FUNGI IMPERFECT! : THE IMPERFECT FUNGI 573 



duction may be separated in time and substratum, many fungi have been 

 described under different names according to whether one or the other 

 stage was studied. As time goes on the connection between the two stages 

 is recognized in many cases. Theoretically, therefore, the asexual stage 

 should cease to be known by its name among the Imperfect Fungi and it 

 should no longer be included in that group. Practically, however, it is 

 desirable to retain this name among the Fungi Imperfecti since it would 

 be sought there in attempts to identify it, unless the perfect stage were 

 found along with it. Thus we still seek for such genera as Aspergillus, 

 Penicillium, Sphaceloma, Ramularia, Cercospora, etc. in the manuals 

 describing the Imperfect Fungi although the perfect stages of many 

 species of these genera are known and provided with names. 



The distribution of the many thousand species of Fungi Imperfecti 

 into genera, families, and orders must necessarily be based upon vegetative 

 and asexual reproductive structures instead of upon the perfect reproduc- 

 tive stages. Inasmuch as it has been demonstrated that fungi whose per- 

 fect stages show them to be of very different families may possess rather 

 similar types of asexual reproduction it follows that genera based upon 

 the asexual reproductive forms are not necessarily assemblages of related 

 species. As an example attention may be drawn to the genus Gloeosporium. 

 In this genus the one-celled, hyaline, ellipsoidal, straight or slightly curved 

 conidia are produced, usually embedded in a gummy substance, from 

 short conidiophores packed in a palisade underneath the host epidermis 

 which is ruptured by the developing mass of conidia. This acervulus type 

 of asexual reproduction is found in some species of Gnomonia and Glom- 

 erella, both being genera in the Gnomoniaceae of the Sphaeriales. The 

 fungus commonly known as Pseudopeziza ribis Kleb., of Family Mol- 

 lisiaceae, Order Pezizales, also has a similar type of asexual reproduction. 

 A number of similar cases are known. Since, then, the genera based upon 

 asexual structures do not necessarily indicate true relationships of the 

 included species the term "form genus" was suggested for such groups by 

 Schroeter. It is in this sense that the term genus is used in this class. On 

 the other hand, as has been pointed out by several authors including 

 Petrak and Sydow (1926-1927) there is frequently a similarity in asexual 

 structures among fungi considered to be closely related as judged by their 

 perfect stage. Careful study has revealed that in many cases some of the 

 form genera of the Imperfect Fungi can be subdivided into groups of 

 species correlated with the perfect stages. Thus has come about on the 

 part of some mycologists the breaking up of the larger genera into smaller 

 more compact ones, on characters that would otherwise be considered of 

 rather minor importance except for their correlation with groups of 

 perfect fungi. 



The fact that many Imperfect Fungi possess several different spore 



