Tuesday, August 9, 2011
I was recently invited to join a small foray into a north-central Ohio forest by Cheryl Harner, who had been keeping tabs on one of the most significant - at least to a botanist - plants that occurs amongst the beech and maple.
And discover one of our most mysterious orchids, the ornithologically named three-birds orchid, Triphora trianthophora. I had only seen this species one other time, and that population was in a remarkably similar setting albeit 100 or so miles away.
Andrew Gibson, and Warren Uxley get down low to better admire the diminutive orchids. There were perhaps 100 of the plants growing in a ring around that sugar maple, Acer saccharum. Where I had seen three-birds before, they were growing in much the same way but were encircling a beech, Fagus grandifolia. Those two tree species, which together form a classic forest composition, are the two species to key in on when seeking three-birds orchid.
In many of the populations of three-birds orchid that I have some knowledge about, it seems as if the plants typically grow in a "fairy ring"; they encircle the base of a large tree as these plants were. Conventional wisdom has it that Triphora seeds are probably wind dispersed, as they are tiny and dustlike. Each fruit capsule contains hundreds if not thousands of seeds. However, I wonder about this and think someone needs to do further study on the dispersal of this strange little orchid.
Oftentimes, when one sees a plant growing in profusion in a ring around a large tree, it is probably the result of their fruit being harvested by arboreal ants. The insects collect and haul the tasty seeds to the tree, and rather than lug the whole seed up the trunk, they bite off the nutrient rich seed base and leave the seed proper on the ground at the tree's base. Over time, a profusion of plants springs up around the mother tree. I wonder if that isn't what happens with this orchid, especially as dense forests are largely sheltered from strong winds and not the sort of places that one would predict that the evolution of wind-dispersed plant fruit would occur.
Some seasons, the three-birds never do appear above ground. They live a subterranean existence as tuberoids, intimately interwoven with certain types of fungus which are required to help fuel the orchid's growth.
It was truly a treat to once again see this mysterious little denizen of the late summer forest, and ponder its mysteries.