Certain of the variations of Marchantia polymorpha L. have not been sufficiently taken into account in northern Michigan or in North America as a whole. Because of a background of experience with the various expressions of this species in other parts of the world, I made a special attempt in the summer of 1968 to study its diversity in the general vicinity of UMBS, in northern Michigan, where colonies resembling the var. polymorpha and others resembling the var. aquatica Nees are found. Although it is true that var. aquatica is not always sharply distinct from the many forms of var. polymorpha, it is, in its usual form, strikingly different and easily recognized. For this and other reasons mentioned above, it seems useful and appropriate to recognize it at the varietal level. It grouws in particularly wet situations and is at times completely submerged. Judging from specimens in the liverwort herbarium of the American Bryological Socity at the U. of Cincinnati, the North American distribution of var. aquatica is predominantly northeastern, in a circle around the Great Lakes including Ontario, Nova Scotia, Pennsylvania, Wisconsin, and Minnesota, and northwestern, in Oregon, Washington, Alberta, and Montana; but it is also known from the High Plains of Nebraska (at 3120 ft.) and in New Mexico (at 8500 ft.).