Pucdnia Acanthaceae. 141 



X. Mesospores, occasional, similarly coloured, nearly globose, very 

 slightly roughened, 20 p diam. 



On leaves of Mentha laxiflora Benth. 



Victoria near Melton (Reader). 



On leaves of Mentha pulegium L. 



Victoria Myrniong, Aug., 1904, II., III. (Brittlebank). 

 The teleutospores are prominently warted. 



(Plate XXIX., Fig. 250.) 



ACANTHACEAE. 



Ruellia. 



65. Puccinia mussoni McAlp. 



Sori amphigenous, minute, usually rounded, bullate, scattered or some- 

 times in groups. 



II. Uredospores yellow with thick, chestnut wall, globose to shortly 



ellipsoid, strongly echinulate, with two germ-pores on one face, 

 30-38 /* diam., or 28-34 x 18-23 p. 



III. Teleutospores intermixed with uredospores, dark chestnut-brown, 

 oblong, with thickened wall and roughened surface, sometimes 

 slightly constricted, rounded at both ends, not thickened at apex, 

 36-46 x 28-36 p; upper cell resembling lower, but usually a little 

 larger ; pedicel generally lateral and even sometimes on a level 

 with the septum, flexuous, hyaline, up to 60 p long and 7 p 

 broad. 



On living leaves of Ruellia australis Cav. 



New South Wales Richmond River, June, 1896 (Musson). 



The teleutospores were not very plentiful in the specimens examined, but 

 the sori containing them could be detected by their darker brown colour. 

 The lateral pedicel to the teleutospore naturally suggests P. lateripes B. and 

 Rav., but a closer inspection reveals important difterences in the two kinds 

 of spores. 



I have compared the Australian species with specimens on the leaves of 

 R. strepens L. from N. America in Sydow's Ured. Exs., No. 1374, and 

 Kellerman's Ohio Fungi, No. 130, and it is evident that we are dealing with 

 similarity of type due to the affinity of the host-plants, with considerable 

 divergence in the character of the spores. Unfortunately, P. lateripes B. 

 and Rav. and P. ruelliae (B. and Br.) Lagh. are confounded, for although 

 Sydow labels his specimen as the former, in his Monograph he names it 

 the latter. In this specimen the finely echinulate uredospores are ellipsoid 

 to ovate, and measure 24-28 x 19-21 /*, while here they are larger. The 

 teleutospores likewise only measure 29-34 x 18-22 p, and are very strongly 

 warted. 



This species differs from P. longiana Syd., in the larger uredospores and 

 the teleutospores not being thickened at apex, and from P. lateripes and 

 P. ruelliae in the larger size of uredo- and teleuto-spores. 



(Plate V., Figs. 43, 44.) 



