Our ‘A’ to ‘Z’ of Gardening Terms

Terms that begin with “T”

tanninA substance occurring in the bark and leaves of some plants that helps protect against predators.
taprootA thick central root attached directly to a plant’s crown. Taproots branch little, if at all.
taxonomyClassification or naming of plants or animals.
temporary branch(1) A small shoot or branch left on a young tree’s trunk for protection and nourishment. (2) A low lateral allowed to remain until a tree is tall enough to have scaffolds at the desired height.
tenderNot tolerant of frost or cold temperatures. In horticulture, tender does not mean weak or susceptible to insect pests or disease.
tendrilA slender projection used for clinging, usually a modified leaf. Easily seen on vines such as grapes and clematis.
terminalThe tip (apex), usually of a branch or shoot.
terminal budThe bud at the tip of a stem, trunk, or branch. Its development extends the plants growth.
thatchA tightly intermingled layer of stems, leaves, and roots, living and dead, that forms between the soil surface and green vegetation of grass.
thermoperiodThe change in temperature from day to night.
thermophillicHigh temperature, as in microorganisms that break down organic matter in a hot compost pile.
thigmotrophismA growth response to touch.
thin(1) To remove an entire shoot or limb where it originates. (2) To selectively remove plants or fruits to allow remaining plants or fruits to develop.
thornA hard, sharp-pointed, leafless branch. Hawthorne is an example of a plant that produces thorns. See prickle.
tillerA shoot that arises from a plant’s crown. Generally associated with grass species.
tissueA group of cells of the same type having a common purpose.
tissue cultureThe process of generating new plants by placing small pieces of plant material onto a sterile medium. Also called embryo culture.
tolerantA plant that will produce a normal yield even if infested by a disease or insect pest. See immune, resistant.
topiaryA tree or shrub shaped and sheared into an ornamental, unnatural form, usually a geometric shape or the shape of an animal.
totipotencyThe ability of any cell to develop into a complete plant.
trace elementSee micronutrient.
transpirationThe process of losing water in the form of vapor through stomata.
transpirational pullThe force exerted by transporation from the leaves which draws water up through the plant.
treeA woody plant that typically grows more than twelve feet tall and has only one main stem or trunk.
tropismThe tendency of a plant to turn in response to an external stimulus, either by attraction or repulsion, as a leaf turns toward the light. See geotropism, phototropism.
trunkThe main stem of a tree. Also called a bole.
trussA flower cluster, usually growing at the terminal of a stem or branch.
tuberAn underground storage organ made up of stem tissue. Contains buds on the surface, from which shoots may arise. Potatoes are an example.
tuberous rootAn underground storage organ made up of root tissue. Sprouts only from the point where it was attached to the parent plant. Dahlias are an example.
turgorCellular water pressure; responsible for keeping cells firm.
twigA young stem (one year old or less) that is in the dormant winter stage (has no leaves).
twinerA stem growing in a spiral fashion around a support.