Centrosema virginianum is known by the common names of spurred butterfly pea, wild blue vine, blue bell, and wild pea. C. virginianum is a member of the family Fabaceae, it is identified by its trailing and twining vine and showy flowers. C. virginianum habitats are in sunny areas within pine lands, and coastal uplands.
Description Centrosema virginianum is a perennial herbaceous vine growing or twining to a height approaching two meters. It has alternate pinnately divided leaves, 3 to 10 centimeters long. Leaflets are lanceolate or ovate, 1 to 4 cm long, Stipules are often deciduous, and mostly setaceous. There is a wide range of leaflet forms, from linear to ovate to oblong or lanceolate-oblong, acute or acuminate at the apex. Flowering occurs in the spring and summer.
Flowers of Centrosema virginianum, are highly specialized, with an inverted (resupinate) banner to accommodate pollinators (bees). The inflorescence consists of one to four bisexual flowers on an axillary peduncle; the calyx is deeply five-lobed, and the acute lobes are longer than the tube. The corolla is purplish or lavender-blue to nearly white; the fruit contains four to ten dark brown seeds. The diversity of leaflet shapes and corolla size and color can lead to confusion with C. pubescens. C. virginianum'''s roots are capable of nitrogen fixation.
DistributionCentrosema virginianum ranges more or less continuously from Uruguay and northern Argentina to the eastern United States and Bermuda in tropical and subtropical areas. It is widely distributed throughout the West Indies and has become naturalized in tropical West Africa.
EcologyCentrosema virginianum is a legume with high nitrogen-fixing potential. C. virginianum can tolerate overstory canopies that decrease light levels to about half of the ambient light level, meaning that it can grow in partial shade without significant affect to its nitrogen-fixing capability.Cathey, S. E., L. R. Boring, et al. (2010). "Assessment of N2 fixation capability of native legumes from the longleaf pine-wiregrass ecosystem." Environmental and Experimental Botany 67: 444-450.C. virginianum is capable of spreading clonally by production of rhizomes.Hiers, J. K. and R. J. Mitchell (2007). "The influence of burning and light availability on N-2-fixation of native legumes in longleaf pine woodlands." Journal of the Torrey Botanical Society 134: 398-409. Its seeds can remain viable in the soil seed bank for up to two years because of their hard seed coats.
As a legume, C. virginianum is high in protein and mineral content, making it attractive to a great variety of herbivorous animal species, including reptiles, mammals, and birds. Hainds, M. J., R. J. Mitchell, et al. (1999). "Distribution of native legumes (Leguminoseae) in frequently burned longleaf pine (Pinaceae)-wiregrass (Poaceae) ecosystems." American Journal of Botany 86: 1606-1614. C. virginianum thrives under a regular fire regime,Cushwa, C. T. (1966). The response of herbaceous vegetation to prescribed burning. Asheville, USDA Forest Service. and seasonal burning does not negatively affect its nitrogen fixing capabilities.Hendricks, J. J. and L. R. Boring (1999). "N2-fixation by native herbaceous legumes in burned pine ecosystems of the southeastern United States." Forest Ecology and Management 113: 167-177.
Its flower is highly specialized for pollination by large insects of the Hymenoptera Order,Spears, Jr. E. E. 1987. Island and mainland pollination ecology of Centrosema virginianum and Opuntia stricta. J. Ecol. 75: 351-362. requiring bees to "trip" the pollen delivery mechanism.Hiers, J. K., R. J. Mitchell, et al. (2003). "Legumes native to longleaf pine savannas exhibit capacity for high N2-fixation rates and negligible impacts due to timing of fire." New Phytologist 157: 327-338
See also Clitoria'', a vine with which Centrosema virginianum may be confused.
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