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A TEXTBOOK OF THEORETICAL BOTANY 



Development of the Sporophore 



The fruiting body of the mushroom arises as a tiny knot of hyphae, which 

 become aggregated together on the subterranean myceHum. It assumes a 

 more or less elUptical shape and, at an early stage, a rudimentary ring-shaped 

 channel appears around that part which will eventually produce the stalk. 

 This channel develops into a hollow which will later form the gill cavity 

 (Fig. 315). From the roof tissue of this cavity, w^hich will eventually form 



Pileus 



Gill clefts 



Partial veil 

 Gill cavity 



Stipe 



Fig. 315. — Psalliota campestris. Vertical section through 

 a young fruiting body showing the development of 

 the gill ca\"ity. 



the cap, slender, pointed, downwardly growing hyphae push into the gill 

 cavity and form the gills, while the cavity itself enlarges in size. These gills 

 form a series of radiating plates. 



At an early stage the cap is enveloped in a loose-meshed tissue which 

 extends downwards to the stem. The extent of this tissue varies in different 

 genera. In some, like Amanita, it may extend right over the whole of the cap 

 and stalk forming a universal veil, but in Psalliota and in a number of other 

 genera the veil extends only into the stalk below the gills and is termed a 

 partial veil. In many other genera no veil is formed and the gill cavity is, from 

 the first, exposed to the exterior. 



As the gills develop the stalk or stipe begins to elongate, particularly in 



