Hydrocotyle umbellata (and several close relatives in Florida)
(Hydrocotyle means water plate. An umbel is the type of flower cluster shown below.)
Araliaceae (Apiaceae)

Dollarweed Flowers by John Bradford

Dollarweed today…a monoculture, with floating rhizomes.
John and I worked today at Haney Creek Natural Area. A million bucks worth of Dollarweed there. Did you know it is native?
To help out today I’ve invited a lawn specialist, Dr. Hoppy Lubber, who agreed toshare 5 minutes of his precious time.