Gland (botany)

Glands in a leaf of St. John's wort

The glands of plants are single cells, tissues, or intercellular ones that secrete secretions . The endoplasmic reticulum , the Golgi apparatus and the cell nucleus are often strongly developed in the gland cells.

Functions of the secretions

The secretions formed in the cytoplasm perform various functions:

Milky sap, gum and resins seal wounds.
Essential oils, fragrances and nectar are used to attract animals.
Alkaloids and steroid glycosides contained in secretions deter herbivores .
In salty locations, plants secrete excess salts via salt glands.
Carnivorous plants, such as the sundew family , form sticky secretions with which they catch insects and then digest them with exoenzymes from digestive glands.

The shape of glands is just as diverse as their functions:

When intercellular spaces take on a glandular function, they are surrounded by chlorophyll-free cells. Examples are the glands in the leaves of St. John's wort , which appear as small bright spots, and the glands in the peel of lemons and bitter oranges.
Superficial glands like the nectaries contain cylindrical or prismatic cells. The cuticle above it is lifted by the secretions and later perforated.
Other forms of plant glands are glandular hairs and water-separating hydathodes .

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