CHAPTER I 



FORM AND CHARACTERS OF THE MUSHROOM. 



Value of Form and Characters. The different kinds of mushrooms 

 vary in form. Some are quite strikingly different from others, so 

 that no one would have difficulty in recognizing the difference in 

 shape. For example, an umbrella-shaped mushroom like the one 

 shown in Fig. i or 8i is easily distinguished from a shelving one 

 like that in Fig. 9 or 188. But in many cases different species vary 

 only slightly in form, so that it becomes a more or less difficult 

 matter to distinguish them. 



In those plants (for the mushroom is a plant) where the different 

 kinds are nearly alike in form, there are other characters than mere 

 general form which enable one to tell them apart. These, it is true, 

 require close observation on our part, as well as some experience in 

 judging of the value of such characters ; the same habit of observa- 

 tion and discrimination we apply to everyday affairs and to all 

 departments of knowledge. But so few people give their attention 

 to the discrimination of these plants that few know the value of their 

 characters, or can even recognize them. 



It is by a study of these especial characters of form peculiar to 

 the mushrooms that one acquires the power of discrimination among 

 the different kinds. For this reason one should become familiar with 

 the parts of the mushroom, as well as those characters and markings 

 peculiar to them which have been found to stamp them specifically. 



Parts of the Mushroom. To serve as a means of comparison, the 

 common pasture mushroom, or cultivated form {Agaricus campestris) , 

 is first described. Figure i illustrates well the principal parts of the 

 plant ; the cap, the radiating plates or gills on the under side, the 

 stem, and the collar or ring around its upper end. 



The Cap. The cap (technically the pileus) is the expanded part 

 of the mushroom. It is quite thick, and fleshy in consistency, 

 more or less rounded or convex on the upper side, and usually white 

 in color. It is from 1-2 cm. thick at the center and 5-10 cm. in 

 diameter. The surface is generally smooth, but sometimes it is 

 torn up more or less into triangular scales. When these scales are 

 prominent they are often of a dark color. This gives quite a differ- 

 ent aspect to the plant, and has led to the enumeration of several 



