This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Annual caulescent herbs, with the erect stems often topped by a several-rayed umbel. Leaves scattered below the umbel, above it opposite or whor!ed, often petal-like and very showy, entire; stipules at the base of the petioles or leaf-blades, fugacious. Involucres cam-panulate, in rather dense cymes, pubescent without and within; lobes fimbriate. Glands 5, peltate, somewhat concave, with white or pink petal-like appendages. Capsule exserted, large, pubescent, the lobes rounded. Seeds narrowed upward, reticulated, with caruncles. [Greek, referring to the colored leaves or bracts.]
About 4 species, natives of North America, the following typical.
1814. Dichrophyllum marginatum Kl. & Garcke, Monatsb.
Akad. Ber. 1859: 249.
Annual, bright green, glabrous or pubescent. Stem rather stout, erect, 10'-3° tall, somewhat channelled, usually pilose, topped by a mostly 3-rayed umbel; leaves except the whorl subtending the umbel, scattered, ovate to obovate, 10'-3 1/2' long, entire, sessile; rays of the umbel forked; bracts large, white-margined; involucres cam-panulate, often clustered, 2" long, usually pubescent, bearing 3 glands subtended by white reni-form appendages; capsule depressed-globose, 3" in diameter, usually pubescent, the lobes rounded; seeds ovoid-globose, terete, about 2" long, dark ash-colored, reticulate-tuberculate.