This is a relatively uniform diploid species (2n = 24) that is widely scattered in eastern North America, usually in thin swampy forests and marshy transitions to open water. It can also disperse into small pond margins. Although largely western within Ky., discoidea may be expected in suitable habitat anywhere in the state. It is similar to frondosa and vulgata, but less robust in general. It differs as follows (FNA 21, W): calyculus bractlets 3-5 (versus 5-21), seldom ciliate (versus usually so); disc florets usually 10-20 (versus 20-150); cypselae 3-6 mm long (versus 5-12 mm).