282 CLASS ASCOMYCETEAE 



Conidia of two types: short cylindrical to filiform and ellipsoid to long 

 cylindrical. 

 Xylariaceae: stroma well developed, entirely fungal, almost always external, 

 at least eventually, and covered at first by a conidial layer. Asci long, cylin- 

 drical, ascospores one-celled, inequilaterally ellipsoid, dark brown, para- 

 physes filiform. 



To these stromatic families probably should be added: 



Phyllachoraceae (formerly included in Order Dothideales) : the members of 

 this family are leaf parasites with the stroma extending from the upper to 

 the lower surface or between cuticle and epidermis or between epidermis and 

 palisade layer. The perithecial walls are present, and true paraphyses are 

 produced. 



Family Allantosphaeriaceae. The following genera may be men- 

 tioned as they are mostly very frequent: In the Allantosphaeriaceae 

 one of the commonest genera is Diatrype with stroma effuse or isolated, 

 ectostroma deciduous, exposing a widely erumpent entostromatic disk. 

 Perithecia parallel, separately erumpent. Eight ascospores, allantoid. 

 Many species. Saprophytes or weak parasites on twigs and branches. Dia- 

 trypella is similar in many respects but the ascospores are numerous in the 

 ascus. Eidypella is much the same as Diatrype but the perithecia are 

 clustered and collectively erumpent. Anthostoma has stroma effuse or iso- 

 lated, perithecia separately or collectively erumpent. Asci, in contrast to 

 the foregoing genera, cylindrical, short-stalked, the eight ascospores in- 

 equilaterally ellipsoid and dark brown. A transitional form in ascus and 

 spore structure to the Xylariaceae, and perhaps more properly placed in 

 that family. (Fig. 91 E, F.) 



Family Diaporthaceae. In this family the genus Diaporthe with 600 

 or more species is the largest or almost so. Stroma effuse or isolated and 

 entostroma light-colored with a dark border zone. Ascospores ellipsoid or 

 fusoid, hyaline, tw^o-celled. Imperfect stage belonging to the form genus 

 Phomopsis. In the genus Valsa the stromata are isolated and the perithecia 

 clustered in the unaltered bark tissues beneath a distinct conical ecto- 

 stroma. No marginal zone. Eight ascospores, allantoid, one-celled, hy- 

 aline. Imperfect stage belonging to the form genus Cytospora. In Leuco- 

 stoma the stromata are isolated or confluent with a dark marginal zone 

 about each perithecial cluster. Asci and spores as in Valsa. Valsella 

 resembles Leucostoma but the asci are polysporous. In Endothia the 

 stromata are isolated or confluent with strongly developed, colored ento- 

 stroma. Eight ascospores, allantoid to ellipsoid, one- or two-celled. E. 

 parasitica (Murr.) And. & And. is the fungus which has destroyed nearly 

 all the trees of the American chestnut {Castanea dentata (Marsh.) Borkh.) 

 since the fungus was introduced from Eastern Asia on nursery stock 

 about 1900 or a little earlier. (Fig. 92 A-E.) 



