SIMPLE LIFE 



141 



asexual 

 ■spores 



germination 



~-Ki 



spore 



producer 

 'L(sporangium) 

 > 



vegetative 

 ■stage 



gernnination 



sexual 

 spores 



gamete 

 production 



fc( y 



resting stage 

 (spore or sporangium) 



Rgure 8.11 Algol fungi life cycle as typified by the bread mold, 

 Rbizopus. 



Life cycle: mostly of a single type involving a 

 sexual and an asexual cycle united in a vegetative 

 mycelium (Figure 8.11). 



CLASS ASCOMYCETES (Sac Fungi) 



Diagnosis: cellular (often multinucleate) and 

 usually filamentous; mycelium when present with 

 individual cells regularly defined by chitinous cell 

 walls; typical structure a sexual cycle spore (asco- 

 spore) produced in a sac-like ascus that forms a 

 definite number, usually eight, of ascospores (sporan- 

 gium gives rise to an indefinite number); many have 

 a multicellular, often visible, sexual fruiting body 

 often approaching tissue organization; flagellae 

 absent (Figure 8.12). 



Structure: unicellular forms (mostly yeasts) have 

 little or no mycelium; filamentous forms have a true 

 mycelium, often organized into conspicuous fruiting 

 bodies; visible forms are generally powdery, moldy, 

 or some form of macroscopic fruiting body; the vege- 

 tative mycelium may be a compact, cushion-shaped, 

 visible structure. 



Life cycle: assumes many complex forms (Figure 

 8.13); major types involve a sexual and an asexual 

 cycle (generally with the production of hyphae during 

 the sexual phase as well as the vegetative mycelium). 



a strictly sexual cycle with ascospores forming the 

 vegetative mycelium which in turn forms "gametes," 

 and two major variations without any vegetative 

 mycelium. 



CLASS BASIDIOMYCETES (Club Fungi) 



Diagnosis: cellular and usually filamentous as in 

 Ascomycetes; typical structure a sexual cycle spore 

 (basidiospore) produced in a vaguely club-like ba- 

 sidium that forms a definite number, usually four, of 

 basidiospores; basidium may form a vegetative my- 

 celium directly (mostly in smuts); mycelium often 

 more developed than that in Ascomycetes; often with 

 a fruiting body that approaches tissue organization; 

 flagellae absent (Figure 8. 14). 



Structure: species without a fruiting body usually 

 are observed as a colored powder (rusts) or black 

 powder (smuts), the spores; gross form of fruiting 

 bodies vary but are similar to those found in Ascomy- 

 cetes. 



Life cycles: cycles are extremely complex, but can 

 be reduced to four major types (Figure 8.15); two 

 types occur in the fruiting-body-producing forms, 

 (the so-called higher club fungi), one type in the rusts 

 (many of which are parasitic upon two different 

 plants during their life cycle), and the last type in 

 the smuts. 



MUSHROOMS VS. TOADSTOOLS 



Contrary to popular belief, there is no way of 

 being sure that a particular fleshy fungus is a mush- 

 room or a toadstool. That is, one cannot be certain 

 whether a particularly shaped member of the fleshy 

 club fungi is nonpoisonous or poisonous. Certain 

 species of these fungi may be perfectly edible at some 

 times and poisonous at others. However, there are 

 certain distinctive, always safe mushrooms that one 

 can eat and others that are always poisonous. There- 

 fore, the so-called distinction between mushrooms 

 and toadstools has no real meaning. Although there 

 is some confusion in the application of common 

 names to club fungi, most of ihe fleshy club fungi called 

 mushrooms can be assigned to one of a few growth 

 forms (Figure 8.16). However, the same growth form 

 can occur in three different families, the pore (with 

 fine holes or teeth), gill (with blade-like gills), and 

 tooth (with pricks or tooth-like structures) fungi. 

 Also, these mushrooms belong to the same or- 



