Osage oranges (Maclura pomifera, Moraceae) are interesting trees, mostly because of their large fruit. Although native to Texas, Oklahoma, and Arkansas, they have been introduced over much of the United States and southern Ontario.
The fruit are roughly the size of an orange, and can bear a citrus scent. The similarities to oranges stop there. This plant is in the mulberry family (Moraceae) while oranges are in the citrus family (Rutaceae).
These are multiple fruits much like pineapples, figs, and mulberries. Flowers grow in a dense cluster and each flower upon pollination forms its own little fruit. The density of these fruits lead them to form one solid mass like the one seen above. Although this fruit is generally unpalatable to humans, it may have been attractive to Pleistocene megafauna that could have aided in seed dispersal.