Naturespeak A naturalist's view of the world

October 3, 2007

Elephant Trees

Filed under: Uncategorized — wykes @ 10:52 pm

   Among the many thousands of things classified by the great Swedish naturalist Karl Linnaeus was a very prickly giant American bean plant which he called Gleditsia triacanthos -which translates into “Mr. Gleditsch’s three spine tree.”  Gottlieb Gleditsch was a botanist and director of the Berlin Botanical Gardens in the 1700’s. The decision to pin Mr. G’s name on this tree probably had nothing to do with his personality, but rather would have been an honor.  Gleditsch was one of Linnaeus friends and a defender of his ideas (one of which includes something called binomial nomenclature, the system by which all living things are now designated with a unique two part scientific name). Here’s a picture of the crusty old Mr. G his-self.

  The tree which bears Gottieb’s surname is better known around these parts as the Honey locust.  The wild tree grows throughout the East Central United States but only barely makes it into the southern tier of counties in Michigan (Monroe & extreme southern Wayne included). Chances are you have a Honey Locust along your street or in your landscaping (it probably looks like this). Labeled with tags that say Sunburst, Shademaster, and Majestic, these domestics are trademarked products of selective breeding that bear little resemblance to its wild form.  Their array of compound leaves, gilded with tiny leaflets, cast gentle sidewalk shade. When those tiny leaves fall in autumn, they don’t need to be raked (ahhhh, now we know why they are planted so often!).

  The two distinctive traits that make a Honey Locust a Honey Locust -the large flat seed pods and the formidable thorns – are the two things that have been bred out of the yard plant.  One needs to visit a wild locust to get an appreciation for the true soul of the plant (something like comparing a wolf to that lazy mutt chasing his tail in your backyard under the Sunburst Honey Locust). 

  I encountered a pack of savage Honey Locust in the woods of southern Ohio.  Here they are sizable trees. They surrounded me as the waning moon looked on (see here – note the compound leaves and pods).  Bristling with thorns (see here) and draped with an unkempt collection of dangling bean pods (they are in the bean family) they declared “We are wild and free locusts.”  These wild spirits spoke of ancient family ways long forgotten by their spineless relations.

  Tremendous branching thorns cover the trunk and lower branches.  Young thorns have only three branches, thus the “three spine” part of the scientific name.  Older spines continue to branch and grow to a foot or more in length.  In the south, these trees earned the name of Confederate Pin Trees because the war worn followers of Jeff Davis were known to use the thorns to pin their ragged uniforms together.  Beyond the cause of southern dignity, the question remains as to why such a bristly defensive array is necessary?  The answer lies in the distant past long before the rebellion when large beasts roamed these woods.

  Until about 12,000 years ago, massive Mastodons and Giant Ground Sloths fed upon the fruit of such trees.  Honey Locust pods are full of a sweet edible pulp that fills the spaces between the seeds (see here for a view of the pods and here for a peak at the sweet interior).  This is why Gottlieb’s tree is called the Honey Locust, by the way. The sweets were a deliberate ploy to tempt big herbivores to eat them and pass the indigestible seeds though their digestive system.  Once passed, the scarified seeds could germinate. The problem is that the big boys sometimes got carried away in their eating frenzy and started to strip away the bark and tear away branches.  The thorns were developed to put a stop to such nonsense. Big giant thorns were needed to penetrate thick giant hides.  “Enjoy the fare, guys, but don’t mess up the kitchen,” was the clearly broadcasted message. 

  In Africa, where there still are large plant-eating elephants and high toppers like giraffes around, many plants possess such defensive thorns for the same reason.  Our North American elephants and mega fauna became extinct long ago – leaving the Honey Locust with a useless system of defense.  The pulpy seed pods are still edible, but now have to be satisfied with passing out the hind end of domestic cows.

  Horticulturalists have simply accelerated the process and rid the tree of a useless accessory.  The spineless locust may be the plant of the future, but there is no denying its brutish Ice Age past.

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