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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