G-J

G

gallery 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. Also called a riparian forest.

gene bank

For plants, any place established with the appropriate facilities and trained staff where plant germplasm can be maintained in the form of seeds or tissues or as growing plants.

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 seed coat with the essential structures indicates a potential to produce normal plants. In dry seeds, germination follows imbibition (absorbing water and swelling).

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.

green manure

1. A crop that is 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

H

hardwood

The timbers from broadleaved, angiosperm trees often, but not always, harder than the timber from conifers (softwoods). They are often, but not always, deciduous (Eucalyptus, for example, are hardwoods).

heartwood

1. The inner of two distinct wood layers in the trunk of many trees. The outer layer, usually lighter and moister, called sapwood, is newly formed wood with some living cells. Inside this ring of sapwood is often a darker, harder, more durable core called heartwood. A striking example of heartwood and sapwood difference is found in Dalbergia melanoxylon, which has light brown sapwood and purple black heartwood; it is often used for craft carving.

2. The wood in the centre of a tree, no longer in use for conducting water from the roots to the leaves. It is often darker in colour than the outer wood (sapwood) and may contain chemicals that make it more resistant to decay.

hedge

Bushes or shrubs or trees planted in a row and trimmed. Used to separate one piece of land from another.

hedgerow

A barrier of bushes, shrubs or small trees growing close together in a line. A hedge is similar but pruned.

homegarden

A land-use form on private lands surrounding individual houses with a definite fence, in which several tree species are cultivated together with annual and perennial crops; often with the inclusion of small livestock. There are many forms of such gardens varying in how intensively they are cultivated and their location with regard to the home, for example, village forest gardens, 'compound gardens', 'kitchen gardens'.

I

indigenous

Native to a specified area, not introduced. An indigenous tree is one that grows naturally within a specific environment or within certain predetermined boundaries.

industrial forestry

Large-scale, commercial tree planting for timber and other wood products (for example, wood chips).

in situ

'On the site'. When applied to tree plantations, refers to seed planted in the same area as it was collected.

in vitro

In a laboratory (strictly 'in glass', that is, a test tube). For example, the digestibility of animal feeds may be estimated by appropriate chemical methods 'in vitro' in a laboratory; 'in vivo' (in the animal itself) using a fistula (narrow tube) to extract material ingested after it has been through the rumen (first stomach), or later, to see what has been absorbed; or, ultimately, by live weight gain per amount of intake.

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