This wild poinsettia is a North American cousin of the Christmas poinsettia.
Identified from the U.S. Department of Agriculture plants database, this Euphorbia heterophylla was photographed by the late Claude W. Rankin in Cumberland County, North Carolina.
It thrives in the wild from Virginia south to the tip of Florida, west along the Gulf Coast and finally including the entire state of California.
It typically blooms from June through September in the wild. It is said to be frequently cultivated.
This variant is sometimes also called painted leaf, fiddler's spurge, Mexican fireplant and annual poinsettia.
"Painted leaf" refers to the fact that there are there are other, similar spurges which have no red on their leaves. "fiddler's spurge" alludes to the fiddle-shaped leaves, which are typically two to five inches long. "Mexican fireplant" alludes to the native land of its better-known cousin, the Christmas poinsettia (euphorbia pulcherrim).
Another variant is widely called fire on the mountain. A big bed of them on the mountainside give just that impression.
Like the Christmas poinsettia (euphorbia pulcherrima), our wild poinsettia is widely characterized as an invasive or noxious weed.
The Christmas poinsettia is named for Joel Roberts Poinsett, the first U.S. ambassador to Mexico. He discovered euphorbia pulcherrima and introduced it into the United States, apparently in the early 1800's
University of Illinois Extension Poinsettia Pages
US Department of Agriculture Plant Index
US Department of Agriculture directory of invasive or noxious weeds
North Carolina State Univeristy's poisonous plants site.