Anatomical characteristics of peatified Calluna vulgaris stems isolated from a selection of Northwest European raised bog peat deposits were compared with intact stems in order to reveal anatomical modifications caused by the peatification process. Four main decomposition processes were discerned: (1) loss of structural integrity of cell walls and cell inclusions; (2) gelification and swelling of cell walls; (3) discolouration of cell walls; and (4) deposition of matter in cell lumina.

Int. J. Coal Geol.

van der Heijden, E., Bouman, F., & Boon, J. J. (1994). Anatomy of recent and peatified Calluna vulgaris stems: implications for coal maceral formation. Int. J. Coal Geol., 25, 1–25.