THE FUNGI WHICH CAUSE PLANT DISEASE 345 



M. sazifragarum (D. C.) Schr. 

 I and III on Saxifrages. 



Physopella Arthur (p. 340) 



Cycle of development imperfectly known; only uredinia and 

 telia recognized, both subepidermal. Uredinia erumpent, definite, 

 roundish, pulverulent, encircled by more or less clavate paraphyses 

 which are often united at their bases, or wholly, into a pseudo- 

 peridium opening by a central pore. Urediniospores borne singly 

 on pedicels, obovate-globoid or ellipsoid; wall pale-yellow, echinu- 

 late or rarely verrucose, pores obscure. Telia indehiscent, form- 

 ing lenticular masses, two or more cells thick at center. Telio- 

 spores 1-celled; walls smooth. 



P. vitis (Thiim.) Arth." 



II. Uredinia hypophyllous, scattered thickly over wide areas, 

 round, minute, 0.1 mm. or less across, soon naked, arising between 

 epidermis and mesophyll, surrounded by numerous incurved pa- 

 raphyses, pulverulent, pale-yellow, fading to dirty white, ruptured 

 epidermis inconspicuous; urediniospores broadly ellipsoid or obo- 

 vate, 13-17 by 18-27 /*; wall nearly colorless, thin, 1 n, minutely 

 and rather closely echinulate, pores obscure; paraphyses hyphoid, 

 curved and irregular, 6-10 m thick, 30-60 m long, wall uniformly 

 thin, 1 11, yellowish. 



III. Telia hypophyllous, scattered thickly over large areas, 

 roundish, minute; 0.1-0.2 mm. across, indehiscent, 3 to 4-cells 

 thick; teliospores ovoid, 12-15 by 20-30 y., wall smooth, nearly 

 colorless, thin, 1 m or less. 



On grape leaves in Southern United States and West Indies. 

 Also in South America and Japan. 



P. fici (Cast.) Arth." 



II. Uredinia hypophyllous, scattered thickly over large areas, 

 roundish, usually small, 0.1-0.3 mm. across, or rarely larger, buUate, 

 arising between epidermis and mesophyll, tardily dehiscent by cen- 

 tral rupture, encircled by delicate, evanescent paraphyses, pulveru- 

 lent, pale cinnamon-brown, ruptured epidermis overarching or 

 erect; spores obovate-globoid, 14-20 by 18-27 m; wall pale-yellow, 

 thin, 1-1.5 /i, sharply and rather sparsely echinulate, pores ob- 



