Senescence and Post‐mortem Changes in the Ultrastructure of Sphagnum Fuscum (Klinggr.) Schleich Leaf Cells

Summary Sphagnum fuscum (Klinggr.) Schleich leaves collected from various depths down to 40 cm from the surface were examined by light and electron microscopy and for their capacity to regenerate. Leaf cells never produced new plants: all regeneration in the subsurface samples was from small groups of cells on branches near the junction with the main stems. Non‐hyaline leaf cells produced in the early summer are senescent by the autumn and dead within a year. Although all the organelles disintegrate these cells invariably contain large lipid globules even to a depth of 30 cm. Fungal hyphae were often found in the non‐hyaline leaf cells from all depths and were frequently associated with eroded lipid bodies. The hyphae spread from cell to cell through the end walls between adjacent non‐hyaline leaf cells at the sites of plasmodesmata. Lipids may be the major catabolite for the fungi within old shoots of Sphagnum.