Tuesday, July 19, 2011

Broad-Leaved Helleborine

There are some weeds growing in the dark woods along the trails and wood-roads.
I'm glad I decided to examine these weeds more closely because they turned out to be broad-leaved helleborine which are orchids and very interesting ones at that.
Broad-leaved Helleborine, Epipactis helleborine
The first thing I do when I see an orchid is figure out its pollination mechanism.
The broad-leaved helleborine's pollinia are designed to adhere to the head of the wasp when the wasp touches the column in the process of getting nectar from the small flower.
Pictured below is a pollinium that stuck to my finger nail as I tried to mimic a wasp visiting the orchid.
Ever see any yellowjackets wearing funny yellow hats?

Well, sticking a pollinium to a wasp's head isn't all that novel is it?   How do you keep it there until the wasp gets to the next flower?   Wouldn't the wasp just clean it off?
   Maybe that is why the broad-leaved helleborine's nectar contains alcohol and narcotics, like morphine.  A "wasted" wasp might be less likely to clean up.  If you think that it is nasty of the orchid to spike its nectar, just wait till you hear how the orchid gets the wasps to come to the flower in the first place.
   The broad-leaved helleborine uses green-leaf volatiles to attract prey-hunting wasps, like yellowjackets.  Green-leaf volatiles (GLVs) are chemical signals given off by leaves when they are under attack by herbivores. Predatory and parasitic insects use these signals to home in on their leaf-munching prey. The broad-leaved helleborine deceitfully uses those green-leaf volatiles to recruit yellowjackets to do its pollination by wearing pollinia "hats".

So, this orchid cries "wolf". 
   The broad-leaved helleborine yells, "Help! The critters are eating me".  Then the predators swoop in for the expected kill only to find spiked nectar. 
   I have this picture in my mind of a disoriented and sluggish yellowjacket wearing a funny yellow hat and buzzing (in a slurred sort of way) "all my rowdy friends are comin' over tonight"....

Watching for weeds is worthwhile.

3 comments:

  1. Very entertaining post, here Dana. Love it.

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  2. I knew you wouldn't disappoint me Dana ! What a fascinating plant.

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  3. Anonymous7/22/2011

    Talk about tricky! Thanks for letting us in on the secrets of this rather diabolical orchid! Simply amazing.

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