13:> STUDIES OF AMERICAN FUNGI. 



crop of mushrooms. But around the edge of the spot the mycelium 

 or spawn still exists, and at the beginning of the next season it starts 

 into growth and feeds on the available food in a zone surrounding 

 the spot where it grew the previous year. This second year, then, 

 the plants appear in a small ring. So in succeeding years it advances 

 outward, the ring each year becomes larger. Where the plants 

 appear only in the arc of a circle, something has happened to check 

 or destroy the mycelium in the remaining arc of the circle. 



It has been noted by several observers that the grass in the ring 

 occupied by the mushrooms is often greener than that adjoining. 

 This is perhaps due to some stimulus exerted by the mycelium of the 

 fungus on the grass, or possibly the mycelium may in some way 

 make certain foods available for the grass which gives an additional 

 supply to it at this point. 1 have as yet no photograph of the fairy 

 ring mushroom, and the few plants illustrated here (Fig. 126) are 

 from pen drawings by Mr. Rathbun from some of his color sketches. 

 Illustrations of some fme large rings formed by this fungus appeared 

 in circular No. 13 by Mr. Coville, of the Division of Botany in the 

 U. S. Dept. Agr. 



Marasmius cohserens (Fr.) Bres. {Mvcena cohcTrens Fr. Collybialach- 

 iiophylla Berk. Colly bia spiiiiilifem Pk.) — This plant grows in dense 

 clusters, ten to twenty individuals with their stems closely joined 

 below and fastened together by the abundant growth of threads from 

 the lower ends. From this character the name cohvrens was derived. 

 The plants grow on the ground or on very rotten wood in woods dur- 

 ing late spring and in the summer. The plant is not very common 

 in this country, but appears to be widely distributed both in Europe 

 and here, having been collected in Carolina, Ohio, Vermont, New 

 York, etc. The plants are 12-20 cm. high, the cap 2-2.5 cm. broad, 

 and the stem 4-7 mm. in thickness. 



The pileus is fleshy, tough, convex or bell-shaped, then expanded, 

 sometimes umbonate, or in age sometimes the margin upturned and 

 more or less wavy, not viscid, but finely striate when damp, thin. 

 The color varies from vinaceous cinnamon to chestnut or light leather 

 color, or tawny, paler in age, and sometimes darker on the center. 

 The gills are sometimes more or less crowded, narrow, 5-6 mm. broad, 

 adnate, but notched, and sometimes becoming free from the stem. 

 The color is light leather color, brick red or bay, the color and color 

 variations being due to numbers of colored cystidia or spicules scat- 

 tered over the surface of the gills and on the edge. The cystidia are 

 fulvous, fusoid, 75-90 ^long. The spores are oval, white, small, 6x 3//. 

 The stem is long and slender, nearly cylindrical, tapering some- 



