On Food and Cooking

Vascular tissue runs through the ground
tissue, and resembles our veins and arteries. It
is the system of microscopic tubes that
transport nutrients throughout the plant. The
work is divided between two subsystems:
xylem, which takes water and minerals from
the roots to the rest of the plant, and phloem,
which conducts sugars down from the leaves.
Vascular tissue usually provides mechanical
support as well, and is often tough and fibrous
compared to the surrounding tissue.
Dermal tissue forms the outer surface of
the plant, the layer that protects it and helps it
retain its moisture. It may take the form of
either epidermis or periderm. The epidermis is
usually a single layer of cells that secretes
several surface coatings, including a fatty
material called cutin, and wax (long
molecules made by joining fatty acids with
alcohols), which is what makes many fruits
naturally take a shine. Periderm is found
instead of epidermis on underground organs