Gross Primary Production (GPP) - Referring to the total amount of energy which is fixed into bond energy of complex organic molecules by producers through photosynthesis in an ecosystem in a unit time. It implies the total production of photosynthates per unit time in the ecosystem and has been found to depend on the photosynthetic efficiency of producers.

Ground Meristem - Those parts of an apical meristem which gives rise to the ground issue.

Ground Respiration - The respiration of roots, which is not salt absorption.

Ground Tissue - The general mass of parenchyma which is present outside and between the vascular strands of a young stem or root.

Growing Point - The apical meristem of axis, in which cell-division occurs, and differentiation begins.

Growing Zone - The portion of an organ in which elongation proceeds.

Growth - Used for describing the increase in size and dryweight of a plant, cell which cannot be reversed. It does not include the increase in size due to the uptake of water.

Growth Correlation - Said of relationship which exists between different growth rates of various parts of a plant body. Growth rates have been found to depend on the balance of growth substances in the region and competition between different parts of the plant for nutrients.

Growth Curvature - Used for describing the curving of an elongating part of a plant organ, due to one side growing faster than the other.

Growth Factor - Any substance affecting growth rate of a plant or its part. This termcovers food reserves and minerals and also various growth substances and inhibitors occurred in the plant systems.

Growth Inhibiting Substance - A substance formed inside the cells, which slow down or stop growth, often in some other part of the plant.

Growth Promoting Substance - A substance which tends to promote or accelerate growth. It may be formed inside the plant, or may be obtained from an external source same as an annual ring.

Growth Substance - ( hormone, phytohormone). Said of any sub stance which produces marked and specific effect on some aspect of plant growth when present in very low concentrations.

GTP(guanosine triphosphate). - A nucleoside triphosphate having the base guanine which is formed from GDP and phosphate during deacylation of succinyl CoA to succinate in TCA cycle.

Guard Cells - A pair of reinform cells which are bounding a stoma. The walls are differentially thickened, and the cells have chloroplasts.

Gullet - Said of an invigination which is present at the anterior and of the cell of euglenoid cell. It has an expanded basal region or reservoir, the cytopharynx and cytosome. In the region without pellicle in the reservoir, particles can be taken into the cytoplasm by endocytosis.

Gummosis - A pathological condition which is usually physiological, or caused by bacteria. The cells dry-out causing an enzymatic break-down of the cell-walls to form a gum.

Gums - These are colloidal plant products, which either disssolve, or swell in water. When hydrolysed they give complex organic acids, pentoses and hexoses.

Gutta - (1) An oil drop in a spore or fungal hypha. (2) A general term for a small vacuole.

Guttation - Used for describing the secretion of water from hydathodes, which are commonly present at the end of the main veins of leaves.

Gutter-Pointed - Pointed with the point channelled above to form a spout.

Gynandrous - Said of stamens that are inserted on the gynoecium.

Gynoecium (gynaecium) - Used for describing the female reproductive organ in angiosperms which is made up of one or more carpels. It is present in the centre of flower though in more advanced forms it may not be symmetrically placed.

Gynymonoecious - Said of plants bearing female and hermaphrodite flowers on the same individual e.g., many members of Compositae.

Gynophore - Used for describing an extension of the receptacle between and roecium and gynoecium that bears ovary as in many members of Capparaceae.