stonewort The common name for the brittle, calcified plants of the Charophyta; Chara and Nitella are the commonest British genera. The plant consists of a ‘stem’ or axis which bears whorls of branches at intervals (nodes) along its length. The axis is attached at its base to the substratum by means of branched rhizoids.

stone·wort / ˈstōnwərt; -ˌwôrt/ • n. a freshwater plant (Chara and other genera, class Charophyceae) with whorls of slender leaves, related to green algae. Many kinds become encrusted with chalky deposits, giving them a stony feel.