30 



ACADEMIC BOTANY. 



54. The Mushrooms include many genera : Clavaria (Fig. 

 22, 7), Hydnum, Boletus, Polyporus, and' others, besides 

 the true Mushrooms, Agaricus (Fig. 22, 4, 5, e), and Ama- 

 nita. The fairy- 

 rings, so venerated 

 by the superstitious 

 and so long a puzzle 

 to scientists, are the 

 work of mushrooms. 

 Several species — 

 Agaricus oreades 

 (Fig. 22, 6), A. coc- 

 cineus, and others — 

 have a tendency to 

 grow centrifugally 

 in excess. The spot 

 on which they grow 

 soon becomes unfit 

 for their support, and 

 they spread outward 

 with almost mathe- 

 matical precision, 

 leaving bare rings. 



These rings at first produce nothing, but they eventually 

 become fertile from the decayed remains of the mushrooms. 

 Abundant grasses then spring up, which form the fairy- 

 rings. These rings grow larger continually as the mush- 

 rooms spread, until some obstacle breaks the circle. 



55. The vegetative part of the Fungi is called Mycelium 

 (pi. mycelia), from the Gr. myhos, mw/cos, mushi'oom (Figs. 

 19, 20). This consists of elongated cells called hyphce, 

 which are isolated or collected in threads, or united into a 

 web or membrane (hymen). The mycelium is sometimes 

 barely visible, but often it is conspicuous, sometimes root- 

 like. The flower-cluster (called Receptacle) grows out of 

 this mycelium ; in the Mushroom it is called Pileus, or cap. 

 When there is a flower-stalk it is called a Stipe, as in the 

 Moulds (Figs. 19, 20) and the Mushrooms (Fig. 22). The 

 surface on which the flowers grow in mushrooms is the 

 Hymenium, or membrane. It covers the Gills {lameU(s) on 



Fig. 22.-4, St. Georsje's Agaric {AgarUms Georgii; d, 

 young. 5, Common Mushroom {A. campealris) ; e, young, 

 (i, Fairy-ring Mushroom {A. oreades) ; f, young. 7, 

 Clavaria phi^loidee; g, young. 



