This easily overlooked southeastern species has a somewhat fragmented range, and plants are usually associated with natural acidic wetlands of high quality. In addition to the few scattered Ky. records (including several old colls. of C.W. Short from JEFF), gigantea was recently found in se. Ohio (R. Gardner, pers. comm.), and it should be searched for further within the upper Ohio Valley. It is similar to louisianica in overall growth form, with long rhizomes potentially forming large patches, but it tends to occur on less fertile soils (generally non-alluvial) in thinner woods and edges. Species of section Lupulinae (gigantea, louisianica, lupulina, lupuliformis, grayi, intumescens) are often confused with those of section Vescicariae (lurida and allies). In general, section Lupulina differs as follows (FNA 23): mature achenes smaller than perigynium body (versus almost as large); perigynia ascending to spreading (versus ascending, spreading or reflexed), the bodies ca. 10-20 mm long (versus 2-12 mm), ovate (versus narrowly elliptic to ovate), 15-20-veined (versus 0-25-veined), the apex conspicuously bidentate (versus emarginate to bidentate), the teeth up to ca. 1 mm (versus 2 mm); lateral spikes pistillate or the distal 1(-5) florets androgynous or staminate (versus completely pistillate). There are no consistent vegetative differences.