A gland is an organ that manufactures or discharge chemical
substances to be used in, or eliminated from, the body . A gland may
vary from a single cell to a complex system of tubes that unite and open
onto a surface through a duct.
Simple glands are common in the plantkingdom. The sweet
nectar of flowers and the
resinous pitch of pine trees are
substances produced by plant glands. Vegetal glands are special, usually
minute and globular, organ,
embedded or projecting from the surface of the plant that
excretes a variety of
liquid substances that have various purposes, hence glandular.