Euphorbia subg. Poinsettia is a subgenus of Euphorbia endemic to North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 (Mexico). It contains around 24 species, of which the best known is E. pulcherrima, the poinsettia.

This taxon was first published at genus rank under the name Poinsettia by Robert Graham

Robert Graham (botanist)

Robert Graham was a Scottish physician and botanist. He was the inaugural chair of botany at the University of Edinburgh...

 in 1836. It was demoted to a section of Euphorbia as E. sect. Poinsettia by Henri Ernest Baillon

Henri Ernest Baillon

Henri Ernest Baillon was a French botanist and physician. He was born in Calais on November 30, 1827 and died in Paris on July 19, 1895.Baillon spent his professional life as a professor of natural history, and he published numerous works on botany...

 in 1858, but promoted to subgenus rank by Homer Doliver House in 1924. Recent studies have confirmed its monophyly

Monophyly

In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...

.

Species include E. pulcherrima (Poinsettia), E. cyathophora (Summer Poinsettia), E. dentata

Euphorbia dentata

Euphorbia dentata is a species of spurge known by the common names toothed spurge and green poinsettia. It is native to parts of North and South America, and is present elsewhere on the continents. Its true native range is uncertain. It is a noxious weed in some areas...

(Green Poinsettia), E. heterophylla

Euphorbia heterophylla

Euphorbia heterophylla, also known under the common names of fireplant, painted euphorbia, desert poinsettia, wild poinsettia, fire on the mountain, paint leaf and kaliko plant, is a plant belonging to the Euphorbiaceae or spurge family.This plant has many synonyms; one of the most common is...

(Desert Poinsettia), and E. pinetorum (Everglades Poinsettia).