During a severe drought in 2011, JennaDee Detro noticed that many trees on the family cattle ranch in Cat Spring, Texas, withered, but a certain evergreen holly appeared vigorous. It's called a yaupon."The best we can tell is that they enjoy suffering," Detro says with a laugh. "So this kind of extreme weather in Texas — and the extreme soil conditions — are perfect for the yaupon."Detro began researching yaupon — a tree abundant in its native range, from coastal North Carolina to East Texas — and discovered that the plant contains caffeine and has a remarkable history.A thousand years...