Coefficient of Conservatism:
Coefficient of Wetness:
B. S. Walters
Thickets and banks along streams, rivers, and shores; marshes and meadows; ditches; borders of swamps; often in weedy places and usually in little if any shade; the twining stems often forming great tangled masses on other plants.
Authors have differed in sorting out the variation in this species; subspecies (or varieties) seem not clear-cut, and intermediates are occasional. The great majority of our material is the native pink-flowered subsp. americana (Sims) Brummitt, with open leaf sinuses. A few pink-flowered specimens from the southern half of the Lower Peninsula have the lobes of the leaf bases overlapping and the bracts and sepals apparently in a single series; these are subsp. erratica Brummitt. Also uncommon, but occurring throughout the state, is subsp. angulata Brummitt, with white flowers and spreading, two-angled leaf lobes. The European subsp. sepium is also white-flowered, but it is not clear if any Michigan material is this introduced entity, which has smaller flowers than subsp. angulata and apparently lacks the two-angled leaf lobes.