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Fall 2011

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

November 8, 2011

Osage orange: Rebound from the brink

In November, softball-size fruits of the Osage orange tree collect on the ground, waiting for large mammals to stroll by and consume them.

Giant sloths, mastodons and ancient relatives of the horse may once have fed on the sticky, bright-green globes — but once humans reached North America and wiped out those megafauna, nobody was left to disseminate the seeds.

The tree's broad range eventually shrank to a small area straddling Texas, Arkansas and Oklahoma, where Osage Indians made and traded bows from the tree's highly prized, super-hard wood.

The tree began to spread again when European colonists planted it to contain their livestock. When cut, Osage orange stumps produce vigorous, thorny sprouts that form an impenetrable hedge that is "horse high, bull strong and pig tight."*

These hedges faded after the invention of barbed wire in 1875, but the tree continued to spread in a new role as a drought-tolerant, pest-free shade tree for urban areas.

City dwellers may observe squirrels or birds picking out the seeds from Osage orange fruits, but those animals destroy the seeds in the process. Only one beast will eat the whole fruit and successfully disperse the seeds in its manure. It's a large mammal introduced to this hemisphere by Europeans: the horse.

*Jonathan Turner, 1847

Osage Orange, Maclura pomifera.

SOURCES: Arnold Arboretum, Harvard University; U.S. Forest Service