The vacuoles in the epidermal cells of light-grown seedlings ofPolygonum cuspidatumwere found to contain intensely pigmented spherical bodies (anthocyanoplasts). Dark-grown seedlings contained similar spherical bodies that were unpigmented. The unpigmented spherical bodies accumulated anthocyanin and turned into anthocyanoplasts when dark-grown seedlings were irradiated. The unpigmented spherical bodies of dark-grown seedlings were heavily stained upon treatment of seedlings with neutral red. The absorption spectra of spherical bodies and vacuoles showed that the contents of the spherical body were different from those of the vacuole. The spherical body was stable in darkness or at low temperature but was unstable at 25°C in the light. There was no correlation between the amount of anthocyanin and the percentage of cells that contained spherical bodies, suggesting that, inP. cuspidatum, the spherical body is not the main site of anthocyanin synthesis
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