Shield pennywort represents but one of about a hundred different species that belong to the Genus Hydrocotyle, a.k.a the ‘water pennyworts.’ Though often found listed as members of the Apiaceae Family, the Hydrocotyle group is now included in the ‘Ivy Family’ (Araliaceae). The genus as whole enjoys a worldwide distribution; however, the Facultative Wet H. verticillata is native to the Americas where can be found occupying floodplains, swamps, ditches, and just about anywhere with moist soils.
A perennial herb, shield pennywort is often found growing in dense mats or even rafting on open water. The rounded leaves (orbicular) leaves can grow up to 6cm in diameter and are crenate at the margin. The five-petaled flowers of Hydrocotyle verticillata are white-to-green in color and cluster together in umbels.
The above photos were taken a couple of weeks back near Panama City, Florida.
CHANDLER, G., & PLUNKETT, G. (2004). Evolution in Apiales: nuclear and chloroplast markers together in (almost) perfect harmony Botanical Journal of the Linnean Society, 144 (2), 123-147 DOI: 10.1111/j.1095-8339.2003.00247.x