Identifying Purple Fringed Orchids

P. grandiflora vs. P. psycodes
Purple fringed orchids are hard to mistake for any other flower, yet when faced with deciding between the lesser purple fringed orchid (Platanthera psycodes) and the greater purple fringed orchid (Platanthera grandiflora), it can be difficult to settle on an ID.

First off, if you find a purple fringed orchid, it is more likely to be P. psycodes, since it is more common than P. grandiflora. Flowers on P. psycodes are often smaller and wither on the bottom before the buds on top open, whereas on P. grandiflora the flowers on the bottom typically remain open longer. The most reliable characteristics are the spur opening (round on P. grandiflora) and the rostellum lobes (with “tails” on P. grandiflora).

Before using any of these tips, remember that my drawings aren't perfect and that no individual orchid is exactly alike. Also take care not to be thrown off by color variations, lack of fringing, etc

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Posted on 08 October, 2017 01:43 by arethusa arethusa


Nice drawing & description! I need something like this for Spiranthes...

Posted by eraskin over 6 years ago

Which species? I may be able to make one.

Posted by arethusa over 6 years ago

Pretty much all of the ones in western NC/the southern Appalachians, although I might gain some clarity if I went back to the key & puzzled over it some more.

Posted by eraskin over 6 years ago

I suppose I could.

Posted by arethusa over 6 years ago

Ummm, could you do all Spiranthes in the US? There are several here in TX that I struggle with. Also, is there some sort of a digital 'tip jar' that would work for this?!? ;)

Seriously, great drawing and description of the differences. :)

Posted by sambiology over 6 years ago

I'll try. I began working on a comparison between S. magnicamporum and S. cernua with your comments in mind. Thanks for the support! :)

Posted by arethusa over 6 years ago

Your document is exactly what I needed to make the distinction between Platanthera psychoses and grandiflora. Thank you!

Posted by susan_kielb almost 4 years ago

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