The genus Jeffersonia was named by Benjamin Barton in honor of Thomas Jefferson, third president of the United States. There are only two species in the genus—Jeffersonia diphylla, commonly called twinleaf, which is native to the northeastern United States and J. dubia from eastern Asia.
Twinleaf is found in rich mesic forests in seventeen eastern states, often on slopes and usually over limestone or other calcareous rock.
This beautiful little plant is uncommon to occasionally encountered in most states, considered rare in nine states (Minnesota, Iowa, Wisconsin, Michigan, New York, New Jersey, North Carolina, Georgia, and Alabama), and is protected as a state-listed species in four states (Georgia, Iowa, New York, and New Jersey).
Twinleaf is uncommon in Illinois, but it is not currently considered rare or protected.
Twinleaf's showy white flowers appear in early spring (early to mid-April) and are present for a very short time, being blown off by the slightest breeze. They rarely last more than a single day.
The flowers appear to be pollinated by small halictid bees; however, they exhibit an apparent self-pollinating mechanism that ensures seed production without insect visitation. Two to three days after flower initiation, often with the showy petals already lost, the eight stamens all bend inward to contact the stigma. The resulting fruit matures in early to mid-June.
The fruit is an interesting pear-shaped capsule that when fully open has the appearance of a frog with a gaping mouth.
After flowering, twinleaf's namesake leaves continue to grow until they resemble a pair of small elephant ears.
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References:
Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP)].
O’Rourke George, L. 1997. Jeffersonia. In: Flora of North America north of Mexico, Volume 3. Oxford University Press, New York, NY
Smith, B.H., M.L. Ronsheim, and K.R. Swartz. 1986. Reproductive ecology of Jeffersonia diphylla (Berberidaceae). American Journal of Botany 73(10):1416–1426.