Vampire 

“When an orange tree drops its fruit you have to pick it up. Otherwise, as more  oranges drop to the ground, the soil will become too acidic for the tree to  survive. In the past birds, raccoons, and deer might take up the task of sweeping  the forest floor but they don't seem to be up to the job these days. Lots of  species will do themselves in if not provided with an antagonist, a mirror twin,  a predator. The osage orange (maclura pomifera) has a thick latex flesh  surrounding it's seeds. No animal wants this bitter tasting fruit and so the fruit,  and seeds with them, rot on the ground. Some think that perhaps the giant  ground sloth, in prehistoric times, ate these fruits. Humans killed off the giant  ground sloth. So these ghosts of evolution rarely get the opportunity to spread.  Without the aid of some hungry animal the circumstances that might lead to new osage orange trees are quite ridiculous. Perhaps the fruit happens to fall  into a running stream, the rocks scoring the fruit's tough hide as it bobs along  in the current. Then with any luck the fruit becomes lodged in the mud bank of  a widening stream. Then the seeds might, just might, decide to sprout."