CHAPTER IV: THE KEY 



WHAT A KEY IS, AND WHY A NAME IS DESIRABLE 



A key in the study of botany is a guide by which a student 

 may trace a specimen until he finds a name for it. Having found 

 a name, he may learn from books or from friends what is known 

 of its habits of growth, of its value as a food or drug, whether 

 it is harmful or harmless, whether it is to be protected or 

 whether war is to be waged against it. He may learn whether 

 it has figured in history or the myths, and how the poets and 

 artists viewed it, and may perhaps learn to see it with their 

 eyes. He may watch similar specimens as they grow, and may 

 add the results of his observations to the facts already recorded 

 about his specimen. 



HOW A KEY FOR FUNGI IS MADE, AND WHY IT IS DESIRABLE 



In the first place, only such plants are considered as grow 

 from spores and have no leaf-green. (The spore characteristic is 

 one the amateur must decide upon either by seeing the spores 

 or by inferring their existence from the fact that seeds do not 

 appear.) There are some thirty-five thousand species of fungi 

 known to botanists, so that it would be impossible to find a 

 name for a specimen if one had to read at random until the right 

 description for his specimen was found; but since all of these 

 plants may be put in one or another of three groups, on account 

 of certain points of resemblance which they have in common, 

 and since these three groups may each in turn be divided and 

 subdivided, one may, by selecting groups rather than individual 

 specimens, find a short path to the name desired. The three 

 primary groups, called classes, are made as follows : 



The first contains many mould-like fungi which resemble 

 one another in microscopic characters. 



The second contains other mould-like fungi and many con- 



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