Cephalotus follicularis - Stoma-gland
Small ’stoma-gland’ from a gland patch surrounded by two immobile crescent-shaped ‘guard cells’.
Section of photo at right showing pit field with plasmodesmata. The gland cell is at the bottom.
Section through ’stoma gland’ with ’guard cells’ and basal cell.
It is recommended to see the pictures and the discussion of the ‘vulcan-glands’ before continuing on this page.
The numerous small glands of the dark gland patches are here named ‘stoma-glands’ since they obviously develop in connection with two guard cells from converted stomata. Normally only one gland cell is present filling the intercellular space between the two open but immobile ‘guard cells’. As shown on the right Fig. above, two gland cells may be present. The gland cell rests on a basal cell. There are large pit-fields and numerous plasmodesmata (left Fig. above) between the gland cell and all surrounding cells except the ‘guard cells’. However, there are no cutinized endodermoid cells present, and the outer wall of the gland cell is without a cuticle (lower right Fig.). This means there are free transport possibilities through both the living cytoplasm and the dead cell walls. This is opposite the situation in both the ‘vulcan-glands’ and the nectaries. Therefore, it is most likely that the ‘stoma-glands’ are digestive glands with absorbing function. The very electron-dense appearance of the outermost cell wall and the positive reaction for protein on the color photo below can be interpreted as an accumulation of nutrients from the pitcher fluid onto their way into the plant following a concentration gradient. The black dots along the cell membrane on the right Fig. below further indicate transport activity across the cell membrane, and since endodermoid cell walls are lacking, it is most obvious to assume the transport is directed inwards.