Symbiosis: relationship between two organisms where both gain a benefit greater than could be achieved alone, eg nitrogen fixing bacteria in Fabaceae and mycorrhizal associations in 80% of dicots.
Syncarpous: Having the carpels of the gynoecium united in a compound ovary.
Synconium: A compound fruit composed of fruitlets enclosed in a receptacle or peduncle, eg figs.
Tannins: plant polymers that often bind proteins and function as defences against microbes, insects, and many mammals.
Tap root: the main single root axis from which lateral roots develop.
Taxonomy: classification of organisms, including identification and nomenclature, historically based on morphological features and development but more recently also using genetic information.
T-budding: when a single mature bud is inserted into a T-shaped incision in the rootstock; shield budding.
Testa: outer covering of the seed; the seedcoat.
Thinning: removal of some flowers and/or fruits from plants to increase fruit size and quality, and to balance out yields in plants subject to alternate bearing.
Thorn: hard sharp-pointed stem.
Tolerance: ability to survive under adverse environmental conditions or in the presence of a destructive pathogen or pest.
Top working: changing the cultivar of a tree by grafting selected scion material on the trunk or large scaffold branches.
Translocation: movement of water and dissolved substances through the vascular system of plants.
Transpiration: evaporation of water from the surface of leaves and stems.
Trichome: a hair, bristle, scale or other outgrowth from the epidermis.
Tropism: oriented plant growth in response to a directional stimulus from light, gravity or touch.
Tuber: underground stem in which carbohydrates are stored.
Tubercle: a wart-like swelling.
Turgor: firmness of a cell resulting from its hydrostatic or turgor pressure.
Umbel: inflorescence having the flower stalks or pedicels, nearly equal in length, emanating from a common centre or base.
Vacuole: a membrane-bound fluid-filled cavity within a cell.
Variety: a taxonomic subdivision of a species based on minor characteristics and often an exclusive geographic range.
Vascular bundles: strands of primary phloem and xylem separated by the vascular cambium and often surrounded by a bundle sheath found in shoots but continuous with the vascular cylinder of the root.
Vegetative: referring to non-reproductive structures or growth.
Venation: arrangement of veins in a leaf.
Vernalisation: in some species, the period of cold temperature requirement for flowering.
Vesicular-arbuscular mycorrhiza: non-dense mycelium within the root and extending into the soil; some hyphae penetrate individual cells of the root cortex as well as extending through regions between cells.
Viviparous: Seed germination while the fruit is still on the plant eg ice cream bean.
Water sprout: a vigorous shoot arising primarily from latent buds on the trunk of older scaffold branches.
Waxes: complex mixtures of hydrophobic lipids that make up the protective cuticle that reduces water loss from exposed plant tissues.
Wet feet: a situation where soils remain wet, excluding natural aeration of the soil and roots die.
Whip graft: uses scions and rootstocks of similar diameter in grafting.
Whorl: a ring of three or more structures (leaves, stems etc) in a circle, not spiralled.
Wilting: Plant loss of rigidity leading to a flaccid state, due to turgor pressure falling to zero.
Winter chilling: A period of cold, of temperatures 4-8°C which many temperate species need to effectively come into flower and leaf in Spring.
Withholding period: Indicates the time in days between the last spray and the first harvest.
Xerophyte: plants that are able to grow in very dry, arid climates with minimal rainfall eg olive.
Xylem: vascular tissue that transports water and ions from the root to other parts of the plant.
Zygote: fertilized egg cell.