Plants 2013 - Crested Coral-root

I had to wait five years to get a digital photo of a Crested Coral-root Orchid, Hexalectris spicata, at Blue Jay Barrens.  Its last appearance was in 2008 and I was able to capture the image in print and slide form.  In 2009 I was prowling the woods with my newly purchased digital camera, hoping to get some good shots of the Crested Coral-root, a plant listed as potentially threatened in Ohio.  Unfortunately, this particular orchid species often skips blooming for a year or two and my photographic attempts proved futile.  I was certainly concerned at its failure to appear for a half decade.

 

Crested Coral-root is a south-western species that has just barely extended its range into southern Ohio.  As is often the case with plants growing at the extreme limits of their range, weather conditions have a significant impact on their growth habits.  Sight of a single flower stalk on August 2, 2013 marked my first viewing of this orchid since its flowers faded back in 2008 and was the first of many found that day.

 

The actual body of the plant is found below ground and it is only the flower stalks that are exposed.  This is a plant lacking in chlorophyll, meaning no green coloration and the inability to perform photosynthesis, the means by which energy from the sun is used to convert carbon dioxide and water into carbohydrates and oxygen.  Because the plant does not require sunlight, Hexalectris can thrive in the shadiest of locations.

 

The Crested Coral-root orchids at Blue Jay Barrens grow on dry ridge tops exhibiting shallow soil over limestone bedrock.  Most of the plants are in close proximity to mature Chinquapin Oaks, Quercus muehlenbergii, like the one shown here with a lichen covered trunk.  Even though they can’t produce their own, carbohydrates are still necessary for the growth and survival of the plant.  To get what is needed, the orchid steals from other plants.

 

It’s possible that Chinquapin Oaks are a major supplier of carbohydrates to the Crested Coral-root Orchids.  The green oak leaves work through the day producing carbohydrates.  That captured energy is then moved to the tree roots for storage.

 

The act of transferring energy from tree to orchid is accomplished through filaments of mycorrhizal fungi that link the two plants.  Mycorrhizal fungi have associations with many plants and generally trade nutrients extracted from the soil for sugars produced by the plants.  Crested Coral-root Orchids have evolved to take all of their needs from their associated fungi.  It’s unclear whether or not the orchid actually gives anything back to the fungus.

 

It’s not hard to understand why these special orchids are a rarity.  First of all, just like any other plant, their seeds must fall in a location suitable for germination and development.  Secondly, the proper species of mycorrhizal fungus needs to be present and able to grow on that site.  Finally, there needs to be a compatible plant available to transfer sugars to the fungi.  Weather or other environmental factors can work on any one of the three components of this partnership with the end result being a lack of flower production on the part of the orchid.

 

Other than protecting the site from disturbance, I don’t know that there is anything I can do to improve the chances of the orchid’s survival.  I just enjoy the blooms when they appear and hope there’s not another five year absence.