322 COMPARATIVE MORPHOLOGY OF FUNGI 



the apothecia are formed in the interior of the leaves as brown hyphal 

 tangles and break forth during early spring rains. They have a brown 

 peridial layer, 2 to 3 cells thick, which elongates below like a stipe and 

 opens above like a cup. 



A similar life cycle has been determined for Pseudopeziza Medicaginis, 

 causing a leaf spot of alfalfa, for P. Trifolii on clover, forming apothecia 

 even on the living leaves, for P. tracheiphila the cause of red burn of the 

 vine and for Fabraea (differing from Pseudopeziza by multi- rather than 

 unicellular ascospores), e.g., F. maculata (Entomopeziza Soraueri, E. 

 Mespili), the cause of a disease of leaves and fruits of many fruit trees 

 (conidial form Entomosporium Mespili), and F. Fragariae, the cause of 

 strawberry leaf spot (conidial form Marssonina Fragariae). 



In other forms, in addition to free conidiophores, pycnia are known, 

 as in Pezizella Lythri (Shear and B. 0. Dodge, 1921) which causes an 

 early rot of strawberries and other fruits and exits in pathological litera- 

 ture under 27 synonyms : the acervuli as Hainesia Lythri, Sphaeronema 

 corneum and Patellinia Fragariae, etc., the pycnial form as Sclerotiopsis 

 concava, Leptothyrium macrothecium, Sporonema quercicolum, etc. 



Only Fabraea Ranunculi, on Ranunculus cassubicus whose young 

 apothecia form a group of ascogonia with long multicellular trichogynes, 

 has been studied cytologically. Antheridia are lacking (Guseva, 1923). 

 Here are relationships similar to those we shall follow in detail in the 

 operculate forms. 



Helotiaceae. — This family, as that of the Epichloe-Claviceps series of 

 the Hypocreales, includes two different groups of forms, one (probably 

 simpler) without sclerotia and one (probably higher) with sclerotia. 

 Unfortunately no intermediate forms are known between these two 

 extremes. 



Of the stage without sclerotia, may be mentioned Dasycypha caly- 

 cina (D. Willkommii), the cause of larch canker. The mycelium of the 

 fungus grows through the bark as a wound parasite and stimulates the 

 cambium to cankerous growths. After the death of the bark these erupt 

 as small, yellowish-white pustules which, in tortuous cavities of their 

 surfaces, form small unicellular hyaline conidia. On the same spot (and 

 also on fallen branches) there later arise orange-colored apothecia. 



Sclerotinia is divided into two subgenera, Stromatinia, which develops 

 sclerotia in mummified fruit, and Eusclerotinia which develops them in 

 root stems or leaves. In the former, the shape of the sclerotia is deter- 

 mined by that of the fruits, in the latter the sclerotia occur in regular 

 weals or callosities. 



The more important representatives of the first subgenus are parasitic 

 on fruits of Ericaceae and Rosaceae, e.g., Sclerotinia Urnula (S. Vaccinii) 

 on Vaccinium Vitis-idaea, S. Ledi (S. heteroica) on Ledum palustre and 

 V. uliginosum, S. baccarum on V. Myrtillus, S. Padi on Prunus Padus, 



