| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|
| Araliaceae | Hydrocotyle americana | American Water-pennywort | Bogs, marshes, seepages, cliffs and ledges where wet by seepage or spray from waterfalls, sometimes roadside ditches. | Widespread in ne. North America, south to w. NC, SC, e. and c. TN, and IN, and n. AR. | 
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| Araliaceae | Hydrocotyle bonariensis | Dune Pennywort, Sombrerillo | Beaches, dunes, and moist sandy areas. | Widespread in Mexico, South and Central America, and now occurring north in North America to the Southeastern Coastal Plain, se. VA to s. FL and TX and s. AR. This species was not included in Darby (1855), Chapman (1887), or Mohr (1901); Small (1913) gave "in waste grounds and on ballast" as habitat. This suggests the likelihood that H. bonariensis is adventive from South America, and indeed it was first named from collections from South America (the epithet 'bonariensis means 'of Buenos Aires'). | 
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| Araliaceae | Hydrocotyle bowlesioides | | Lawns. | Native of Costa Rica and Panama (naturalized in South America, se. United States, and New Zealand). See Anderson (1983) for discussion of the species' occurrence in Thomasville, Thomas Co. GA. Reported for Panhandle FL (Wunderlin & Hansen 2011). See Krings, Newton, & Liles (2017) for the first report for NC (Scotland County). | 
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| Araliaceae | Hydrocotyle ranunculoides | Swamp Water-pennywort | Stagnant to (less commonly) swiftly flowing waters of swamps pools, backwaters, blackwater streams, sometimes forming floating mats. | NY, IL, MO, and KS south to s. FL and se. TX; BC south to CA, AZ, Mexico, Central America, and South America. | 
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| Araliaceae | Hydrocotyle sibthorpioides | Lawn Water-pennywort | Lawns, pond margins, cracks between paving stones. Greatly increasing as a lawn and garden weed. | Native of Asia and Africa. | 
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| Araliaceae | Hydrocotyle umbellata | Marsh Water-pennywort | Moist areas, including maritime grasslands. | NB; near the Great Lakes in w. NY, ne. OH, s. MI, n. IN, and ne. IL; MA to s. FL, west to sc. TX, south through Mexico to Central America and South America; CA south into Mexico; West Indies. Reported as a likely introduction for s. MO (Aaron 2024). | 
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| Araliaceae | Hydrocotyle verticillata | Whorled Water-pennywort | Swamp forests, pools. | Widespread in North, Central, and South America. | 
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