THALAMUS: A receptacle; the end of the flower stalk where the flowers are carried, which is often slightly enlarged.
THALLIFORM: Having the form of a thallus.
THALLOID: Resembling or consisting of a thallus.
THALLUS: The body of mosses, lichens, algae, and fungi, plants without leaves, roots, or stems.
THECA: A case or sac; it's generally the same as a capsule.
THERMOMETER: An instrument used to measure temperature.
THERMOTROPIC: Plant movement that is determined by temperature.
THORN: A sharp, stiff, woody, spine, which is ordinarily on a plant's branch or stem, such as on a Rose.
TREE-LEAVED: Having three leaves or leaflets, as many species of Trifolium; also called trifoliate or trifoliolate.
THROAT: The mouth or orifice of a corolla or calyx, being the place at which the tube joins or expands into the limb.
THYRSE: A flower cluster with a central spike that has side branches also clustered with flowers, such as a Horse chestnut and lilac.
THYRSOID: Resembling a thyrse.