarca, Jujuy, Salta, Tucuman)
- Tragus australianus S.T.BlakeScript error: No such module "Check for unknown parameters". – Australia, New Caledonia
- Tragus berteronianus Schult.Script error: No such module "Check for unknown parameters". – Africa, Arabian Peninsula, Iran, Afghanistan, Pakistan, China; introduced in North America, West Indies, South America
- Tragus heptaneuron ClaytonScript error: No such module "Check for unknown parameters". – Somalia, Kenya, Tanzania
- Tragus koelerioides Asch.Script error: No such module "Check for unknown parameters". – Zimbabwe, Namibia, Botswana, Lesotho, South Africa
- Tragus mongolorum OhwiScript error: No such module "Check for unknown parameters". – Mongolia, China, Indian Subcontinent, Indochina, Madagascar, Mauritius, Réunion
- Tragus racemosus (L.) All.Script error: No such module "Check for unknown parameters". – Africa + Eurasia from France and Canary Islands to South Africa to Kazakhstan
- formerly included[12]
several species have been placed in other genera – Brachypodium, Bromus, Festuca, Leptothrium, Lolium, Pseudechinolaena, etc. Script error: No such module "Template wrapper".Script error: No such module "Check for unknown parameters".
References
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- ↑ Script error: No such module "template wrapper".
- ↑ Haller, Albrecht von. 1768. Historia Stirpium Indigenarum Helvetiae Inchoata 2: 203
- ↑ Tropicos, Tragus Haller
- ↑ Ausgrass2, Grasses of Australia
- ↑ Script error: No such module "citation/CS1".
- ↑ Flora of China, Vol. 22 Page 495 锋芒草属 feng mang cao shu Tragus Haller, Hist. Stirp. Helv. 2: 203. 1768.
- ↑ Altervista Flora Italiana, Lappola, European Bur Grass, Klettengras, Tragus à grappes, Carretes, Tragus Template:Webarchive includes photos and distribution maps
- ↑ Biota of North America Program 2013 county distribution maps
- ↑ Script error: No such module "citation/CS1".
- ↑ Tragus koelerioides
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Kew World Checklist of Selected Plant Families
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External links
- Plants of Hawaii Gallery: Tragus berteronianus (Non-Native)
- Flora of America: Illustration of Tragus bertonianus and T. racemosus
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