54 



THE AMERICAN BOTANIST 



they haA^e no seeds but are propagated by spores which serve 

 the same purpose. A spore falling in a proper situation for 

 growth, soon gives rise to a tangle of threadlike structures 

 which forms the body of the plant. This substance made into 

 bricks and dried, is the mushroom "spawn" sold by the dealers. 

 At intervals little rounded knobs form upon the mushroom 

 threads and later develop into the familiar umbrella form. If 

 the "spawn" is exposed to unfavorable conditions, it is said to 

 be able to wait for years for a chance to fruit. The mushroom, 

 it may be said, is only the fruiting part of the plant, compar- 

 able in a general way with the flowering spike of the century 

 plant, although not homologous with it. On the underside of 

 the umbrella-like cap are numerous radiating plates called gills 

 which support the structures on which the spores are produced. 

 By cutting off this cap and laying it, gills down, on a clean 

 piece of paper, there will be produced in a few hours a "spore- 

 print" in exact duplication of the arrangement of the gills, and 

 due to the shedding of the numerous spores. Usually the 

 spores are of the same color as the gills, although in some 

 species they are not. 



The mushrooms are classed with the higher fungi. Among- 

 their poor relations are numbered the rusts, smuts, blights, 

 mildews, molds and bacteria. The puff-balls and morels are 

 also nearly related. Although so low in the scale of plant life 

 these constitute a very respectable part of the vegetable king- 

 dom, since more than forty thousand species have been de- 

 scribed. 



There are about two thousand species of mushrooms in 

 America. Some of these are known from only a single state, 

 while others are distributed throughout. Formerly all were 

 classed in the genus Agaricus, but owing to the differences 

 which exist in such a multitude, thev are now placed in five 

 groups according to whether their spores are white, pink, yel- 

 lowish, brown or black. Each of these groups contains one 



