Subject: Orchids and Mycorhyza

From: [email-masked] (BobBank)
Date: 29 Mar 1995 20:59:47 -0500

Hello.

I'm a student doing a project on the relationship between mycorhyzal fungi
and orchid seedlings.  I have read that in some cases the relationship is
very delicate, the orchid only germinating if combined with the exact
species of mycorhyza.  Please direct me to some information sources, or
better yet, if you have any information yourself I would greatly
appreciate it.  Thank you for your time.

Bob

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From: [email-masked] (Andrew Poynter)
Date: 3 Apr 1995 10:46:57 GMT

Hi Bob,

The staff on the Sainsbury's Orchid Project, at the Royal Botanic Gardens Kew, Richmond, Surrey, UK, 
may well be able to help. They have a page on the WWW, with E and tel. numbers. I will try to dig out a few names
for you in the mean time.

Andrew Poynter

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From: [email-masked] (Andrew Poynter)
Date: 3 Apr 1995 12:04:26 GMT

In article <[email-masked]>, [email-masked] (Andrew Poynter) says:

Follow up:  Address for you: 
The Enquiry Unit, Royal Botanic Gardens Kew, Richmond, Surrey, TW9 3AB ,UK tel 0181-332-5622 
http:/www.rbgkew.org.uk/ E-mail; [email-masked]

Andrew Poynter

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From: [email-masked] (En ring til aa herske)
Date: 4 Apr 1995 08:58:18 -0700

unsubscribe plant-biology

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From: [email-masked] (Jeffrey Kirby)
Date: 4 Apr 1995 14:40:02 GMT

The answer to your question is yes. A lot of plants have symbiotic 
relationships with mycorrhizal fungus, usually a Rhizoctonia species (I 
think). Many orchids cannot germinate without this because the orchid 
seed has no endosperm or other food reserves. The fungus acts to break 
down complex nutrients in the surrounding media and then transport the 
results (such as carbohydrates and amino acids) into the plant, which can 
then grow. It's an endomycorrhizal fungus, not ecto (endo meaning the 
fungus is inside a cell of the orchid). Humans avoid this relationship by 
sowing orchid seeds on sterile medium that has all the nutrients they need 
in a form they can absorb. Some orchids have not been successfully raised 
this way (I'm pretty sure). Usually it's the terrestrial species that are 
hardest to raise without the fungus, and in nature, such species as 
Corallorrhiza species (which are leafless saphrophytes in North America) 
need the fungus all of their life to break down surrounding materials.

Most orchid books will give you an explanation like this, as will most 
general biology texts. Try:

Arditti, Joseph. 1992. _Fundamentals of Orchid Biology_. New York: John 
Wiley and Sons.

-J

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Jeffrey A. Kirby -- Jester of Xanadu -- [email-masked]

I'd like to dedicate this .sig to all my fans out there, and tell you, 
"You're wrong. I am just a fruit."