The Plant Kingdom - 607 



Fig. 31-14. Puffballs, another kind of club fungus, growing upon rotting wood. 

 Notice the white strands of the mycelium, which penetrate down into the wood. 

 The mycelium must grow for many weeks before the sporophores (puffballs) ap- 

 pear. (Photo by C. F. Hottes; from The Plant World.) 



poisonous species (commonly called toad- 

 stools). Some of these produce organic toxins 

 of truly high potency. Only an expert, there- 

 fore, should be trusted to gather mushrooms 

 from the field. A single large sporophore 

 from the commercial mushroom, Psalliota 

 campestris (Fig. 31-13), may produce as many 

 as two billion basidiospores, if it is allowed 

 to ripen completely. 



Some of the most devastating crop dis- 

 eases, such as wheat rust (Fig. 31-16) and 

 corn smut (Fig. 31-17), are caused by para- 

 sitic Basidiomycetes. 



The phylogenetic relations of the Eumyco- 

 phyta are somewhat problematical. How- 

 ever, it is clear that the phylum originated 

 at a very early date (Fig. 29-1 1). 



The Deuteromycetes (Imperfect Fungi). This 

 last class of the Eumycophyta serves as a con- 

 venient category into which fungi of obscure 

 relationship may be placed. They are called 

 imperfect fungi because they do not seem to 

 display any sexual phase in the reproductive 

 cycle. Possibly such phases may have ap- 

 peared and were later lost in the course of 



evolution; or perhaps, at least in some cases, 

 sexual phases do exist, but have never been 

 observed by man. In any event, many of the 

 imperfect fungi are parasitic. Moreover, a 

 few of them are responsible for some trouble- 

 some human infections. These include 

 thrush, a mouth and throat infection; sprue, 

 an intestinal inflammation, not uncommon 

 in the tropics; and several skin infections, 

 namely, ringworm, barber's itch, and ath- 

 lete's foot. 



The Lichens. These dual organisms (Fig. 

 10-5) are difficult to classify because each rep- 

 resents a symbiotic association between two 

 species — one a fungus and the other a green 

 alga. There are, however, some 14,000 kinds 

 of lichens, varying in color from the more 

 familiar gray-green forms through a range 

 of yellow, orange, red, brown, and black. 



Various lichens can grow on bare rocks 

 and barren soils; and many can withstand 

 extremes of cold and drought. One kind, the 

 reindeer moss (Fig. 31-18), provides a staple 

 food for the reindeer herds of Lapland; and 

 other kinds penetrate deep into the Arctic 



