Chara

Chara (Class Chlorophyceae, Order Charales), popularly called 'stonewort', is a submerged freshwater alga anchored in the mud of lakes and slow streams (C. baltica tolerates saline water); its thallus is often gritty to the touch because it is encrusted with calcium and magnesium carbonate.

The multicellular, macroscopic plant body is differentiated into a branched main axis and thread-like, multicellular rhizoids (recognisable by their oblique cross-walls) that anchor the plant and absorb salts and solutes. The main axis alternates nodes and internodes: each internode is a single elongated internodal (axial) cell surrounded by smaller, vertically elongated cortical cells that arise from the node (cortical cells are absent in C. wallichii and C. corallina). Three kinds of appendages arise at each node — branches of limited growth, branches of unlimited growth, and stipuloids — and growth of the main axis and its branches is driven by an apical cell. Nodal cells are uninucleate with a few ellipsoidal chloroplasts, while internodal cells are larger, multinucleate, and packed with numerous discoid chloroplasts; the cytoplasm itself is layered into an outer ectoplasm and an inner, actively streaming endoplasm. …