This is a widespread, circumboreal, variable polyploid species; 2n = 66 and 132. Its North American segregate, var. stipulacea (Coleman) Hara, has been combined ny some authors with typical Eurasian amphibia and the more southern segregate, coccinea (FNA 5; W). The only verified Ky. colls. of var. stipulacea are from rocky banks of Laurel Rv. below the dam in WHIT (BEREA, Abbott et al. 2001), and a recent discovery along Licking Rv. in HARR (JC). It is also locally abundant along the Ohio Rv. in Ind. adjacent to TRIM. McFarland (1942) listed this taxon but with no details. Variation within the amphibia-stipulacea-coccinea complex in North America, and its ecological correlations, remains poorly understood despite some taxonomic revision in recent decades (FNA 5). Mitchell (1976) showed experimentally that considerable genetic differences exist in response to flooding, but maintained that the variation is continuous. W has distinguished North Amerixan amphibia from coccinea as follows, based on sources to be reviewed: inflorescences 13-36 mm long (versus 25-90 mm) ; widest leaf blades 17-32 mm wide (versus 23-63 mm); principal emersed leaves with petioles 1-12 mm long (versus 5-38 mm), usually green when dried except for red-brown spots (versus usually tinged with red or brown), primary floating leaf blades cuneate to rounded or truncate (versus cordate to rounded)' rhizome 1.5-3.5 mm thick between leafless nodes (versus 2.8-6.5 mm), bearing few-branched to moderately branched roots (versus highly branched; stipules of emersed shoots often developing sheathing stipules with a foliaceous, outward-flange at the summit (versus not so), these flanges pubescent with wide-ascending to spreading hairs (versus glabrous or with appressed hairs). Plants on lower shorelines (perhaps typical stipulacea) may have distinct herbaceous divergent flanges (F); adjacent plants at upper levels along the Licking Rv. in HARR (perhaps forma simile Fern.) lack these flanges and are more robust.