466 PUCCINI A ON GROUNDSEL, 



Link, should be raised to specific rank. The Puccinias which he 

 enumerates as occurring on Senecio are : — P. conglomc.raia, P. 

 senecionis, P. expansa and /'. uralensi)*; P. tranzsr.hdU is also 

 given, but it is now regarded as a variety of P. cou'/lornerata. In 

 P. urahjisis'^ the sori are hypophyllous, the teleutospores are much 

 shorter (36-43 /x), and no aecidiospores are known, so that the 

 distinctness of this species is still maintained. When the proper 

 season comes round, infection experiments will ]^e carried out 

 mutually on Senecio vulgaris and Erechf.ites qva-Irvieutata. 



Trimorphic Teleutospores, 



There are three forms of teleutospores in this species, as 

 already stated — normal or uniseptate, aseptate and biseptate. 



A similar case was recorded by W. B. Grovef in Pucciuia 

 betonicce, DC, belonging also to the Pucciidopsin, in which he 

 found one-celled, two-celled and three-celled teleutospores. Since 

 then several similar cases have been ]:)rouglit to light, and e^'en 

 four-celled spores have been observed in Fuccinia (jramiuin, Pers. 

 In Pucciuia saccardoij Ludw., an Australian species on Goodnuia 

 gp/niculata, Dr. Ludwigj records the occurrence, among the 

 normal teleutospores, of unicellular and tricellular spores, some- 

 times of enormous size, and occasionally singular horn-like 

 ])ranching spores, resembling those of PJiva inddium ohtusiim. 

 The w^hole subject is very fully and sMy discussed by Dr. P. 

 Dietel in his paper on " Beitrage zur Morphologie und Biologie 

 des Uredineen."i^ The one-celled spores are commonly known as 

 mesospores, and various views are held as to their meaning. 

 Winter! I regards them simply as unicellular teleutospores and 

 Sorauerll considers them as transition forms between uredospores 



* Zeitsch. f. Pflanzk. Vol. ii. Pt. 2, 104 (1892). 



t Gardener's Chronicle, Vol. xxiv. p. 180 (1885). 



+ Hedw. xxviii. pp. 362, 303 (1890). 



§ Hot. Centralb. Vol. xxxii. (1887). 



il Die Pilze, Vol. i. p. 133 (1884). 



H Pflanzenkrk. Vol. ii. p. 213 (1880). 



