1) Agar 2) Alga 1) Chlorophyte 2) Green algae 
• (n.) Any plant of the genus Chara; -- so called because they are often incrusted with carbonate of lime. See Chara.
any of certain green algae of the class Charophyceae. Most stoneworts generally occur in fresh water. Some are calcified (Chara) and may accumulate ...
Stone'wort` noun (Botany) Any plant of the genus Chara; -- so called because they are often incrusted with carbonate of lime. See Chara . 
[n] - any of various submerged aquatic algae of the genus Chara having nodes with whorled filamentlike branches
noun any of various submerged aquatic algae of the genus Chara having nodes with whorled filamentlike branches; usually encrusted with calcium carbonate deposits
any of a plantlike group of green algae constituting the class Charophyceae, having a jointed body frequently encrusted with lime and usually attached to the bottom in fresh water.