There are Osage orange trees growing alongside the bike trail near my home.
The Osage orange tree is native to North America. It produces a very hard wood that was used by the Osage Indians to make bows. The wood is also resistant to rot, which makes it good for fences and other outdoor structures.
In the fall the tree produces a fruit that’s about the size of your fist and the yellow-green color of a hi-viz safety vest. The fruit is wrinkled and bumpy, which has given it the popular name of “monkey brains.”
The flesh of the fruit is bitter and inedible. Inside the fruit is a milky white sap that irritates the skin. The seeds are edible and are supposed to taste like popcorn. Occasionally you’ll see a squirrel or deer chewing through the flesh of the fruit to get at the seeds, but the fruit mostly just rots where it falls from the tree. There isn’t any woodland critter that eats it.
It’s a puzzling evolutionary development, since the whole point of producing fruit is to have animals eat the fruit and disperse the seeds in their poop. Why would the Osage orange tree evolve fruit that nobody wants to eat?
The best guess is that the fruit was eaten by an animal that is now extinct, most likely the giant ground sloth or maybe the mastodon. Nobody told the tree that times had changed and it needed to up its fruit game, so it goes on as it always has.
You often hear the phrase “evolve or die,” so this would seem to be an evolutionary dead end for the Osage orange tree. But in a way you have to admire its determination. It spent a very long time developing the ideal fruit for its target audience and it’s happy with the results, thank you very much.