The genus is characterised by trifoliate leaves and small yellow flowers[4] Species may beannual orperennial and morphology varies between species as well as within species in response to grazing pressure. Some species such asS. scabra grow as a low woody shrub to 1.5 m, while others such asS. humilis will grow as a herbaceous shrub but can adopt a prostrate growth form and thrive under high grazing pressure.[5]
Taxonomy of the genus remains unsettled and controversial, with various authors favouring between 25 and 42 species, with at least 40 additional synonyms.[6] The taxonomy is complicated by the existence of numerous naturaltetraploid andhybrid populations.[7] Species within the genus fall within two subgenera:Styposanthes andStylosanthes.Styposanthes possess a small rudimentary secondaryfloral axis, which is absent fromStylosanthes.[8]Stylosanthes is closely related to the peanut genusArachis.[6]
All except two species of the genus are native to the Americas.S. fruticosa has a native range that extends fromSouth Africa toEthiopia, acrossArabian Peninsula toPakistan,India andSri Lanka[9] andS. erecta is endemic to Tropical Africa, fromTanzania toSenegal.[10] The putative speciesS. sundaica, has a range that encompassesMalesia but is considered by most authors to be an adventive polypoliod variety ofS. humilis.[9] Ecological range extends from savanna and thorn scrub to tropical forest and montane forests.[6]
Species within the genus have many properties that make them valuable forage species. They are capable ofnitrogen fixation and are capable of improving soil fertility in addition to providing high protein stock feed.[12] The genus is also noted for its ability to extract phosphorus from soils where it is not available to other species.[13] Seeds are hard and long lived leading to high soil seed banks and rapid recovery following fire or heavy grazing. Seed survives passage through the gut of grazing animals and is dispersed widely in this manner allowing for rapid dispersal.[5] Many species are adapted to hot, dry climates and are drought resistant.[14]
These traits have made the genus the world’s most widely used tropical pasture legume.[14]Stylosanthes has been introduced across the tropical world as a pasture species. Its most important use has been inAustralia where over a million hectares of primarily native pasture have been oversown withStylosanthes species; primarilyS. hamata,S. scabra andS. humilis[15] This can lead to a ten-fold increase in productivity, though 2–3 fold increases are normal.[5]Stylosanthes are the most important forage legumes inSouth America[16] and the most important pasture legumes of tropicalIndia.[17]Stylosanthes are also important forage species in tropical Africa.[5]
Stylosanthes are important green manure species inWest andCentral Africa, primarilyS. guianensis andS. hamata, and species are planted and harvested for commercial leaf meal production for poultry and pig feed inChina andIndia. The genus has also been used as a nitrogen input into low input or organic cropping systems. Species are used as fallow species inPeru,Africa andAustralia. S. hamata used for intercropping with grain crops in India and Africa with yield increases up to 25%.[5]
Stylosanthes species have been used for land reclamation, soil stabilization andsoil regeneration work because of their drought resistance, ability to restore soil fertility, improve soil physical properties and provide permanent vegetation cover.[17][18][19][20]
Despite their ability to dramatically improve productivity in grazing lands,Stylosanthes can also cause problems.Stylosanthes can dominate pasture at the expense of grass which can lead to problems because the plants provides less protection fromerosion than grass.[5]Stylosanthes dominance can also lead tosoil acidification, as soil nitrate levels build up and are then leached down the soil profile.[21]Stylosanthes species are considered invasive species and environmental weeds inAustralia,Taiwan, thePacific Islands andHawaii.[6] ManyStylosanthes species are susceptible toanthracnose fungus (Colletotrichum gloeosporioides) which retards growth and seed development,[5] and this had led to numerous commercial cultivars being abandoned.
^Lavin M, Pennington RT, Klitgaard BB, Sprent JI, de Lima HC, Gasson PE (2001). "The dalbergioid legumes (Fabaceae): delimitation of a pantropical monophyletic clade".Am J Bot.88 (3):503–33.doi:10.2307/2657116.JSTOR2657116.PMID11250829.
^Sa R (萨仁); Salinas AD (2010)."笔花豆属" [61.Stylosanthes Swartz, Prodr. 7, 108. 1788.]. In Wu ZY (吴征镒); Raven PH; Hong DY (洪德元) (eds.).Flora Republicae Popularis Sinicae [Flora of China]. Vol. 10 (Fabaceae). Missouri Botanical Garden Press, St. Louis, and Science Press, Beijing. pp. 135–136.ISBN9781930723917. Retrieved12 February 2014.
^abCook B, Pengelly B, Brown S, Donnelly J, Eagles D, Franco A, Hanson J, Mullen B, Partridge I, Peters M, Schultze-Kraft R (2005)."Tropical Forages entry forStylosanthes".Tropical Forages. CSIRO Sustainable Ecosystems (CSIRO), the Department of Primary Industries and Fisheries (DPI&F Queensland), el Centro Internacional de Agricultura Tropical (CIAT), and the International Livestock Research Institute (ILRI). Retrieved12 February 2014.
^Kretschmer AE, Pitman WD (2001). "4. Germplasm Resources of Tropical Forage Legumes". In Sotomayor-Ríos A, Pitman WD (eds.).Tropical Forage PLants: Development and Use. CRC Press LLC, Boca Raton, Florida. pp. 41–58.doi:10.1201/9781420038781.ch4 (inactive 2024-11-12).ISBN978-0849323188.{{cite book}}: CS1 maint: DOI inactive as of November 2024 (link)
^Hall T, Glatzle A (2004)."Cattle production fromStylosanthes pastures"(PDF). In Chakraborty S (ed.).High-Yielding Anthracnose-ResistantStylosanthes for Agricultural Systems. Australian Centre for International Agricultural Research (ACIAR). pp. 51–64.ISBN978-1-86320-442-2.
