Date de publication : Contr. U.S. Natl. Herb., 7(1): 28. 1900 [31/12/1900, fide note].

Description originale : 6. Hydrocotyle australis C. & R., sp. nov.
H. canbyi Britton & Brown, Ill. Fl. 2: 540. 1897, as to habit sketch, not as to description.
Umbels few-flowered, proliferous, with 3 to 6 verticils, sometimes slightly branched; pedicels 2 to 4 mm. long; fruit 2 mm. long, slightly broader, rounded at base.
Type locality, shore of Lake Worth, Florida; collected by Curtiss, no. 5376, in 1895; type in U. S. Nat. Herb.
Virginia (Dismal Swamp), Florida, Texas.
Specimens examined:
Virginia: Dismal Swamp, Pollard 871, May 30, June, 1896.
Florida: Chapman; near Jacksonville, Curtiss 992, 4964; shore of Lake Worth, Curtiss 5378, May 8, 1895.
Mississippi: Hon Island, Tracy 4443, June 1, 1898.
Texas: Del Rio, Nealley 244, September, 1890; river near San Antonio, Dewey, June 11, 1891; near Kerrville, Kerr County, Heller 1935, June 26-30, 1894.

Type : USA, Floride, shore of Lake Worth, 08/05/1895, fleurs, A.H. Curtiss 5378 (HT: US00126912; IT: GH00103410, GH00103411, NY00405974).
USA, Floride, Chapman (près de Jacksonville), springy places, A.H. Curtiss 4964 [North American Plant 992] (PT: KFTA0001779)
USA, Virginie, Dismal Swamp, 30/05 & 06/1896, Pollard 871 (PT: ?).
USA, Mississippi, Hon Island, 01/06/1898, Tracy 4443 (PT: ?).
USA, Texas, Del Rio, 09/1890, Nealley 244 (PT: ?).
USA, Texas, river near San Antonio, 11/06/1891, Dewey, (PT: ?).
USA, Texas, near Kerrville, Kerr County, 26-30/06/1894, Heller 1935 (PT: ?).