Charophyceae is a class (biology) of charophytegreen algae, and consist of the single order Charales, commonly known as "stoneworts" and "brittleworts". It is a basal Phragmoplastophyta clade as sister of another unnamed clade which contains the Embryophytes (land plants). Charophyceae are a class within the Streptophyta. Current consensus treats Charophyceae as a class under division Charophyta, with Chlorophyta remaining a distinct division.
Many of the complex traits related to sexual reproduction, photosynthesis, and other defining characteristics of plants evolved first in Streptophytes; analysis of cpDNA (chloroplastDNA), for instance, reveals that many characteristics of plant chloroplasts evolved first in the Streptophyte generaStaurastrum and Zygnema.
The thallus is erect with regular nodes and internodes. At each node there is a whorl of branches. The whole plant is calcified and Equisetum-like. The internodes of the main axis consist of a single elongated cell, in Chara the internodes are corticated covering the main axis. In other genera these are absent. Where there is a single row of cortical cells the cortex is referred to as diplostichous, where there are two rows of cortical cells it is termed triplostichous. The intermodal cells elongate and do not divide they become many times longer than broad.
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