Tea, coffee, and cacao are popular beverages consumed all over the world. They
are all cultivated exclusively in tropical and subtropical climates. Tea, coffee, and
cacao originate from three different continents. The tea plant is an evergreen of the
Camellia family that is native to China, Tibet, and northern India; coffee originates
from the subtropical forest ecosystems of the Ethiopian highlands, and cacao is native
to Central America where it was first domesticated by the Aztecs. Tea, coffee, and
cacao have in common relatively high concentrations of alkaloids that are stimulatory
for humans. Two structurally related compounds, theobromine and caffeine, are
especially important. Theobromine is a bitter alkaloid from the cacao plant and is also
present in the leaves of the tea plant.