Ilex vomitoria, otherwise known as yaupon or yaupon holly, is a species of holly that is native to southeastern North America. The word yaupon was derived from the Catawban yą́pą, from yą- tree + pą leaf. Another common name, cassina, was borrowed from Timucua (despite this, it usually refers to Ilex cassine). The Latin name comes from an observation by early Europeans that the ingestion of the plant was followed by vomiting in certain ceremonies. Yes, this is what is used, along with other herbs and plants, in making the (in)famous “Black Drink”.
It is only one of two known plants endemic to North America that produce caffeine. The other (containing 80% less) is Ilex cassine, commonly known as dahoon holly. The plant was traditionally used by Native Americans to make an infusion containing caffeine. Yaupon leaves can be used to make a delicious tea.
Most of the time, though, yaupon is being used in landscaping in Texas and other areas within its native range. You often find them in big box home improvement stores, in the garden section. It is a rather hardy plant — it is hot-, cold-, and drought tolerant once established, and they can grow vigorously from seeds in all light conditions. That means it can spread very easily. And it is hard to get rid of once established — even after getting cut back all the way to base, it will sprout new growths when spring time comes around. Seriously consider how it could take over your garden/property if you ever consider growing yaupon for landscaping…