THE RUSTS OF NOVA SCOTIA. FKASER. 398 



The mycelium is perennial and thus the fungus can be 

 ^successfully combatted only by destroying the infected plants. 



PUCCINIA Pers. 



Pycnia mostly subepidermal, sub-globose or flask-shaped, 

 lioney-coloured. Pycniospores very minute, globose or ellip- 

 soid, hyaline. 



Aecia mostly with well developed peridium, at first globose 

 :and closed, at length open, usually cup-shaped or cylindrical. 

 Aeciospores arising in serial order, soon free, globose, sub- 

 globose or angular, hyaline, yellow or orange. 



Uredina generally small, sometimes paraphysate. Uredinio- 

 spores formed singly, usually with two or more germ pores, 

 rarely one. 



Telia variable in size, flattened or pulvinate, sometimes 

 paraphysate. Teliospores free, on pedicels, two-celled ( some- 

 times with one-celled spores mixed, rarely three-celled), one 

 .germ-pore in each cell. Basidiospores ovoid or reniform, 

 mostly hyaline. 



The genus Puccinia is a very large large one. Species 

 belonging to this genus can usually be recognized by the two- 

 -celled teliospcres. All the rusts that have been reported from 

 TNova Scotia with two-relied teliospores belong to this genus 

 except Gymnoconia interstitialis, the orange rust of the black- 

 " berry and raspberry. 



Sydow in his monograph describes 1231 species. He 

 includes the genera Uropyxis and Diorchidium as subgenera. 



Arthur breaks up the genus into several genera, largely on 

 the basis of the number of spore-forms present. Tranzschelia 

 and Polythelis are separated because the teliospores are borne 

 at the apex of a common stalk, and on other grounds. The 

 majority of the species now included under Puccinia he places 

 in the following four genera, which are separated by the spore- 

 "forms present as follows: 



