DEVELOPMENT OF PLANTS 247 



While the majority of the 5,000 species of the family are edible, 

 some of them contain the most deadly poisons. No rule can be 

 given that will enable the collector to separate these fungi into 

 the two mythical groups of poisonous toadstools and edible mush- 

 rooms. Each species must be known individually before it is 

 safe to use them for food. All forms with a volva should be 

 most carefully identified, because this is a feature of the deadly 

 amanitas (Fig. 167), which are among the most poisonous plants 

 known. 



The remaining orders of Basidiomycetes are characterized by 

 the concealment of the basidia in cavities and are for this reason 

 collectively known as the Gasteromycetes, meaning stomach 

 fungi. Among the more common orders may be mentioned: 



97. Order d. Lycoperdales or Puff Balls. — These familiar 

 fungi are developed, as in the Agaricales, on strands of the 

 mycelium, which often form extensive net-like threads in rotten 

 stumps, logs, sawdust and humus (Fig. 171). The puff balls 



Fig. 171. Cluster of common puff balls, Lycoperdon. At left three older 

 ones have opened, permitting discharge of basidiospores. 



vary in size from a pea to over a foot in diameter. When young, 

 they consist of white cheesy masses of hyphae which form in 

 the interior of the puff ball a series of irregular cavities lined with 

 basidia and on the exterior, a rather firm skin or periderm (Fig. 

 172). At maturity, the inner hyphae break up, leaving only a 

 dusty mass of spores and in somes cases firmer hyphae, the capil- 

 litium. The skin ruptures in various ways; often by one or 

 more pores at the top, and the least touch now causes the spores 

 to sift out in smoke-like puffs, hence the popular name of pufi 



