Horse apples are produced by the Maclura Promifara tree and are also called Hedge Apples, Green Brains, Monkey Balls or Mock Oranges. This unusual plant is found throughout the United States, but is most common in Texas and Oklahoma. It will actually grow as either a shrub or a tree. The largest Horse Apple tree is in Virginia near the home of Patrick Henry. This interesting plant has a long history in the United States and is still in common use today.
Only the female tree produces the fruit of this unusual plant. These trees grow well in direct sun and can be grown from either a seed or cutting from an adult tree. The fruit has a green color and bumpy exterior and grows to about five inches in diameter. When cut open the fruit secretes a milky juice that is highly acidic. Care should be taken when pruning as the tree has long thorns on the branches. These trees will also spread without being cultivated and a female tree will be very messy as it produces fruit annually. The wood is extremely dense and is very useful for outdoor building as it resists weathering and pests. This resistance to pests has led to another use for the fruit.
Horse apples do secrete a substance that seems to repel spiders and other insects. Many people today place the whole fruit in their basements and other areas where insects may enter. Horses and cows can eat the horse apple but may choke if they don’t chew them completely. Horse apples are a favorite food of squirrels. Humans can eat the nuts, though they are difficult to harvest.
The wood can be used for fence posts, as it is extremely resistance to weathering and insect damage. The roots can be used to make a bright yellow dye and the bark can be used to make tanning for leather making. This versatile tree has an important place in American History and continues to be used today.