Subject: Why do mushrooms ...

From: [email-masked](Docktor Crow Goodfellow )
Date: 1 Aug 1996 01:12:45 GMT

A friend of mine said that some mushroom grow in rings of perfect
circles (that is, multiple mushrooms forming a circle).  Is this true? 
For all mushrooms?  For some?  If it is true, why is it so?

Please respond via mail.  Thanks.

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From: [email-masked]
Date: Thu, 01 Aug 1996 00:43:52 -0700

>Please respond via mail.  Thanks.

I've heard them called "fairy rings," but have never seen any little
fairies dancing around the ones I have in my prairie grass. ;)  I suppose
that the fruit (mushrooms) simply grows at the edge of the advancing
"root" (the disc shaped mycelium). Anyhow, the diameter does enlarge quite
noticeably every year. I have another variety of huge mushrooms in a ring
approximately 60 feet in diameter in the woods. Some of these can be six
to eight inches tall with a cap of the same diameter.

-- 
Jim
[email-masked]

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From: JeremyBrowne <[email-masked]>
Date: Thu, 01 Aug 96 14:50:01 GMT

> For all mushrooms?  For some?  If it is true, why is it so?

Some fungi do indeed grow in rings, but perfect may not be quite accurate!
Two species known for producing rings are Tricholoma Gambosum 
(St. Georges Mushroom - also known as Calocybe Gambosum or Lyophyllum georgii)
and Marasmius Oreades (Fairy Ring Champignon).

Myths ascribe the rings to fairies, witches, the devil dragons etc. but:
"Fairy rings" (typically in three concentric rings) are caused by mycelium  
of fungi growing from a central starting point. As the mycelium grows, 
it produces changes in the organic matter of the soil. Ammonia is 
liberated and produces nitrates or ammoniacal salts, manuring 
the vegetation, & stimulating its growth. 

As the mycelium increases, it fills the air spaces in the soil so that rain-
water has difficulty in percolating, at a time when the increased vegetation
is making greater demands on the available water. This causes localised 
drought and the plants die, leaving a bare circle. The part behind dies 
off and water can now panetrate the soil and the dead fungus becomes food
for the plants which invade the bare area and so on. Obviously the ring 
widens year on year.

-- 
Jeremy Browne, Hampshire, UK
Shaking Hands BBS, Fidonet 2:252/160