The story
From a European folk belief that Judas Iscariot hanged himself on a tree of this species (the account in the Christian scriptures says he hanged himself, but gives no details).
Etymology from Wiktionary, CC BY-SA 4.0.
Judas tree
Today it means: A small deciduous tree, Cercis siliquastrum, noted for its prolific display of deep-pink flowers in spring. Full definition →