PLATE 14 
Agaricus tabularis: 
A. —A fruiting ring. The vegetation outside of the ring is pure short grass with 
Festuca octiflora and Plantago purshii. At the outer edge of the ring 18 mushrooms 
occur in the portion shown in the photograph. Just back of the fruiting area the 
short grass is dead or dying. In this area there are a few very small plants of P . purshii, 
Lepidium ramossissimum , and Chenopodium incanum. The inside shows a rank growth 
of L. ramossissimum, Lap pula occidental, P. purshii, and Festuca octoflora. Akron, 
Colo., June 14, 1915. 
B. —The mycelium as it appears on the soil mass. So dense is this fungus growth 
that all crevices in the soil are filled with white hyphae. Water penetrates very slowly 
into a dry soil in this condition. Akron, Colo., August 14, 1915. 
C—A trench across a ring of A. tabularis in a Kubanka wheat plot, showing the 
mycelium in the soil. A sketch of this trench is shown in figure 14. The mycelium 
in the ring fills the soil lying from 10 to 30 cm. in depth. The ring is about 4 meters 
wide, and on the inside of this area the mycelium occurs sparingly at a depth ex¬ 
ceeding 30 cm. The mycelium may have grown down as it died above. The soil is 
very dry in the mycelium area, but moist where no mycelium occurs. The available 
water was 0.6 per cent in the mycelium and 11.6 per cent in the soil outside the 
mycelium area. After a rain the soil above the mycelium remained very wet, owing 
to the failure of moisture to penetrate the dry mycelium layer. Only that portion of 
the soil above the mycelium (3 or 4 inches) was moistened by the rain on August 6 
and 7 of 1.89 inches, while the soil in the adjacent areas was wet to a depth of over 
1 foot. Akron, Colo., August 10, 1915. 
