AgroForestryTree Database
Glossary - G
gall
A pathogen-induced swelling or overgrowth.
gallery forest, riparian forest
Vegetation, with trees and shrubs, growing alongside or close to a watercourse, lake, swamp, or the like, and often dependent on its roots reaching the watertable.
gamete
A specialized haploid cell (sometimes called a sex cell) whose nucleus and often cytoplasm fuses with that of another gamete (from the opposite sex cell) in the process of fertilization, thus forming a diploid zygote.
gamopetalous
With petals fused, at least at the base.
gamosepalous
With sepals fused, at least at the base.
genus
A rather arbitrary category in the taxonomic hierarchy between that of family and species. Genera consist of one or more closely related species; plant genera are defined mostly on characteristics of the flower, fruit or both.
germination
Growth of the embryo in the seed until the emergence of the embryonic radicle through the seedcoat. In seed testing, the capacity of the embryo to emerge from the seedcoat with the essential structures indicates a potential to produce normal plants. In dry seeds, germination follows imbibition (absorbing water and swelling). If the cotyledons emerge above the ground, the hypocotyl appears as the aerial part of the plant (epigeal germination). When both the cotyledon and the hypocotyl remain buried in the soil germination is termed hypogeal.
germinative
Percentage of seeds that germinate during the whole of the germination period, or percentage of seeds that germinate during a specified time interval, determined by the maximum rate of germination.
germplasm
1. The material constituting the physical basis of inheritance (seeds, cuttings, tissue cultures). The sum total of the hereditary materials in a species.
2. The sum total of the genes and cytoplasmic factors governing inheritance. The hereditary material transmitted to offspring through the germ cells.
3. The (sometimes multiple) sets of genes that constitute an individual or a cultivar; a source of genetic material for breeding work.
glabrous
Without hairs or projections.
glabulous
Thickened or swollen.
gland See also nectary
Secreting organ producing oil, resin, nectar, water, etc.
glaucous
With a waxy, greyish-blue bloom.
gley
Soil with impeded drainage. Used in soil classifications based on profile leaching.
globose
Spherical, rounded.
graft (verb) See also grafting
When the graft union between the stock and the scion fails. This can occur after some years of apparently healthy growth.
grafting
1. Placing a portion of one plant in close cambial contact with another with the object of obtaining vegetative union between the two.
2. A method of plant propagation by transplantation of a bud or a scion of a plant onto another plant. Also, the joining of cut surfaces of 2 plants so as to form a living union.
grassland See also rangeland, veld
Land covered with grasses and other herbaceous species. Woody plants may be present, but if so, they do not cover more than 10% of the ground. There are many different types of grassland designated by ecozone, topography, climate, soil conditions, and so on. Derived grassland is maintained in that condition by regular burning; edaphic grassland arises on particular soil types, for example, those found in or around permanent or seasonal swamps.
gravelly
Soil texture when soil mass contains 15-90% pebbles by volume.
grazing See also browse
A method of feeding by herbivores characterized by repeated removal of only a part, generally the leaf, of the plant, which is most commonly called herbage. Defoliation by herbivorous animals.
green manure
1. A crop grown for soil protection, biological nitrogen reduction, or organic matter and ploughed, disked or hoed into the soil.
2. Any crop grown for the purpose of being turned under while green, or soon after maturity, for soil improvement.
gregarious
Species that occur in groups within a community and that may form pure stands of species in the natural state.
ground cover See also herbaceous layer
1. A crop planted to provide a covering over the soil.
2. Any vegetation producing a protective mat on or just above the soil surface. In forestry, low-growing shrubs and herbaceous plants under the trees.
ground flora
The grasses, herbs and other plants growing on the forest floor.
groundwater See also water table
The water below the land surface that has drained through the upper soil layers.
growing season
Period(s) of the year during which water is available for plant growth and temperatures are favourable (not too high or low). It is generally poorly defined, and usually used only with regard to crop plants.
growth habit
The basic pattern of structural development or symmetry attained by a plant, for example 'shrubby', 'treelike' or 'viney', 'erect' or 'spreading'.
grubbing
Felling trees and shrubs by exposing and cutting the roots. Same as 'grub felling'.
gummosis
Production of gum by or in plant tissue. Sometimes caused by bacterial infection.
gynaecium (gynoecium) See also androecium
The collective term for the female reproductive organs of a flower, comprising one or more carpels.
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