LEPTO MIT ALES 895 



deliquescence of the apical papilla, generally surrounded by an evanes- 

 cent vesicle ; antheridium single, androgynous, monoclinous or diclinous ; 

 oogonia borne like the zoosporangia; oospore borne singly and loosely 

 in the oogonium, thick-walled, areolate or stellate, germination not 

 observed. 



The plants form white gummy pustules, primarily on twigs and 

 rosaceous fruits. 



The habit of the thallus even in a single species is extremely variable 

 and identification of the species is impossible unless the sex organs are 

 present. One species (Rhipidium parthenosporum) forms thin-walled 

 parthenospores rather than oospores. 



Liitjeharms (1937) has presented the arguments for conserving 

 "Rhipidium'"' against several earlier homonyms. 



KEY TO THE SPECIES OF RHIPIDIUM 



Antheridium present; oospore stellate, not filling the oogonium 

 Antheridium diclinous, monoecious, or dioecious 



Antheridium applied at the base of the oogonium R. interruptum. p. 895 

 Antheridium applied at the apex of the oogonium. .R. thaxteri, p. 898 



Antheridium androgynous R. americanum, p. 899 



Antheridium lacking, parthenospore smooth-contoured, filling the 



oogonium R. parthenosporum, p. 900 



Rhipidium interruptum Cornu 



Bull. Soc. Bot. France, 18:58. 1871; van Tieghem, Traite de Botanique, 



p. 1024, fig. 617. 1884. Paris 



(Fig. 71 E, p. 894) 



Rhipidium continuum Cornu, Bull. Soc. Bot. France, 18: 58. 1871. 



Rhipidium europaeum Minden, Kryptogamenfl. Mark Brandenburg, 5: 597, 

 fig. 9 (p. 590). 1912 (1915); Falck, Mykolog. Untersuch. Berichte, 2 (2) : 

 187, figs. 3, 5-14, pi. 2, figs. 12-19. 1916. 



Rhipidium europaeum var. interruptum Minden, in Falck, Mykolog. Unter- 

 such. Berichte, 2: 172. 1916. 



Rhipidium europaeum var. compaction Forbes, Trans. Brit. Mycol. Soc, 

 19:234, pi. 10, fig. 11. 1935. 



Basal cell with or without a cylindrical axis, 400-900 y. long by 30-90 u. 

 in diameter, the platform extremely variable in size and shape, either 



