THE GREEN AI<GAE OF NORTH AMERICA 279 



KEY TO THE SPECIES OF ENDODERMA. 



i. Endophytic, marine. 2. 



i. Epiphytic, fresh water. 4. 



2. In leaves of Zostera. 3. E. perforans. 



2. In marine algae. 3. 



3. Cells averaging 9 ,u diam., cylindrical, i. E. Wittrockii. 



3. Cells averaging 6 ,u diam., irregular. 2. E.viride. 



4. Cells subglobose to ellipsoid. 4. E. Pithophorae. 



4. Cells much flattened. 5. E. polyinorp hunt. 



1. E. WITTROCKII (Wille) Lagerheim, 1883, p. 75 ; Hazen, 

 1902, p. 226, PI. XLII, fig. i ; P. B.-A., Nos. 265, 1469. Fila- 

 ments simple or irregularly branched, with tapering ends ; 

 branches sometimes united laterally ; cells cylindrical, 5-10 /x, 

 usually 9 //.diam., i-i}4 diam. long, with one pyrenoid ; growing 

 in the cell walls of brown, less commonly of red algae ; repro- 

 duction little known. Fig. 100. Me. to Conn. Europe. 



Probably common in summer and autumn, but easily over- 

 looked, as there is seldom anything in the appearance of the 

 host to indicate the presence of the endophyte. It has been 

 found most frequently in Elachista furicola, but occurs in other 

 algae ; at times it is quite common in Desmotrichum undulation . 



2. E. VIRIDE (Reinke) Lagerheim, 1883, p. 74 ; Entocladia 

 vindis Reinke, 1879, p. 476, PI. VI. Filaments usually much 

 branched, 3-8 /A, usually 6 //. diam., cells 1-6 diam. long, some- 

 times cylindrical, oftener irregularly swollen and contorted, with 

 one pyrenoid ; terminal cell blunt or tapering ; growing in cell 

 walls of various algae. Mass. Europe. 



A smaller plant than the preceding, and with more irregular 

 branching. In Europe it has a more southern range than E. 

 Wittrockii, and it .is to be expected in localities south of Cape 

 Cod. 



3. E. PERFORANS Huber, 1892, p. 316, PI. XIV. Filaments 

 3-5 p. diam., endophytic in the dead leaves of Zostera marina ; 

 cells more or less irregular in form and of varying length, with 

 one pyrenoid ; larger, rounded cells formed here and there, up 

 to 14 p. diam; asexual reproduction by ovoid or subspherical 

 4-ciliate zoospores with stigma, formed in the larger cells, 8 in 

 a cell. Me., Mass. Europe. 



The slender filaments creep among the epidermis cells of the 

 host, while the larger cells and sporangia are formed within the 

 large cells of the inner layer of the Zostera. The zoospore 

 comes to rest on the surface of a Zostera leaf and emits a tube 



