STONEWORTS 



Chara spp. and Nitella spp. 



This is an interesting family of plants represented by the most 

 common genera Chara dnidi Nitella. These plants are universally 

 recognized as being related to green algae, but technically there exists 

 a diversity of opinion by botanists as to the degree of relationship. 



These gray-green plants are more highly developed vegetatively 

 compared to most other freshwater algae. They grow submersed in 

 freshwater upon muddy or sandy bottoms, thriving best in clear, hard 

 waters. 



This family of algae is unique in that the plant body or thallus is 

 characterized by a branched erect stem that has cylindrical whorls of 

 branches at regular successions along the stem. Each stem node bears 

 these leaflike branches that give the plant the general appearance of 

 being a higher or flowering-type plant. 



Each internode (stemlike tissue between the leaf whorls) of the 

 stem consists of a single cell in Nitella , while in many species of Chara 

 the internodal cell is sheathed by a layer of vertically elongated cells 

 of much smaller diameter (insert 1). These sheathing cells give the 

 Chara stem a vertically lined appearance, while Nitella is smooth. 



These plants reproduce both vegetatively and by sexual fruiting 

 bodies. The female body or oogonium (egg-bearing case) is quite 

 conspicuous and its whorl of cap cells differ in number between genera 

 (insert 2). Both the female and male fruiting bodies are borne on the 

 leaf filaments. Vegetative propagation is accomplished by star-shaped 

 aggregates of cells that develop on the lower stem nodes, bulblet-like 

 structures on the anchoring rhizoids, or anchoring structures and 

 outgrowths from the stem nodes. 



Many species, especially those of Chara, become encrusted with 

 calcareous deposits giving the plant a harsh, rough surface. This 

 calcium carbonate accumulation around the plant may remain intact 

 after death of the plant, giving rise to the name "stonewort" or stone 

 plant. 



These plants may present problems in water distribution systems, 

 but seldom become as serious a weed pest as the filamentous green 

 algae. They rapidly become established in small pools and in standing 

 water on new irrigation systems. 



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