The Collaborative International Dictionary
Jeffersonia \Jef`fer*so"ni*a\, n. [NL. Named after Thomas Jefferson.] (Bot.) An American herb with a pretty, white, solitary blossom, and deeply two-cleft leaves ( Jeffersonia diphylla); twinleaf.
Wiktionary
n. Any of several herbs of the genus (taxlink Jeffersonia genus noshow=1).
Wikipedia
Jeffersonia which is also known as twinleaf or rheumatism root, is a small genus of herbaceous perennial plants in the family Berberidaceae. They are uncommon spring wildflowers, which grow in limestone soils of rich deciduous forests. Jeffersonia was named for United States President Thomas Jefferson, by his contemporary Benjamin Smith Barton. This genus was formerly grouped in genus Podophyllum. Twinleaf is protected by state laws as a threatened or endangered plant in Georgia, Iowa, New York, and New Jersey.