Glossary of Gardening Terms

Index T

Tap Root:
   A primary, sparsely-branched root which may penetrate to considerable depth. (e.g., carrot)
Taxon:
   Named group of organisms that is defined by a set of shared characters. Taxonomy is the science of classification, nomemclature, and identification of organisms.
Temperate:
   Refers to zones located between the subtropics and the polar circles , which experience distinct seasons, without temperature extremes. Rainfall occurs throughout the year.
Temperate greenhouse:
   Greenhouse with a minimum temperature of 7C (45F)
Tender plant:
  Plants of tropical origin which are damaged by exposure to low temperature 5C (41F) that are above freezing. In extremely tender plants, damage may begin to occur at 10C.
Tendril:
   A slender twining modified leaf, leaflet or stem used as a grasping means of support. (e.g., the terminal leaflets on a pea)
Tepal:
   Sepals and petals of a lily or tulip flower which very similar, and difficult to tell apart.
Terminal:
   Located at the end of a stem, shoot, or other organ.
Ternate:
   Formed or arranged in threes.
Terrarium:
   An enclosed, glass or plastic container in which plants are grown.
Terrestrial:
   Describes a land plant that grows in soil, rather than epiphetically, as a parasite, or in water.
Tessellated:
   With a bold, chequered pattern that contrasts with the ground colour; usually describes corolla markings.
Test winter:
  An unusually cold winter that will damage or kill semi-hardy plants.
Thatch:
   The layer of dead stems that builds up under many lawn grasses. Thatch should be removed periodically to promote better water and nutrient penetration into the soil.

Thin:

Thin out:

   To remove a number of buds, flowers, seedlings, or shoots to improve the growth and quality of remaining ones.
Thorn:
   A sharply pointed structure formed from a modified branch.
Throat:
   Opening of the tubular part of flower, from where the petals or tepals spread.
Tissue:
  A group of similar cells which function together to perform a specific function. (e.g., xylem tissue transports water through a plant)
Tincture:
   Alcoholic solution of vegetable essences used medicinally.
Tomentose:
   Woolly.
Toothed:
   (dentate) Describes a margin, usually of a leaf, with tooth-like, triangular indentations. Double toothed margins have alternate large small teeth.
Top-Dress:
  

Apply fertiliser or mulches to the soil surface around the plants.

To apply organic and inorganic dressing to lawns to feed and improve the texture of the grass.

To apply material such as stone or grit, usually decorative, to the surface of the soil or potting compost, around a plant, in order to improve drainage and reduce moisture loss.

To renew the upper layers of potting compost in a container instead of 'potting on' the plants.
Topiary:
   The art of clipping and training of trees or shrubs to form free, geometric or representational shapes.
Topsoil:
   Uppermost layer of the soil, usually the most fertile.
Trademark Name:
   Name licensed for commercial use, and distinct from a registered cultivar name .
Trailing:
   (see climber)
Train:
   To prune and shape the growth of any plant.
Transmission:
   The transfer of spread of a virus or other pathogen from one plant to another.
Transpiration:
   The loss of water vapour from a plant through stomates.
Transplanting:
   The process of digging up a plant and moving it to another location.
Tree:
   Woody perennial with a crown of branches developing from the top of a usually single trunk or stem.
Tree fern:
   Large fern that develops a treelike trunk in maturity.
Triangular:
   (deltoid) With 3 sides of equal length. A triangular leaf is attached to the stem at a point midway along one side.
Trifoliate:
   A compound leaf having three leaflets.
Trifolioliate:
   Palmate.
Trigeneric hybrid:
   Offspring of 3 genera, crossed over 2 generations.
Trigonal:
   Three-sided.
Tripartite:
   Divided almost to the base into 3 lobes or segments.
Tripinnate:
   (3-pinnate) see pinnate.
Tropical:
   Refers to the zone between the Tropics Cancer and Capricorn, with a hot, steamy climate that encourages lush growth. Rainfall may occur throughout the year or mainly during a monsoon season.
Tropical plant:
   Any plant that originate from tropical climates.
True:
   (true-breeding)Term applied to plants that, when raised from seed, virtually reproduce the characteristics of the parent.
Truncate:
   Ending abruptly as though cut off at a right-angle.
Truss:
   Compact cluster of flowers or fruit.
Tuber:
  An enlarged, fleshy, underground tip of a stem modified for storage. (e.g., potato)
Tubercle:
   Nodule, hard swellings, e.g. On roots of leguminous plants harbouring nitrogen-fixing Bacillus.
Tuberous root:
   An enlarge, fleshy underground root specialised for storage. (e.g., sweet potato).
Tufa:
   Porous, moisture-retentive limestone rock, used for the cultivation of alkaline-loving, rock-dwelling alpines.
Tunic:
   Membrane covering bulbs and corms, often papery but sometimes thick and leathery.
Tunicate bulb:
   A bulb where successive layers of modified leaves wrap completely around the bulb.
Turion:
   Detached, often fleshy bud of an aquatic plant that overwinters at the bottom of a pond, regenerating in spring.
Turkscap:
   Refers to a flower resembling a traditional Turkish cap with petals strongly reflexed.
Twining:
   (see climber)
Type species:
   Individual embodying the distinctive characteristics of the species.

Last updated 10 March, 2002
© copyright 1999, P. A. Owen