Epilobium ciliatum is an herbaceous plant of a variety of sunny to moderately shaded sites, including disturbed sites as well as more natural wetlands. Leaves are simple and opposite with very tiny and distant teeth, and with petiole none or nearly so. Flowers are small with 4 petals notched at the tip and a long inferior ovary below, which becomes an elongate fruit, similar in appearance to fruits of some mustard family (Brassicaceae) species. At maturity the fruit splits open, releasing numerous seeds, each bearing a cluster of long white hairs at the tip. There are 6 (7) other species in this genus in Wisconsin, including E. coloratum which is similar in general appearance, but has leaves with definite (though still short) petiole and larger teeth, and with brown hairs on the seeds.