Vol. XIV, No. 8 —Botanical Gazette -Aug., i889. 



Notes on Fungi. I. 



W. G. FARLOW. 



Peronosp 



335), the statement was made that the Cystopus parasitic on 

 ConvolvulacecB in the United States was apparently the same 

 as the sEcidtum Ipomcece-pandurance of Schweinitz, Syn. 

 .Fung. Car. Sup. no. 454, and a doubt was expressed as to 

 whether it should be united with the C. cubicus (Strauss) Lev. 

 which infests Composite, although the conidia of the two 

 forms are much alike. At that date the oospores of the form 

 on Convolvulacece had not been seen, and I suggested that 

 they should be sought in the stems and petioles rather than 

 in the leaves. In the autumn of 1888 I received from Prof. 

 L. H. Pammel some very interesting specimens of swollen 

 stems of Ipomcea pandurata, collected at Valley Park, near St. 

 Louis, Mo., in which he had found the oospores in abundance, 

 while the accompanying leaves were covered with conidia. 

 The swellings of the stems were very striking, and in one 

 fine specimen the tumor formed by the hypertrophied paren- 

 chyma of one side of the stem was six inches long and some- 

 what over an inch in diameter, while the stem itself, whose 

 diameter was not greater than a quarter of an inch, was bent 

 over in the form of a horse-shoe by the growth of the unilat- 

 eral tumor. The surface of the tumors when fresh was con- 

 tinuous, but in diving they cracked open and the inner portion 

 was exposed in numerous places. Microscopic examination 

 showed that the oogonia were different from those of any 

 other Cystopus known to me, since their walls were not 

 smooth, but raised in blunt papillae, or short flexuous ridges 

 over their whole surface. In the younger oospores the 

 smooth-walled antheridia were in marked contrast with the 

 papillate oospores, and the pollinodia were larger and more 

 prominent than in other Peronosporea, so that the present 

 species is remarkably well adapted for the study of the fer- 

 tilization in this order. The oogonia are very irregular in 

 shape, appearing in some sections nearly triangular, and 

 their average diameter is 45^. The oospores are on an aver- 

 age about 36,* in diameter, with an endospore 30 thick. The 



