408 VEGETABLE FORCING 



Fig. 147. Wooden mushroom houses at Kennett Square, Pa. 



Botanical characteristics. The cultivated mushroom 

 so familiar to growers in the United States is botanically 

 known as Agaricus campcstris. It consists of a stalk or 

 stipe, varying in height from 2 to 5 inches, and in 

 diameter from l / 2 inch to 1 inch. The top or expanded 

 part of the mushroom is known as the "cap" or "pileus" ; 

 this varies greatly in thickness and diameter, according 

 to variety, stage of growth and condition under which it 

 is grown. Varietal variations are rather marked, the caps 

 of some being whitish, while others are creamy white or 

 perhaps brown. The leaflike or gill-like projections on 

 the under side of the cap are termed gills or "lamellae'' ; 

 these, for a time, are pink in color in the white or cream- 

 colored species, but they subsequently turn brown or 

 brownish black. The dark-colored spores are borne on 

 the gills, and they serve as the reproductive bodies of the 

 mushroom. 



Spores are the normal propagative bodies of this fungus, 

 but growers do not use them directly in the production of 

 mushrooms, although under favorable conditions they 

 will germinate and ultimately produce a threadlike 

 growth termed the "mycelium." 



Where to grow mushrooms. The most extensive 

 mushroom plantations in the world are in France. The 

 city of Paris, built of stones largely taken from quarries 



