This ranges widely over eastern states, but it is largely restricted to wet acid soils. Some records mapped here need closer examination for separation of the generally more robust species, biflorus; see notes under that name. J. longii Fern. is another southeastern species (only east of the Mississippi Rv.) that may be expected, but it has often been confused with marginatus and was combined in FNA 22 (Knapp & Naczi 2008). This species differs from both marginatus and biflorus in its relatively long, slender rhizomes and stolons; it typically has intermediate stature between marginatus and biflorus. J. longii occurs mostly in boggy acid seeps on the Coastal Plain, but also extends close to Ky. on the Cumberland Plateau in Tenn. (Ch, K). J. repens Michx. may also be expected. This differs from the marginatus group in its much larger perianth (6-10 mm long versus 2-5 mm), and its arcuate-stoloniferous, mat-forming subaquatic habit. It is widespread on the southeastern Coastal Plain and extends onto the Cumberland Plateau in Tenn.