106 



THE LOWER FUNGI— PHYCOMYCETES 



phlyctis embraces those which cause pronounced deformation or 

 gall formation. Correlated with this distinction there is a sUght 

 difference in the shape of the resting spore, that of Urophlyctis 

 being more often and more strikingly flattened on one side. This 

 separation is clearly inadequate and further investigation of 

 these forms will probably result either in the fusion of the two 

 genera or in a rearrangement of the species on a wholly new and 

 as yet unsuspected basis. 



Fig. 38. — (a) Urophlyctis leproides (Trabut) P. Magnus forming galls on beet 

 root; (b) U. kriegeriana Magnus, showing section through gall on Carum con- 

 taining sorus of resting spores; (c) U. pulposa (Wallroth) Schroter, showing 

 resting spores in cells of Chenopodium. (a, b, after Magnus; c, after Schroter 

 1897.) 



The genus Physoderma as here constituted contains about 

 twenty species, of which the following are known to occur in 

 North America. 



P. macular e Wallr. — in Alisma plnntago. 



P. menyanthis de Bary — in Menyanthis trifoliata. 



P. zeae-maydis Shaw — in Zea mays (see Mycologia, 14: 81, 1922). 



P. vagans Schroter — in Sium, etc. 



P. heleocharidis Schroter— in Eleocharis. 



