Here in CA, Cal Trans plants them as highway
dividers. They also plant some kind of bush that has berries on it, birds
eat the berries and are sometimes killed, either by collision with cars or from
becoming tipsy due to eating fermented berries. But oleander is a very
prominent highway divider. One doesn't expect horses or cattle to be
wandering down a divided highway, but it's scary to think of anyway...dying from
eating it, that is.
