222 COMPARATIVE MORPHOLOGY OF FUNGI 



The simple species of Leptosphaeria correspond in structure of con- 

 ceptacles and perithecia to Pleospora, and since Pleospora still is counted 

 in the Sphaeriales, they were placed in the same family with it. In a few 

 of them, as in L. doliolum, on the roots of the larger weeds, especially 

 Urtica and Angelica, the conceptacles, as in Pleospora, are still closed 

 in youth. They do not open by the crumbling of the papilla, however, 

 but by partial slimy resorption of the lid tissue whereby at maturity 

 a typical pore results. In both Pleospora and the L. doliolum group, 

 the paraphysoids are long-celled filaments and, when mature, almost 

 indistinguishable from typical paraphyses. In Leptosphaeria acuta on 

 Urtica dioica and L. herpotrichoides causing the increased fragility of 

 stalk in young shoots of rye, a typical ostiole pierced by a canal is formed 

 organically in the course of development, as in the true Sphaeriales; fur- 

 thermore, the species of this group, like the true Sphaeriales, have true par- 

 aphyses formed by subsequent growth of the hyphae of the ground tissue. 



While Leptosphaeria doliolum and L. acuta mark the beginning and 

 end of a series which leads from true Pseudosphaeriaceae to true Sphaeri- 

 ales (i.e., the forms among these with discreet perithecia) a special 

 branch of the Leptosphaeria group connects directly to Botryosphaeria 

 and leads thence to the stromatic Sphaeriales and Dothideales. Not only 

 do these genera merge in the vertical direction, but also horizontally and 

 laterally. Hence it is difficult to decide whether this stromatic branch 

 of the Leptosphaeria group (in the developmental scheme on p. 223 

 imagined as the left wing of Leptosphaeria) should be joined with forms 

 having discrete fructifications which appear to be perithecia and show 

 no traces of stromata, or whether they would not be better placed in a 

 special genus of the Dothioraceae beside Botryosphaeria or, as Hoehnel 

 (1918) wishes, shifted to the Dothideales. 



This left wing connects directly to the solitary species, through 

 forms whose perithecia are gregarious only under favorable conditions 

 of nourishment. In the higher forms as in Leptosphaeria caespitosa on 

 the dry roots of Artemisia campestris, or L. salebrosa on decaying cabbage 

 stumps, the perithecia appear evenly on a basal stroma which is often 

 only weakly developed. If the basal stroma is more strongly developed 

 and the conceptacles are caespitose, the mat ruptures during the epidermal 

 development, i.e., before the conceptacles are externally visible, and the 

 fungus attains instantaneously an entirely different appearance, sugges- 

 tive of the higher species of Botryosphaeria and Chevalier opsis. If one 

 imagines this basal stroma more strongly developed, one has Rosenscheldia 

 which, according to present systematic classification, is placed in the 

 Dothideales. Thus L. doliolum and L. acuta form the beginning and end 

 members of the Pseudosphaeriaceae-Sphaeriales series and L. caespitosa 

 and Rosenscheldia two stages in the line of development from the Pseudo- 

 sphaeriaceae to the Dothideales. 



