You've seen hedge balls scattered in parks and fields; these suspicious looking, wrinkly green balls are the fruit of the Osage orange. Commonly called hedge apples, the fruit of the Osage orange are mired in mystery and myth. People believe they are both poisonous and nontoxic; safe and dangerous for livestock; and effective or useless insect repellents. The truth is that there is a lot more speculation about hedge apples than formal study, but it is generally believed that hedge apples, while unpleasant dining fare, are not poisonous to humans or livestock.
Hedge Apples and Humans
The American Association of Poison Control Centers list hedge apples as nontoxic. For more straightforward fruits, this would be the end of the debate. However, hedge apples contain both sticky and irritating substances that can result in dermatitis. To further complicate matters, the isoflavones in the fruit have a phenolic character, similar to white willow, the precursor to aspirin. Phenolic compounds can cause severe stomach irritation, which might lead a person to believe he has eaten a poisonous fruit.
In 1804, William Dunbar and George Hunter were given the somewhat formidable task of exploring the Louisiana Purchase territory as scientists. They spent considerable time among the Osage tribes (Hunter spent most of his remaining years living among them). Hunter recorded lists of edible fruits, among which the Osage orange fruit appeared.
Hedge Apples and Livestock
Before the invention of barbed wire, livestock on the American frontier were kept in pens surrounded by Osage orange hedges. The trees presumably dropped their fruit, but no mention of its toxicity in livestock appears in folklore. After barbed wire replaced hedges, rumors began to circulate that hedge apples were highly toxic to livestock, especially sheep. Several feeding studies have shown hedge apples to be safe for ruminant animals to consume.
Bloat, Not Poison
It is believed that what is being confused for poisoning are actually the symptoms of animals choking on the sticky flesh of the Osage orange fruit. Cows choking on large pieces of hedge apple demonstrate excess salivation. The obstruction leads to bloat, which often results in death due to increased internal pressure. Because of the bitter flavor, however, livestock don't generally consume hedge apples unless food sources are scarce.