The large cells of the Characeae have served for many decades as the model system par excellence to study basic physiological and cell biological phenomena in plants. One reason for this model character was given by the many physiological and structural similarities between these highly evolved green algae and higher plants. More important for the model character, however, was the unique geometry of the internodal cells. Single Chara cells can be as long as 10 cm with a diameter of 1 mm. These dimensions favoured the first use of intracellular microelectrodes in plants. Later, they basically imposed no limits to experimenters using even multiple microelectrodes simultaneously in one cell. The geometry of the cells also provided an invitation to perform some of the most incredible kind of microsurgery. Cells were deprived of their tonoplast in order to study the effect of this organelle on other cellular functions. Furthermore, chloroplasts could be removed and re-supplied to individual cells in order to examine the correlation between ion fluxes across the chloroplast membrane and the regulation of plasma membrane transport.

Because of the advantageous geometric features, many of the key techniques in modern plant physiology were first developed, tested and calibrated in characean cells. They were the first to be studied with modern voltage clamp techniques and were used for recording the first quantitative measurements on cytosolic free Ca2+ with various methods. In addition, the turgor pressure probe was initially established in Chara. Verification of the recordings was disburdened by the fact that Chara already represented a well-studied model system for the understanding of water relations in plants.