Journal of Agricultural Research 
Vol. XI, No. 5 
I98 
zones: Beginning at the center (o, fig. 1) the first zone was an internal 
one (2) where the phanerogamic vegetation contrasted sharply with the 
normal; the second zone (3) a middle one where the herbage was with¬ 
ered and where the fruits of M. oreades occurred; and finally an external 
zone (4) larger than (2) the internal zone, where the vegetation was 
greener and taller than the inside (1) or the outside (5). 
Munch (1914) described and illustrated a ring formed by Agaricus 
(Clitocybe) maximus which had a stimulated zone outside as well as 
inside a well-defined dead zone. It differed from the rings described 
by other investigators in that the dead zone was lined with fruiting 
bodies both on the exterior and interior sides. 
Fairy rings caused by fleshy fungi may be divided into types on the 
basis of their effect on the vegetation. It is apparent from a review of 
the literature that the effect of the various fungi on the vegetation varies 
greatly in different locations as the probable result of the different 
climatic and weather conditions. 
In eastern Colorado the following types of fairy rings may be distin¬ 
guished: (1) Those in which the vegetation is killed or badly damaged, 
caused by Agaricus tabularis; (2) those in which the vegetation is only 
stimulated, caused usually by species of Calvatia, Catastoma, Tycoperdon, 
marasmius, etc.; and (3) those in which no effect can be noted in the 
native vegetation, caused by Lepioia spp. 
KINGS MARKED BY A ZONE OE DEAD VEGETATION 
RINGS FORMED BY AGARICUS TABUUARIS 
The rings formed by Agaricus tabularis Peck vary in size from a few 
meters to 70 meters across. These rings are often complete and circular, 
the advance in all directions having been nearly uniform (PI. 13, A; 18; 
20; 30, A). More often, however, the ring is broken at certain points, and 
the larger rings are usually formed by a series of arcs which do not come 
into contact with each other but which show approximately equal radii 
(%• 2). 
In figure 3 is given a diagram and in figure 4 a bisect of a typical ring 
formed by Agaricus tabularis . At A the zones are shown as they are 
distinguished during a period favorable for the growth of the fungus 
and the production of fruiting bodies. (PI. 13, A; 14, A; 19.) The ring 
consists of a series of three zones surrounding an area of normal short grass 
sod, which constitutes the inside of the ring (1). Next to this area occurs 
a broad zone differing from the natural sod in botanical composition, in 
the more luxuriant growth, and in the deeper green color of the vegetation. 
This is the inner stimulated zone (2). This wide green zone is the most 
prominent part of the rings in spring or in wet seasons. The bare zone (3) 
is not as broad as the inner stimulated zone and is somewhat more irregu¬ 
lar. In this zone the vegetation is often entirely dead, but in many 
