Uromyces Orchidaceae. 89 



Only the teleutospores were described by Cooke, but in a portion of the 

 original material kindly supplied by Massee there were numerous uredospores 

 intermixed with the teleutospores. Sydow 2 has also found the uredospores 

 with teleutospores intermixed, on specimens of the same host-plant sent from 

 Chatham Island, New Zealand. 



If we compare the three rusts found on the Orchid genera, Microtis, 

 Chiloglottis, and Thelymitra, it is found that aecidia occur on Chiloglottisj 

 but are absent, as far as known, from the other two. The teleutospores are 

 all provided with a hyaline apiculus, but in U. microtidis the epispore is very 

 rough and knobby, and the size of the spore not generally exceeding 35 p. 

 long, while in U. thelymitrae the epispore io generally thicker, and the spore 

 polygonal and irregularly warted and altogether larger. The rust on Chtf.o- 

 ylottis generally resembles that on Microtis, but the teleutospore is larger. 



The following table will show the points of resemblance and difference in 

 the teleutospores : 



(Plate XVI., Fig. 139.) 



Chiloglottis. 



7. Uromyces orchidearum Cke. and Mass. 



Cooke and Massee, Grev. XVI., p. 74 (1888). 

 Cooke, Handb. Austr. Fung., p. 332 (1892). 

 Morrison, Viet. Nat. XL, p. 90 (1894). 

 Sacc. Syll. VII., p. 580 (1888). 



I. Aecidia hypophyllous, scattered, cup-shaped ; pseud operidial cells 



polygonal to wedge or pear-shaped, finely notched, 32-40 p. 



Aecidiospores pale yellow, subglobose to shortly elliptical, verru- 

 culose, 16-20 p. or 18-22 x 15-20 p. 



II., III. Sori mostly epiphyllous, bullate, at length erumpent, golden- 

 brown. 



II. Uredospores elliptic to ovoid, honey-yellow to golden-yellow, echinu 



late, with several germ-pores, 26-30 x 16-20 p. 



III. Teleutospores at first intermixed with uredospores, old gold colour 

 variable in shape and size, elliptic to ovoid or oblong, with pro- 

 minent hyaline apiculus (up to 9 p long), usually with irregularly 

 warted epispore, which is 3-4 p thick and brightly coloured, 

 30-51 x 19-24 p, average 36 x 21 p ; pedicel hyaline, attenuated 

 downwards, up to 77 p long. 



D 2 



