Diaphragm of Calamites Longitudinal section of a stem of
Calamites with a node or diaphragm.
The dark colour indicates that in the
diaphragm sugars were stored.
The bark has disappeared and the
lightcoloured, elongated rectangular cells
inside the cavity are part of the pith.
This is a photo from a coal ball slide.
The width of the stem is 4 mm.