Originated in ancient southwestern Europe. Its tolerance to salt and lime and its intolerance of competition from other plants restrict collards natural occurrence to limestone sea cliffs on both sides of the English Channel. Ancient Greeks grew collards along with kale, and the Romans grew several kinds of collards before the Christian era. It's thought that either the Romans or the Celts introduced the vegetable to Britain and France in the 4th century B.C. With the arrival of the African slaves to the southern U.S. colonies came the Southern style of cooking collard greens. Delicious collards recipes.