ORDER AURICULARIALES 441 



basidium) becoming separated by a septum from the short cylindrical 

 thin-walled hypobasidium which is not enlarged as in some genera. The 

 epibasidia are transversely three septate and from each cell is produced a 

 long tube at whose apex a sterigmatic structure is formed on which arises 

 the one-celled uninucleate basidiospore. This fungus is found on many 

 species of mosses in Europe and America. (Fig. 144 A.) 



Jola is also parasitic upon mosses but mostly in the sporophytes. It 

 seems to be almost exclusively tropical. It forms its small spherical or 

 elongated spore fruit at the apex of the sporophyte. It appears to be more 

 or less gelatinous. The binucleate hyphal cells at the surface enlarge at the 

 ends and in these terminal cells (hypobasidia) the nuclei unite. From the 

 apex of each emerges the epibasidium within which the meiotic division 

 of the nucleus takes place. After the three transverse septa have been 

 formed short or long tube-like hyphal growths reach the surface of the 

 hymenium and bear the uninucleate spores at their tips. Below the ter- 

 minal basidium the next cell grows out sympodially and produces another 

 basidium and this process is repeated until a dozen or more basidia are 

 produced (see Gaumann, 1922). Closely related, but growing on fungi 

 instead of mosses is the likewise tropical genus Cystobasidium. (Fig. 

 144 B.) 



Herpobasidium filicimim (Rostr.) Lind was studied by Jackson (1935). 

 It is parasitic upon the leaves of ferns in which the mycelium is inter- 

 cellular, producing massive coiled haustoria in the cells of the host. The 

 internal mycelium emerges through the stomata, forming small white 

 patches. On the surface the basidia arise as terminal cells of upright hy- 

 phae. They are usually slightly bent. No distinction of hypobasidium and 

 epibasidium is observable. The fusion nucleus divides once, by the first step 

 of meiosis, so that the two nuclei now have the haploid number of chromo- 

 somes. A single septum is formed and one basidiospore develops on the 

 tip of a sterigma on each cell. The spore is uninucleate and no nuclear 

 division has been observed. It may germinate by repetition. The origin of 

 the dicaryon phase is unknown as is also the case in the two foregoing 

 genera. No clamp connections have been observed. This species occurs in 

 Europe and North America. 



Another genus, Platycarpa (Couch, 1949), is parasitic upon tropical 

 ferns. The fruit body is resupinate, very small, dry to subcartilaginous, 

 separable from the host at maturity. The vegetative mycelium forms 

 coiled haustoria within the epidermal and mesophyll cells or in the sporog- 

 enous cells of the host. No clamp connections have been observed. Exter- 

 nally a more or less felty mass of hyphae occurs. These are more or less 

 wavy or loosely coiled near the surface and produce terminally on short 

 branches the ovoid probasidia. These are hyaline-walled and germinate 

 by the production of a straight or, more often, curved and mostly four- 



