PLATE 30 
A. —The effect of a ring of Agaricus tabularis on the native vegetation. In this 
ring the short grass is dying or dead, but Gutierrezia sarothrae is a little larger and much 
greener in color than either outside or inside the ring. Akron, Colo., July 25, 1909. 
B. —A ring of Catastoma subterraneum. The only outward evidence of the presence 
of this fungus is the stimulated growth of Plantago purshii and the slightly deeper 
green of the short grasses. The mycelium is not easily distinguished in the soil, 
although the fruiting bodies are just breaking through the soil. Akron, Colo., August 
16, 1915. 
C. —A very small ring apparently caused by a fungus but marked only by a more 
luxuriant growth of Festuca octoflora . Akron, Colo., June 15, 1915. 
