AgroForestryTree Database
Glossary T
tannin
An astringent substance, available naturally in the bark (and sometimes the wood) of different species of trees (for example, acacia and mangrove species); used in converting hide to leather. A polyphenol.
taper See also tree form
The decrease in thickness, generally in terms of diameter, of a tree stem or log from the
taproot See also sink root
1. Main root, leaving the collar in the opposite direction from the stem and growing more powerfully than the secondary roots.
2. Primary root that persists and maintains its dominance; often swollen and providing for storage.
taungya system
Method of raising forest trees in combination with (seasonal) agricultural crops. Used in the early stages of establishing a forest plantation. It not only provides some food but can lessen the establishment costs.
taxon
A taxonomic unit of any size. A category in the taxonomic hierarchy.
taxonomy
Classification of organisms, including identification and nomenclature, according to a natural (chiefly morphological) system that seeks to depict evolvement. Hence taxon, any designated group within a classification (for example, a cultivar, a species).
tendril
Part or all of a stem, leaf or petiole modified to form a delicate, thread-like appendage; a climbing organ with the ability to coil around objects.
terminal
Situated at the apex.
ternate (of leaves)
Compound, divided into three parts more or less equally. Each part may itself be further sub-divided.
tessellated (of leaves)
Marked with a fine chequered pattern, like a mosaic.
testa
The outer protective covering of a seed.
tetramerous
Having parts in fours.
thallus
A type of plant body not differentiated into root, stem or leaf.
therophyte
A self-supporting annual (or seasonal) plant whose shoot and root systems die after seed production and that completes its whole life cycle within 1 year (season).
thicket See also brush
1. A number of trees or shrubs growing close together.
2. A closed stand of bushes and climbers between 3 and 7 metres tall.
thinning See also line thinning, mechanical thinning, selective thinning
Removal of some of the plants from a crop, or immature trees from a forest, to improve growth of the remainder.
thinning out
A type of pruning operation in which entire shoots are removed. An extension of, or complement to, heading back.
throat
The site in a calyx or corolla of united parts where the tube and limbs meet.
thyrse (of inflorescences)
Densely branched, broadest in the middle and in which the mode of branching is cymose.
timber See also lumber
The wood product of a tree obtained by sawing and milling. Timber is a major product of forests. It differs from poles or roundwood only in that it is cut.
timber height
The height of a tree to the point at which the stem breaks into branches (the 'crown spring') or to the point at which the diameter of the stem is 7 cm over bark, whichever is reached first. On a felled tree this point is called the 'timber point'.
timberbelt
See windbreak.
tomentose
Densely covered in short hairs.
topsoil See also subsoil
The upper layer of soil, rich in organic matter. It forms naturally but is easily lost through disturbance.
tracheid (cell)
One of the long cylindrical tapering cells in a tube-like series of non-living cells involved in supplying of mechanical support and transport of water and salts. The cell is dead and the wall has bands of lignin in it, which adds structural strength.
translocated herbicide See also contact herbicide, systemic
A herbicide that, after uptake, is moved within the plant and can affect parts of the plant remote from the point of application.
transplant See also balled roots, pricking out
1. A plant that has undergone the process of transplanting, as differentiated from a seedling or cutting, which has not. In a forest nursery, seedlings are normally transplanted after 1 or 2 years in the seedbed so as to develop a better root system and a sturdier plant.
2. To take a tree or plant from one location and plant it in another. Transplanting happens in many forms: with seedlings in pots, with open-rooted seedlings, balled-root seedlings and with stumps.
tree See also bush, shrub
A woody plant having one well-defined stem and a more or less definitely formed crown and roots, usually attaining a height of at least 2 metres.
tree farming See also farm forestry
Any agroforestry practice that incorporates trees into farmland.
tree form
The degree and mode of taper in a tree or log. Also loosely applied to the general shape of the bole and its desirability for use.
tree garden See also homegarden, mixed garden, village forest garden
A multistoreyed agroforestry system in which a mixture of several fruit and other useful trees is cultivated (that is, for a mixture of products), sometimes with the inclusion of annual crops.
tree height
The vertical distance between the extreme top of a standing tree (even if this is a lateral shoot) and ground level. If the tree is on a slope, the height is measured using the upper side of the slope as the ground level.
tree temperament See also climax species, pioneer
The set of growth and development reactions shown towards its environment by a tree species during its whole life cycle.
trichome
A hair-like outgrowth.
trigonous
Triangular in cross-section.
trunk See also bole
The main stem of a tree.
tube See also limb
The united, usually cylindrical part of the calyx or corolla made up of united parts.
tuber
1. A greatly swollen underground shoot or stem, generally irregular in shape, that acts as a store of nutrients.
2. A specialized stem; the enlarged fleshy tip of an underground stem.
turf See also sod
The leafy shoot system together with the upper part of the roots cut and lifted (for relaying) from a grassy sward. Hence a 'turfed' area.
twig
Stem 1 year old or less. Usually applied to a stem not including the leaves.
twiner See also root climber, scrambler
Plants that climb by having stem apices that nutate (oscillate and wind) around slender supports.
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