and older tissues, and has a dull, corky
appearance. Our culinary experience of
periderm is usually limited to the skins of
potatoes, beets, and so on.
Secretory tissue usually occurs as isolated
cells on the surface or within the plant. These
cells correspond to the oil and sweat glands in
our skin, and produce and store various aroma
compounds, often to attract or repel animals.
The large mint family, which includes other
common herbs like thyme and basil, is
characterized by glandular hairs on stems and
leaves that contain aromatic oils. Vegetables
in the carrot family concentrate their aromatic
substances in inner secretory cells.
The three kinds of plant tissue in a stem.