Garigue - (garrigue). A type of scrub woodland characterically on limestone areas which have thin, poor, dry soil and low rainfall. Vegetaion is low growing and consists of aromatic, often spiny, species e.g., Salvia officina lis, Thymus, Lavanduala  vera etc.

Gas Vacoule. Used for describing a large cavity in the cells of the Cyanophyta. They may have gas or a viscous substance, and may help to increase buoyancy.

Gegenpol - Use for the pole of a resting nucleus, which lies far thest from the centrosome.

Gelatinous Fungi - (Jelly fungi). Used for describing fungal members of order Tremellales of Hymenomycetes that produce gelatinous basidiospores. They include about 200 species of 26 genera. They are found usually on dead wood.

Gemma - A cell, or group of cells which is involved in asexual reproduction. Found in some aglae, fungi and bryophytes.

Gemma Cup - A cup-or crescent-shaped outgrowth from the gametophyte of some liverworts. It contains the gemmae.

Gene - One of the units of inherited material which is carried on a chromosome. They are aranged in a linear fashion, and are indivisible, but capable of self replication. Each represents a unit character, which has been recognized by its effect on the individual bearing the gene in its cells. There are 1000 genes in each nucleus.

Gene Bank - An institution in which plant material which is in danger of becoming extinct in wild conditions or being lost from cultivation, has been stored. in a viable condition, nor mally as reproductive propagating organs.

Gene Centre - (centre of diversity). The area showing considerable genetic diversity of certain crop plants and their relatives. Certain such centres (primary centres) are regarded to be the regions of origin of particular crops e.g., Middle East for wheat.

Genecology - Dealing with the variation in gene frequency within a species in relation to environmental change.

Gene Flow - Describing the movement of genes between populations of the same species due to interbreeding.

Gene Frequency - Used for proportion of an allele in the population compared with that of other alleles of that gene. Suppose a gene A has alleles A and a and frequency of a =0.2 (20%) then that of allele A=0.8 (80%) since a+A=1 (100%).

Gene Mutation - 0Used for describing any alteration in a single gene which involves a change in the number, type or sequence of bases in a polypeptide due to some external or internal agent.
Gene Pool - Said of the sum total of all the variety of genes and their alleles present in a breeding population or species at a time.

Generation Time - The time taken by a unicellular organism between one cell division and the next.

Generative Cell - A cell in the pollen grain of the gymnosperms which gets divided to give a stalk cell and a body cell.

Generative Nuclei - In angiosperms, the two male gametes are
formed by division of generative cell. Then, they migrate downs the pollen tube behind the vegetative nucleus find are released in to the embryo sac by dissolution of the tip of pollen tube and then one of them undergoes fusion with egg cell to form zygote and other one undergoes fusion with polar nude to form primary endosperm nucleus.

Genetic Code - Used for describing the sequence of nucleotides in the polypeptide of DNA in an organism which is having the information to code for a molecule of protein.

Genetic Drift (Sewall Wright effect). A change in the frequency of gene which has taken place due to pure chance instead of any natural selection. It occurs in small populations.

Genetic Engineering (recombinant DNA technology). Dealing with the isolation of useful gene(s) from a particular donor organism or its tissue and the incorporation of this gene into other organism that normally does not have the gene.

Genetic Erosion - Describing the loss of genetic variation and consequent narrowing of genetic base of cultivated plants due to large scale introduction and cu1tivation of suitable varieties that will replace the locally adapted primitive varieties.

Genetic Load - The proportion of disadvantageous genes which are present and maintained in the population. It has three components: mutational load, segregation load and Substitutional load .

Genetic Resources - Used for describing deversity and availability of allelels in both natural and artificially maintained stocks of organisms.

Genetics - The science of heredity, which deals with the study of its chemical fundation, its developmental expression and its bearings on variation, selection adaptation, evolution, breed ing and the activities of man.

Genetic Spiral A hypothetical line drawn on a stem which is passing by the shortest path through the points of insertion of successive leaves.

Genome - A complete set of haploid number of chromosomses present in an organism. A diploid has 2 genomes usually if it is not an interspecific hybrid where it has two different genomes, Number of chromosome in a genome is represented by the symbol x. In diploid, 2x=2n but in tetraploid, 2n=4x or in hexaploid, 2n=6x.

Genotype - Used for describing the genetic constitution of an organism which is opposed to its phenotype.

Genus - A taxonomic rank having related species, Similar genera are collected into a family.

Geological Time Scale - The scale which is representing periods of past time on the basis of geological evidence obtained from study of rock strata where they get exposed due to natural causes or by human activity.

Geophyte - A plant which perennates by subterranean buds.

Geoplagiotropic - Growing in a direction at an angle to the ground surface.