FIELD BOOK OF COMMON GILLED MUSHROOMS ! 



The surface may be smooth, dry, sticky or perhaps covered 

 with scales (38 Frontispiece). 



If the cap has a knob protruding from its center it is said 

 to be umbonate (15) (umbo — a knob). The opposite form, 

 that of a little pit, sometimes occurs (93), in which case the 

 cap is said to be umbilicate (provided with a navel). 



Where no mention in this book is made of a mushroom's 

 form, it is assumed that the cap is of a convex form when young 

 and is plane or nearly so when mature. When reference is 

 made to the cap of a mushroom, a mature specimen is meant 

 unless otherwise specified. 



Other features of caps are mentioned in the key under the 

 heading, "Cap, Form of." 



Gills — The gills (lamellse) are thin, knife-like blades at- 

 tached by their upper edge to the under surface of the cap and 

 extending like the spokes of a wheel (or ribs of an umbrella) 

 from the stem to the margin. They always grow with their 

 flat surfaces vertical. Upon these gill-surfaces are formed 

 the spores that are cast off for the purpose of propagation. 



In form gills may be broad or narrow, varying with different 

 species. An important distinction is made between gills that 

 extend to the stem (116, 118) (adnexed), those that are 

 attached broadly to it (adnate) (95, 96) and others that do 

 not reach it but are said to be free (85). Gills that run dov/n 

 the stem are termed decurrent (15) ; those that are notched in 

 their edge near the stem (123), are known as sinuate or emarg- 

 inate. 



Not always are gills thin; mushrooms of the type of Can- 

 tharellus have blunt narrow gills resembling coarse leaf- veins. 

 Again, the free edge of the gills, instead of being knife-edged, 

 as is usually the case, may be notched like a saw (81) (serrate) 

 or wavy. 



The spore-bearing surface of the gills is called the hymen- 

 ium, which, in some cases, extends also across the under 



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