RHIZOCLONIUM Kuetzing 1843, p. 261 

 emend. Brand 1908, p. 69 



Filamentous, coarse and wiry, forming tangled floating mats or 

 caught about submerged aquatics; either unbranched or with short 

 rhizoidal branches, occasionally with long, multicellular branches 

 but without distinct basal-distal differentiation in the plan of branch- 

 ing. Cells stout, either short- or long-cyHndric; rarely with slightly 

 inflated lateral walls, which in most species are thick and lamellate, 

 and often completely overgrown with epiphytic diatoms and blue- 

 green algae. Chloroplast a parietal reticulum, often dense and 

 difficult of interpretation, sometimes loose and appearing as if 

 composed of many irregularly shaped ovate chloroplasts, each with 

 a pyrenoid. 



Some species of Rhizocloniiim should be compared with certain 

 expressions of Cladophora which sometimes form floating tangled 

 mats of slightly branched filaments with thick-walled cells. 



Key to the Species 



1 . Filaments frequently branched, usually very 



irregularly; branches many-celled 3 



1. Filaments seldom branched, or if so, 1-celled _ — . 2 



2. Filaments up to 80/i in diameter; walls 



as much as ISfi thick R. crassipellitum 



2. Filaments (10) -25-35- (52)^ in diameter; wall 



up to 2fi thick R. hieroglyphicum 



3. Filaments 12-22/n in diameter; branches simple R. fontanum 



3. Filaments 60-64-( 103),a in diameter; branches 



of a second order frequently present R. Hookeri 



Rhizocloniiim crassipellitum West & West 1897, p. 35. fa. 



PL 23, Fig. 1 



Filaments very coarse and wiry; unbranched; twisted and entan- 

 gled into a floating mat. Cells cylindrical or sometimes slightly 

 inflated, with thick lamellate walls; 50-70-(80)/x in diameter, 100- 

 342/x long. 



The specimens are tentatively assigned to R. crassipellitum. Plants 

 were not uncommonly found forming tangled clots about submerged 

 vegetation in hard water lakes. They are much too stout and the 

 wall too thick to agree with the larger forms of R. hieroglyphicum 

 (C. A. Ag. ) Kuetz R. crassipellitum is an African species, although 

 a variety (var. rohustum G. S. West) has been reported from the 

 West Indies. Transeau (1917) reports a form from Holland, Michi- 

 gan, which he questionably refers to R. crassipellitum. The African 

 and West Indies plants were collected on moist soil. 



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