In Texas, only the evergreen juniper trees/bushes grow on south side of hills. Deciduous trees grow on north side. Have observed this in Oklahoma also. As you go further west in Texas, only cactus grows on south side of hills, and the evergreen junipers are only on north side. Basically the south side of hills supports only the vegetation that is most drought/heat resistant, while the north side supports vegetation that needs more moisture/shade.
In Texas, only the evergreen juniper trees/bushes grow on south side of hills. Deciduous trees grow on north side. Have observed this in Oklahoma also. As you go further west in Texas, only cactus grows on south side of hills, and the evergreen junipers are only on north side. Basically the south side of hills supports only the vegetation that is most drought/heat resistant, while the north side supports vegetation that needs more moisture/shade.