178 



THE FUNGI WHICH CAUSE PLANT DISEASE 



species belonging to eighty-nine genera; one hundred forty-six 

 more hosts, some doubtful, are reported. Among the economic 

 host genera are Adonis, Alyssum, Anemone, Aquilegia, Brassica, 

 Calendula, Catalpa, Clematis, Cucumis (?), Cucurbita (?), Dahlia, 

 Daucus, Delphinium, Diervilla, Dipsacus, Fagopyrum, Lupinus, 

 Lycopersicum, Medicago, Paeonia, Phaseolus, Pisum, Tragopogon, 

 Trifolium, Verbena, Vicia, Scabiosa, Symphytum, Valeriana. 



This is the most variable species of this genus varying widely 

 in its every character. It includes several species which have by 



some been set aside as distinct, e. g., 

 E. martii, E. umbelliferarum and 

 E. liriodendri. 



Salmon ^ found that the conidia 

 of this form grown on Trifolium 

 pratense were unable to infect other 

 species of Trifolium. 

 E. cichoracearum D. C.^ 

 Amphigenous; mycelium usually 

 evanescent, rarely persistent, white 

 or sometimes pink; perithecia gre- 

 garious or scattered, 80-140 or 

 rarely 180 /x; cells variable, often 

 very distinct, 10-20 fi; appendages 

 variable in nxmiber and size, some 

 shade of brown; asci usually nu- 

 merous, about 10-15, but varying 

 from 4 to 36, variable in size and shape, narrowly ovate or 

 subcylindric to broadly-ovate, more or less stalked, 58-90 x 

 30-35 fi; spores 2, rarely 3, 20-28 x 12-20 n. 



Conidiophores (=Oidium ambrosiae ThOm), short; conidia 

 minute, elliptic, white, 4-5 x 7-5.3 fi. The species is quite vari- 

 able sometimes closely approaching E. polygoni. 



Cosmopolitan. The hosts are very numerous, among them 

 being: Borago, Calendula, Centaurea, Cichorium, Clematis, 

 Cucurbita, Dahlia, Helianthus, Humulus, Mentha, Nicotiana, 

 Phlox, Tragopogon, Valeriana, Verbena, Symphytum. It is of 

 especial import on composites and cucurbits. 

 Reed ^ has made very extensive culture studies of this species 



Fig. 



^00 



128. — E. cichoracearum, asci 

 and spores. After Salmon. 



