Coefficient of Conservatism:
Coefficient of Wetness:
Cedar swamps and other moist forests; peatlands, especially fens, and springy places; interdunal hollows and borders of shore thickets. Very local in the southern part of Michigan.
This is our earliest-blooming species, usually at its peak by the first week of July. In the Lake Superior area, and elsewhere when near cool shores (as on islands), it may bloom later and if such plants are the rare white-flowered form they are rather easily mistaken for P. americana (which blooms still later in the same sites).
The calyx lobes in this species, while quite variable in shape, are usually more noticeably (though minutely) erose- or papillose-margined than in our other species.