454 YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 

 HOW TOADSTOOLS (INCLUDING MUSHROOMS) GROW. 



In the case of persons for whom this paper is written, it is unnec- 

 essary to consider the question of how far we are justified in judging 

 from analogy alone, since the main point is to learn to recognize a 

 certain number of the most common edible species and to distinguish 

 them from poisonous species which resemble them. The toadstools 

 and mushrooms all belong to the group of fungi known as Hymeno- 

 mycetes ; and before proceeding to speak of the different species which 

 we are to consider, it will be well to state briefly some points common 

 to the whole group. 



The toadstools, including mushrooms, first appear on the surface 

 of the ground, on the bark of trees, or on other substances in the form 

 of small, solid balls, which gradually enlarge and at length shoot up 

 into a stem, or stipe, bearing at its summit the umbrella top, or i^ileus, 

 which is at first closed around the stalk like a closed umbrella and 

 then expands more or less widely according to the species. When 

 small and just beginning to open, the growths are called buttons, as 

 in the so-called button mushrooms usually imported in cans from 

 France. The young buttons arise from a complicated mass of fine, 

 colorless threads in the ground, in logs, dung, or other substances. 

 The mass of threads is known to cultivators of mushrooms as the 

 spawn and to botanists as the mycelium, each individual thread being 

 called a hypha. 



It is often said that toadstools grow in a night, but such is not the 

 case. After the button has fully formed it may develop into the 

 mature toadstool very rapidly, but the development of the button 

 from the spawn takes usually considerable time, and weeks, months, 

 or even years may elapse before the spawn comes to the surface and 

 forms the young button. If we compare the functions of the spawn in 

 the ground and of the toadstool above ground with those of the roots, 

 trunk, branches, leaves, and fruit of a plant like an apple tree, we 

 find that in the toadstool the spawn itself performs all the functions 

 of the root, branches, and leaves of the apple tree, and that the toad- 

 stools are really only the fruiting part of the fungus, corresponding 

 to the apples themselves. If we imagine an apple tree to have its 

 trunk, branches, and leaves buried in the ground, leaving only the 

 apples themselves standing above the ground, and then to have the 

 buried parts changed into a mass of fine threads, we shall have some- 

 thing similar to what is found in the case of a toadstool ; in other words, 

 all the absorption and assimilation of food, all the purely vegetative 

 functions, are performed by the spawn, while the toadstool, like the 

 apple, is only a reproductive bodj^ — the apple containing seeds, the 

 toadstool spores (microscopic dust-like bodies, which correspond in 

 function to seeds). 



