Chaste tree berries are also known as vitex or "monk's pepper." Vitex "trees" grow from 3 to 18 feet high and produce dark purple aromatic berries about the size of peppercorns that smell and taste like fresh ground pepper.
The ancient Greeks thought vitex encouraged chastity, so leaves of the plant were strewn on couches associated with Demeter, the goddess of agriculture. As this legend was passed on, monks would carry the leaves in their pockets to assist in their vows of celibacy.