Salt glands of the mangrove The salt glands of
mangroves such as
Acanthus,
Aegiceras,
Aegialitis and
Avicennia are a distinctive multicellular
trichome, a glandular hair found on the upper leaf surface and much more densely in the abaxial indumentum. On the upper leaf surface they are sunken in shallow pits, and on the lower surface they occur scattered among long nonglandular hairs composed of three or four cells. Development of the glands resembles that of the nonglandular hairs until the three-celled stage, when the short middle stalk cell appears. The salt gland continues to develop to produce two to four vacuolated cells at the level of the epidermis, the stalk cell with an almost completely cutinized wall, and at least eight terminal cells. The terminal cells have a thin, perforated cuticle which separates from the cell walls apically, leaving an enclosed cavity between them. The secreted salt evaporates and forms visible crystals.
Cannabinoid-secreting glands of Cannabis Cannabis plants are broadly covered with sessile glands, and other hairs throughout above-ground portions of the plant. There is a particularly high concentration of glands on the
bracts of the female plant. After flower formation begins, some of the glands, especially on bracts near the flowers, develop stalks projecting them outward from the plant surface. The glands consist of a layer of disk cells, whose outer surface splits to create a large secretory cavity lined by cell wall and cuticle components. Together the disk cells and secretory cavity form a round head atop the narrow stalk. These cavities come to contain large amounts of
cannabidiol in
hemp-producing strains, or
tetrahydrocannabinol and
cannabinol in other
cannabis plants. These compounds appear to be produced beginning in specialized
plastids called
lipoplasts. These produce spheres of oily secretions, including
terpenes, which pass through the cell membrane and wall to accumulate as vesicles in the secretory cavity. Final reaction to cannabinoids appears to occur outside the disk cell cytoplasm. The glands gradually darken as they mature, with loss of cannabinoids over time (perhaps to evaporation) and eventually undergo
abscission from the plant.
Myrmecophytes Glands are used by myrmecophyte plants to feed their ant symbiotes. == References ==