Cronartium. 189 



II. Uredosori hypophyllous, on yellow spots, yellowish red, minute, 



orbicular, scattered or crowded, with tubular paraphyses slightly 

 swollen towards apex, and not particularly club-shaped. 



Uredospores ellipsoid, ovoid or piriform, finely echinulate, 

 reddish orange, 4-6 germ-pores on one face, 22-29 x 16-20 /u. 



III. Teleutosori hypophyllous, minute, scattered or crowded, black, 

 readily detachable. 



Teleutospores oblong, dark-brown, warted, obtuse at the apex 

 with a colourless apiculus, 7-8 celled, with 2-3 germ-pores on one 

 face in each cell, 75-102 x 32-36 p. ; pedicel hyaline, except 

 pale-brown towards apex, expanded in the lower half, 100-150 ju 

 long and broadened up to 22 p. 



On Rosa rubiginosa L., R. canina L., and R. laxa Retz. 



Victoria Pascoe Vale, Oct., 1898 (Cronin). Ferntree Gully, 



April, 1899 (Hill). Brighton, Nov., 1901, Aug., 1903, June, 



Oct. and Dec., 1904, March, 1905, II. 

 S. Australia Third Creek Garden, Mt. Lofty Range, Nov., 1899 



(Tepper). Nov., 1900 (Agricultural Bureau), II., III. 

 Tasmania Launceston, Oct., 1902 (Littler). Hobart, Apr., 1903, 



II., III. (Rodway). 



This species is now very common around Melbourne, particularly on the 

 sweetbrier (R. rubiginosa). It has also become a pest in the nurseries, 

 causing considerable damage to the dog-rose stocks (R. canina). Seedlings 

 are attacked very severely in a favorable season and killed outright. This 

 rust occurs in some of its stages, practically all the year round, but is less 

 common in midsummer. The uredospores resemble the caeomospores in their 

 size and shape, but may be distinguished by their long stalks (up to 56 /<) 

 and their germ-pores. 



The mycelium of the caeorna may winter in the stems, so that by means 

 of cuttings the disease was probably introduced into Australia. It may 

 also have been introduced with the seeds of the sweetbrier, for that was 

 among the first European plants to be imported into Tasmania and New 

 South Wales, and used as hedges. 



(Plate XXVI., Figs. 229-233 ; Plate L, Fig., 37.) 



CRONARTIUM Fries. 



Only one species of this genus is known here, and it occurs rather com- 

 monly on certain leguminous plants. So far teleutospores only have been 

 found. This genus produces uredo and teleutospores on one host plant, 

 and the aecidial stage on another, but the latter has not yet been 

 found in Australia. In Europe there is a bladder-rust on the bark of JPMMM 

 sylvestris, and this has been proved to be the aecidial stage of Cronart 

 asclepiadeum (Willd.) Fr. As in so many other similar cases, this stage wu> 

 considered to be an independent form, and named Peridermium cornui 

 Rostr. and Kleb. 



General characters. Sperm ogonia truncate to conoid. 



Aecidia with bladder-like, irregularly opening pseudoperidia (Pet^ider- 

 mium). 



Aecidiospores without germ-pores, separated by distinct intermediate 

 cells, epispore always more or less regularly warty reticulated. 



Uredo-layer included in hemispherical pseudoperidum, which opens at apex 

 by a narrow pore. 



