Growth.
The whole of the time during which a cell organ or plant part increases in size, slowly at first, then faster, then faster and more slowly again until it is mature.

Grey Matter. Tissue of vertebrate control nervous system containing numerous cell-bodies and dendrites of nerve cells; and unmyelinated terminations of nerve-fibres forming synapses with these; together with glia and blood vessels. Occurs mainly as an inner layer surrounding central canal; but occurs also as a superficial layer (cortex) on cerebellum and cerebral hemisphere. It the tissue of the nuclei or centres. The co-ordinating work of the C.N.S. is done in grey matter by the large numbers of synapse present.

Grooming. Licking, scratching and picking over the fur of mammals; either to self or of other membrane of the species.

Guard Cells.
Specialized, crescent-shaped epidermal cells occurring in pairs surrounding stomata. Changes in shape of guard cells, due to changed in their turgidity, control opening and closing of stomata and hence affect loss of water vapour and gaseous exchange.

Gymnospermae. A class of vascular plants. The seeds are exposed on the sporophyll, i.e. the sporophyll is not infolded to form an ovary; and the endosperm is formed before fertilization.

Gynandromorph. Any animal exhibiting both male and female features, often with the body divided into equal portions of the two sexes.

Gynobasic. (Of a style), arising from base of ovary (due to infolding of ovary wall during development), e.g. white dead nettle.

Gynodioecious. Having female and hermaphrodite flowers on separate plants.

Gynoecium. (Pistil). Collective name for the carpels of a flower.

Gynomonoecious.
Having female and hermaphrodite flowers on the same plant.