Abstract/Summary:
The bottom zone of the pitcher of the carnivorous plant Sarracenia was investigated using light and electron microscopy. The rectangular epidermal cells have dense cytoplasm with a large nucleus, many mitochondria and chloroplasts. The cuticular membrane is thin, its cutinized layer becoming discontinuous during the maturation of the pitcher. The anticlinal walls of the epidermal cells are partly lignified and seem to permit apoplastic diffusion. The hypodermal cells are provided with a secondary suberized wall, and a silver hexamine positive "plug" fills the gap between neighbouring hypodermal cells. The hypodermis therefore resembles the bundle sheath cells of certain grasses. Simple pits traversed by many plasmodesmata connect each hypodermal cell with its neighbouring epidermal, hypodermal and mesophyll cells. The structure and development of the pitcher epithelium is described and its function discussed.