Butterfly Pea

centrosema virginianum

Centrosema virginianum, commonly known as the spurred butterfly pea, is a delicate and attractive perennial climbing vine native to the pine barrens, sandy coastal zones, and open woodlands of the Americas. As a member of the legume family (Fabaceae), this resilient plant is celebrated for its intricate, lavender-to-violet orchid-like flowers and its crucial ecological role as a nitrogen fixer, which naturally enriches the nutrient-poor soils in which it thrives. Beyond its visual appeal, the spurred butterfly pea provides essential ecosystem services. It acts as an invaluable nectar source for native pollinators, particularly heavy-bodied bees capable of manipulating its specialized flower petals, and serves as a vital host plant for several butterfly caterpillars. Its climbing habit allows it to weave through surrounding grasses and shrubs, adding pops of vibrant color to sunny, dry landscapes. Discover and identify species like Butterfly Pea with the Snappit app.

Habitat: Typically found in dry, sandy soils within open pine flatwoods, coastal dunes, oak scrub, and disturbed roadsides.

Appearance

This climbing or trailing vine features slender, slightly hairy stems that can reach up to 200 cm in length. Its compound leaves consist of three narrow, oval-to-lanceolate leaflets. The most distinctive feature is the inverted (resupinate) flower, measuring about 3 to 4 cm across, which is predominantly pale violet, lavender, or light blue with a white and purple-striped throat. A small spur is located on the back of the broad upper petal (the banner), and the plant eventually produces long, flat, narrow seedpods that twist open when dry.

KingdomPlantaePhylumTracheophytaClassMagnoliopsidaOrderFabalesFamilyFabaceaeGenusCentrosema

Butterfly Pea

Interesting facts

Because it hosts nitrogen-fixing bacteria, this plant serves as a natural fertilizer, restoring soil quality in degraded or sandy ecosystems.

Its flowers are resupinate, meaning they develop upside down so that the stigmas and stamens point downward, brushing pollen onto the backs of foraging bees.

The common name 'spurred butterfly pea' comes from the small, spur-like projection on the back of its large banner petal.

Special abilities

Symbiotic rhizobium bacteria housed in its root nodules convert atmospheric nitrogen into a usable plant nutrient, allowing it to flourish in sterile, sandy soils.

The flowers grow upside-down compared to typical legumes, positioning the heavy banner petal at the bottom to act as a landing platform for robust pollinators.

Upon reaching maturity, the elongated seedpods dry out and build tension, eventually splitting open rapidly and twisting to fling seeds several feet away.