132 



PUCCINI \ 



Pig. 83. P. Chry- 

 santhemi. Ure- 

 dospore (Brit- 

 ish). 



Uredospores. Sori generally hypophyllous, on irregular 

 pallid-yellow or brownish spots, scattered or in 

 clusters, about 1—1! nun. diam. often circi- 

 oate, pulverulent, snuff-brown; spores globose 

 to ellipsoid, delicately echinulate, brown, 24 — 

 •">2 x 17 — 27 p, mostly with three germ-pores. 



[Teleutospores. Mixed with the undospores, 

 oblong or ellipsoid, rounded and slightly 

 thickened above, usually rounded or some- 

 what tapering at base, scarcely constricted, 

 delicately verruculose, chestnut-brown, 35 — 57 x 20 — 25 fi : 

 pedicels thick, hyaline, persistent, 35 — 60 [i long; mesospores 



subglobose or pyriform, slightly 

 thickened at the summit, 32 — 37 x 

 20—21 fi.] 



On leaves of Chrysanthemum in- 

 dicum and C. sinense (not on other 

 species of the genus, much less on 

 other genera of Compositae), in 

 greenhouses, all the year round. The 

 leaves that are attacked soon flag and 

 die. (Figs. 83, 84.) 



This species is said to be very common 

 in Japan. It was first observed in England 

 in 1895, and has been found in other Euro- 

 pean countries and in North America ; in 

 1904 it reached Australia and New Zealand. 

 In Japan it produces teleutospores in 

 separate sori, which are hypophyllous, 

 roundish, dark-brown and naked, but in 

 Europe the teleutospores have been rarely 

 seen, though mesospores occasionally occur. 

 Abnormal and 2-celled uredospores (as well 

 as 3- or 4-celled teleutospores) have been 

 described and figured by Roze, Jacky and Eischer ; but these I have not 

 seen in British specimens. 



Since, under the conditions in which the plants are grown here, the 

 young shoots appear above ground before the old ones die away, it is 

 probable that the parasite maintains itself by the uredospores alone ; the 

 alternative would be the possession of a perennial mycelium, which has not 



Fig. 84. P. Chry santhemi. 



Teleutospores and uredo- 

 spores, one abnormal (after 

 Fischer). 



