Poinsettia

The Latin generic name "Euphorbia" commemorates the Greek physician Euphorbus, who in the 1st century AD treated the ruler of Mauritania, Juba II, with the milky sap of plants from the genus Euphorbia.

An excerpt from the article 16 facts about Poinsettia
The species name "pulcherrima" was given to the plant by the German botanist Carl Ludwig Willdenow.