This polyploid (2n = 12 x 8) of rich mesic woods has a largely northeastern range. In Ky. there appear to be rare hybrids of diphylla with heterophylla and perhaps laciniata; see also notes under maxima. D. diphylla differs from other Dentarias of eastern North America as follows (F, FNA 7 and esp. W): rhizome elongate and of uniform diameter, lacking definite segments, but with periodic reduced leaves forming "teeth" along it (versus with 2-3 cm long segments, each separated by a narrow and fragile connecting portion which typically is broken on herbarium specimens); stem leaflets relatively broad and large (see W for details); taste of fresh plant strong, like horseradish or wasabi (versus usually less strong, mildly mustardy). Dentarias tend to have large, variable chromosome numbers, especially laciniata (Al-Shehbaz 1988b). Their genetics are complex, with clonal spread by rhizomes often substituting for sexual reproduction. Their degree of distinction from Cardamine, and recognition of many local races or hybrids, remain controversial subjects. The analysis of Sweeney & Price (2000) indicated that the concept of a monophyletic circumboreal Dentaria (with type from Europe) was not supported. But more intensive sampling and deeper analysis is needed, given the rather weak resolution of some clades, and the likelihood of much past hybridization and polyploidy. An extended or modified "Dentaria" may remain as useful in some form, albeit paraphyletic. The more thorough analysis of Carlsen et al. (2009) indicated that some of the Eurasian Dentarias are close to the North American, but the type species of the genus (D. enneaphyllos L.) was separated at the base of another large clade.