densely packed, vertical filaments that terminate in enlarged cells, 

 which may form akinetes or serve as sporangia. Cells cylindrical, 

 or with convex lateral walls; 15-30/x. in diameter, 35-60/a long. Cell 

 walls becoming thick and lamellate. 

 On shells. Mich., Wis. 



Gongrosira lacustris Brand 1907, p. 502 



Growing on wood and stones, forming rather delicate fronds of 

 horizontally growing and downward-projecting branches (which 

 penetrate the substiate when on wood), as well as erect branches 

 with cells about the same size as those in the prostrate filaments. 

 Cells both short- and long-cylindric, 6-14/x in diameter. 



Mich. 



TRENTEPOHLIA Martins 1817, p. 351 

 An irregularly branched filament with a prostrate portion from 

 which erect branches arise, forming velvety or cushion-like expan- 

 sions on moist soil, rocks, logs, and tree trunks; brick- or rusty-red 

 because of an abundance of haematochrome, which often completely 

 masks the chlorophyll. Cells cylindrical or slightly swollen, the walls 

 frequently thickened and roughened externally. Chloroplast a 

 parietal band, usually breaking into irregularly shaped discs, without 

 pyrenoids (the form of the chloroplast often masked by the density 

 of the cell contents and by the red pigment). Branches but very 

 little less in diameter than the main axis and slightly tapering toward 

 the apical region. Terminal cell bluntly rounded at the apex, in some 

 species having a cap of pectose material. Asexual reproduction by 

 means of biflagellate swarmers, formed several to many within 

 globose or ovate sporangia borne on lateral or terminal, hooked or 

 recurved cells; sexual reproduction by isogametes produced in some- 

 what modified vegetative cells, terminal or intercalary. 



Species of this genus frequently enter into association with fungi 

 to form the lichen Coenogonium. 



Key to the Species 



Cells cylindrical, 11-20-(30)m in diameter-— T. aurea 



Cells slightly swollen, lateral walls convex, 



up to 35m in diameter T. lolithus 



Trentepohlia aurea (L. ) Martius 1817, p. 351 



PI. 67, Figs. 6-9 



Plants rusty-brown or golden-colored, sometimes yellow in shaded 



areas. Filaments branching variously according to habitat, sometimes 



sparingly, sometimes repeatedly branched. Cells somewhat inflated 



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