Tuesday, August 21, 2012

Osage Orange

The drought has choked the wildflowers and muted the usual summer colors, leaving lots of gray and straw colored grass as well as yellowing of leaves.  The only color to be seen across the south field are the yellow-green balls hanging on a few distant trees.  You may have seen one close up on Saturday's blog quiz.*  These are the infamous hedge apples.

Osage orange Maclura pomifera, is a shrub or small tree, a member of the mulberry family.  Squint at the softball sized fruit and you can begin to see the resemblance to a mulberry.  This plant has an interesting history as well as a reproductive strategy which seems outdated for our modern world.

Like all other living organisms, procreation is "job one" for plants.  Seeds may be dispersed by wind or animals which eat them and pass them on.  The massive fruit of the Osage orange isn't regularly eaten by any native species aside from squirrels, although cattle and horses which arrived on this continent around 500 years ago will occasionally nibble them some. 

Osage orange native range- Wikimedia
The most interesting theory is that they were commonly eaten by the megafauna such as giant ground sloths, mammoths and mastodons prior to their extinction coincident with the arrival of humans 12,000 to 15,000 years ago.  They would have been capable of spreading their seeds in the temperate areas as the glaciers were retreating.  Like the honey locust with its large seed pods, the Osage orange comes complete with thorns capable of discouraging the browsing mouths of herbivores.**

Their home range in recent times was in Texas and a bit of Oklahoma.  Lewis and Clark sent cuttings acquired from Pierre Chouteau, a founding father of St. Louis, to President Thomas Jefferson but they failed to grow.  Osage orange had already achieved fame among many native American tribes as the best wood for making bows.  This is cited as one possible source of its early French name, bois d'arc, or "bow wood."

Osage orange is now naturalized throughout the United States.  It received its boost during the dust bowl days when 220 million trees were planted in shelter belts to reduce wind erosion.  Their spreading branches with short thorns made natural fences before barbed wire, then provided decay and termite resistant fence posts for the wire.

Dispersal by megafauna over thousands of years failed to accomplish what an invasive species of bipeds did in a hundred years.  There is a message here for future generations.
* I received a correct answer within the first hour.  Sarah Zahn recognized the closeup of a hedge apple, the fruit of the Osage orange.
** Discussed further in a previous blog.

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