Yaupon (Ilex vomitoria), also called Cassina (the latter shared with the Dahoon Holly), is an evergreen holly found in the southeast United States. It is a shrub or small tree reaching 5-8 m tall. The leaves are alternate, ovate to elliptical with an acute apex and crenate or finely serrated margin, 2-4.5 cm long and 1-2 cm broad, glossy dark green above, slightly paler below.
Yaupon flowers are white, with a four-lobed corolla. The fruit is a small round or red (occasionally yellow) berry 5-6 mm diameter containing four seeds.
Cultivation and uses Native Americans used the leaves and stems to brew a tea called Asi or Black Drink for male-only purification and unity rituals. The ceremony included vomiting, and Europeans incorrectly believed that it was the drink itself that caused it (hence the Latin name). The active ingredient is actually caffeine, and the vomiting was either learned or as a result of the great quantities in which they drank the beverage (Hudson, The Southeastern Indians, ISBN 0-87049-248-9).