THE FUNGI WHICH CAUSE PLANT DISEASE 



119 



P. macrosporus Ung. 



Asci globose to elliptic, 40-80 x 35-60 /x; membrane yellowish, 

 up to 5 it* in thickness, contents colorless; spores elongate-ellipsoid, 

 2-3 xl fi. 



It produces small galls, which are at first watery looking, then 



Fig. 81. — Protomyces. A, mycelium and 

 young ascus; E, ascus with mature spores. 

 After De Bary. 



brown, upon the leaves and stems of various economic and non- 

 economic Umbelliferse. 



P. pachydermus Thiim. affects carrots and dandehons. P. 

 rhizobius Trail, grows on Poa annua in Scotland. Several other 

 species are found on wild plants. 



Subclass Protoascomycetes (p. 117) 



There is a single order, the Saccharomycetales, with about 

 seventy species. 



Mycelium often undeveloped; asci isolated or formed at different 

 points on the mycelium, mainly 4-spored; spores unicellular; 

 asexual reproduction by gemmation or by conidia. 



