CHAPTER XXXV 

 FUNGI IMPERFECTI 



As the classification of fungi rests upon the life cycle of the individual 

 species, of the various spore forms, only the asci and basidia, which in 

 their character as gonotoconts play an important part in the cycle, are 

 largely used as a means of classification. There is no place in this system 

 for the imperfect forms which must be separately discussed until the 

 group to which the life cycle belongs, has been discovered. In this 

 connection, we may recall the Oedocephalum type which appears in the 

 life cycle of the Mucoraceae in the Phycomycetes (Fig. 60) of the Peziz- 

 aceae in the Ascomycetes (Fig. 224), and of the Polyporaceae in the 

 Basidiomycetes (Fig. 288). Since for practical purposes one must name 

 and classify these imperfect forms somewhere, they have been grouped as 

 Fungi Imperfecti (Fungi with incomplete or incompletely known life 

 cycles). It is clear that in this group there can be no natural families and 

 genera in the sense of phylogenetic unities, but only artificial groups of 

 forms. Cytologically these imperfect forms are mostly haplonts; the 

 only regular diploid imperfect form, the uredinium of the rusts, because 

 of its characteristic structure immediately shows its systematic position. 



The older classification of Fungi Imperfecti, developed by Saccardo 

 in his Sylloge Fungorum, proposes three main groups: the Hyphomycetes, 

 in which the conidiophores arise singly on mycelium, or, at most, are 

 joined into coremia; the Melanconiales, in which they are formed on stro- 

 mata (acervuli) ; and the Sphaeropsidales, in which they are inclosed in 

 pycnia. Obviously this classification is only a makeshift and is encum- 

 bered with all sorts of misfits. For example, Pestalotia versicolor (P. 

 Palmarum) forms solitary conidia on hyphae, in nutrient solution (Fig. 

 404, 2) and in this stage must be placed in the Hyphomycetes. Under 

 more favorable conditions of nourishment, the hyphae intertwine to 

 stromatic layers which may become pseudoparenchyma by the reciprocal, 

 polyhedral flattening of the cells; the conidia arise either directly on this 

 stroma or on single hyphae; occasionally the tissue arches over to a kind 

 of pycnium, which, however, is still formed of hyphal tissue and is usually 

 called pseudopycnium. In this stage, the fungus must be assigned to the 

 Melanconiales. Finally, under certain conditions, one can obtain the 

 type of fructification ordinarily seen in Nature, the pycnia; in this 

 stage the fungus undoubtedly belongs to the Sphaeropsidales. Where 

 we do not know the ontogenetic relations, a fungus may be placed in 



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