Voyria tenella Hook., Gentianaceae

September 16, 2010

One of the flowering plants that have abandoned photosynthesis but is not a haustorial parasite is Voyria, Gentianaceae, that I and my co-collector Louro have discovered on yesterday’s collecting trip to the nearby patch of the virgin Atlantic forest at Imbé (Entre Rios, Bahia, Brazil).  According to  Daniel L. Nickrent of Southern Illinois University at Carbondale, IL, “these plants are frequently mistaken for parasitic plants but are more accurately called myco-heterotrophs (also sometimes mycotrophs).  [They] … can live without photosynthesis because they have established a coevolutionary relationship with a mycorrhizal fungus that is attached to the root of a photosynthetic, woody plant. So, there is a three way association such that nutrients (carbon) flow from plant root, to mycorrhizal fungus to the myco-heterotroph. … The mycotrophs don’t directly invade the photosynthetic “host” roots but indirectly obtain nutrients via the intermediate fungus. … [M]yco-heterotrophs are frequently mistakenly called saprophytes.  There are no true saprophytes in the angiosperms.  Only fungi can directly utilize dead organic material.”

Specimens of mycotrophs need to be preserved in 70% alcohol. Luckily, we were prepared for such an eventuality.

See http://www.parasiticplants.siu.edu/Mycotrophs/Mycotrophs.html and http://www.newphytologist.com/view/0/virtspecissueMyco.html for further information.

Symbiotic seed germination is widespread in orchids.

PS. Thanks go to Dan Nickrent for the identification of the genus and Paul Maas for pinpointing the species.

Paul Maas is the author of a monograph on Voyria (Maas, P. J. M. & P. Ruyters. 1986. Voyria and Voyriella  (saprophytic Gentianaceae). Flora Neotropica Monograph 41. The New York Botanical Garden, Bronx, NY).

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