Subject: Re: Orchids and epiphytes

From: Elaine Ingham <[email-masked]>
Date: Sat, 19 Apr 2003 13:50:00 -0400

Orchids and other epiphytes are interesting cases, because they are parasites of other plants.  They have to be connected by specific kinds of mycorrhizal fungi to the host plant.

The host plant doesn't have to be alive, it can be dead plant material that these plants parasitize.  Therefore the peat moss, dead wood, wood chip media for growing orchids.  Quite often, orchids grow in the organic matter that is caught in the crotches of trees.  I am not enough of an expert on the subject to know if the orchid mycorrhizae mine just that organic matter, or if they parasitize the tree as well.

But you have to have the orchid mycorrhizal fungi to grow orchids.

So, what is in the root system of orchids?  Well, root system?  Do they really have one?  OK, the mycorrhizosphere then?  If you count the fungi as separate from the plant, then the "root system" is fungal.  If you count the mycorrhizal fungi as part of the root, then the rhizosphere is about equal fungi to bacteria.

Hope this helps -

Elaine Ingham
President, Soil Foodweb Inc.
SFI Corvallis, OR
SFI Port Jefferson, NY
SFI Lismore, NSW, Australia
SFI Hilversum, The Netherlands
SFI Cambridge, New Zealand
www.soilfoodweb.com