I 22 UROMYCES 



( )ii Allium Schoenoprasum, A. Scorodoprasum, and (ac- 

 cording to Sydow) A . .$])haerocephalum. Not common. ( Fig. 73.) 



It cannot be considered as certain thai this is a species distinct from 

 Puccinia Porri Wint., but as it presents slight differences, it is better, in 



the total absence of culture experiments, to keep it separate for the time. 

 The difficulty lies in the fact that the teleutospores of this Uromyces agree 

 I lerfectly with the mesospores of the Puccinia (except perhaps in the greater 

 variability of the latter) ; but the teleuto-sori of the Uromyces are generally 

 larger and more persistently covered by the epidermis, and one searches 

 in vain in them for two-celled spores, such as are found freely in the sori 

 of the Puccinia. Fischer says that the uredospores of P. Porri have only 

 three germ-pores. According to Sydow, the Uromyces occurs only on the 

 three species of Allium mentioned above and A. rotunda m, while the 

 Puccinia is found on them as well as on many other species of the genus. 

 Nevertheless the two forms are closely allied and from the evolutionary 

 point of view the Uromyces must be regarded as a specialised state or 

 mutation of the Puccinia. Neither of them has an secidial stage. 



Distribution : Central and North-Western Europe. 



34. Uromyces Colchici Massee. 



U. Colchici Mass. Grevillea, xxi. 6, pi. 182, f. 16 — 18 ; Diseases of 

 Cult. Plants, p. 292, f. 85 ; Text-book of Plant Diseases, p. 227, 

 f. 56. Sydow, Monogr. ii. 268. 



Teleutospores. Sori amphigenous, scattered, rather large, 

 elliptical, sometimes circinating, up to 2 mm. long, 

 covered for some time by the epidermis which at 

 length splits, then sub-pulverulent, brown ; spores 

 subglobose to ovate, rounded above, with a broad 

 flat hyaline papilla, smooth, pale-brown, 28 — 40 x 

 Fig. 74. u. 20 — 28 /x ; epispore 3 — 3^ /j, thick ; pedicels hya- 



Colchici. i me rather long, but very deciduous. 

 Teleutospore, ' S ' J . . 



from the ori- On leaves oi Lolcf ncum speciosum. Kew 



speci- Gardens ; unknown in the world elsewhere. 



mem J 



II 11*11 . 



(Fig. 74.) 



The teleutospores remain on the dead leaves and germinate in the 

 following spring, so that if Colchicum is again planted in the same ground 

 or allowed to remain there, it is liable to contract the disease year after 

 year. As in all similar cases, the best preventive against future attacks 



