3S6 THE BASIDIOMYCETES 



or toadstools. The vegetative portion of a typical one, Amanita, 

 exists in decaying leaf mold as white threads or strands. Small, 

 compact white spherical bodies (buttons) that may be found 

 alonof these strands constitute the initials of fruit bodies. If thev 

 are properly cut in half, it mav be observed that a membrane, the 

 universal veil, invests the entire button and that the central axis is 

 occupied by the developing stipe with the pileus or cap at the 

 top. The edges of the cap curve downward. A circular chamber 

 soon appears, surrounding the stipe toward the upper end. This 

 chamber enlarges as development proceeds, and lamellae or gills, 

 radiately arranged, grow into it. The edges of the gills approach 

 the stipe but are separated from it by a thin tissue, the veil, which 

 connects the gill edges and surrounds the stipe. At the approach 

 of maturity the stipe elongates, and the gills open in an umbrella- 

 like fashion. As they do, the universal veil is ruptured but per- 

 sists as a cup (volva) at the base of the stipe and as scales on the 

 upper surface of the pileus. The veil covers the gills below and 

 eventuallv ruptures to leave a ring (annulus) around the stipe. 

 As the cap expands, the gills, arranged like spokes in a wheel, 

 hang with their edges directed downward. The surface of the 

 gills is the hymenium (fruiting laver), which consists of a pali- 

 sade of club-shaped basidia. Each basidium bears four basidio- 

 spores that are discharged forcibly into the space between gills. 

 Air currents disseminate the basidiospores. 



The student soon learns to distinguish certain of the more com- 

 mon genera of mushrooms. Amanita, Amanitopsis, and Lepiota 

 are white-spored with gills free from the stipe and can be recog- 

 nized because Amanita possesses a volva and an annulus, Amani- 

 topsis a volva only, and Lepiota an annulus only. Russula and 

 Lactarius, also white-spored, have firm, thick caps and short, thick 

 stipes that are spongy-stuffed within. They differ in that Lac- 

 tarius possesses "milk" that exudes when the pileus is injured and 

 mav rather quickly become yellow, blue, orange, pink, greenish, 

 or gray. Clitocybe and Tricholoma are white-spored, do not 

 possess an annulus or a volva, and have fleshy, fibrous stipes with 

 a cartilaginous rind. The gills of Clitocybe are decurrent or 

 broadly adnate; of Tricholoma, sinuate. Cantharellus has thick, 

 decurrent gills that are forked. Cortinarius is ochre-spored and 

 possesses a cobweb-like veil. Pleurotus and Claudopus have 



