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TERMGROUPDEFINITION
TAGMA (TAGMATA)NANIMALSPronunciation:

Etymology: from the Greek σύζυγος (syzygos), “‘yoked together’”).

Tagma (tagmata, pl.) is the body region formed by the fusion of segments in metamerically segmented animals like arthropods.
TAXON (TAXA)NSYSTEMATICSPronunciation:TA-kson

Etymology: Taxon is derived from the Greek word for tidiness (taxis, τάξις). Linnaeus (1812) defined taxonomy (names of taxa) to mean the ordered arrangement of living things.

A taxon (taxa, pl.) is a member of any taxonomic unit (species, genus, family, etc.).

Taxa can be of three different types:

Natural: A natural taxon is monophyletic.

Artificial: An artificial taxon includes taxa that are not related or just look alike. Many such artificial taxa occur in the bacteria. The lichen are artificially grouped together according to form rather than phylogeny. Perhaps the most artificial classification system was employed by mycologists who classified fungal groups on the basis of their sexual spores. Those taxa which had lost the ability to undergo sexual reproduction, even though they were clearly related those that did produce sexual spores, were cast in a phylum called the Fungi Imperfecti or Deuteromycota.

Paraphyletic: Paraphyletic taxa have a common ancestor but do not include all of the descendants. Many useful taxa still are paraphyletic. For example, because all tetrapods are descended from lobe-finned fishes, which also are bony fishes, would require, if cladistic rules are applied stridently, that all mammals, birds, “reptiles”, and amphibians be classified within the bony fishes.
TAXONOMYNSYSTEMATICSPronunciation:ta-KSO-na-mi

Etymology: Taxonomy is derived from two Greek roots that mean tidiness (taxis, τάξις) and a law or principle (nomos, νόμος). Linnaeus (1812) defined taxonomy (names of taxa) to mean the ordered arrangement of living things.

Taxonomy (n.) is the technical process of naming things. Linnaean Taxonomy is hierarchical with nested taxa: kingdom, phylum, class, order, family, genus, species. They can have sub and super categories within any one taxon. Linnaeus (1812) defined taxonomy (names of taxa) to mean the ordered arrangement of living things.

A more recent trend in taxonomy is the PhyloCode, a clade-based taxonomic system which seeks to move away from the rank-based code of Linnaeus. According to the The International Code of Phylogenetic Nomenclature (http://www.ohiou.edu/phylocode/preface.html), “The PhyloCode extends ‘tree-thinking’ to biological nomenclature.”
TELIUM (TELIA)NFUNGIPronunciation:

Etymology:

Group of cells that produce teliospores in rusts.
TELIOSPORENFUNGIPronunciation:

Etymology:

Thick-walled spores produced by rust fungi.

Pronunciation:

Etymology:

Thick-walled spores produced by rust fungi.
TELSONNANIMALSPronunciation:

Etymology:

A telson is the terminal segment of some crustaceans, certain chelicerates, and some hexapods.
TEPALNPLANTSPronunciation:

Etymology:

One of the petals or sepals of a flower in which the perianth segments closely resemble each other.
TESTNPROTISTSPronunciation:

Etymology:

A test is an external covering that is secreted or constructed by secretions from the cell. I distinguish it from a cell wall in that a test is not appressed to the plasmalemma. In fact, sometimes the cell can leave the test entirely.
TESTESNPronunciation:

Etymology:

Testes (testis, sing.) is the male animal gonad. It produces sperm.
TETRASPORENPLANTSPronunciation:

Etymology:

Tetraspores are meiospores produced by certain red algae, especially those that exhibit isomorphic alternation of generation.
TETRASPOROPHYTENPLANTSPronunciation:

Etymology:

A tetrasporophyte is a certain type of sporophyte in red algae that exhibit isomorphic alternation of generation. The tetraspores (actually meiospores) produced by the tetrasporophyte were named before the demonstration of a sexual life cycle in the red algae.
THALLUS (THALLI)NPLANTS, PROTISTSPronunciation:

Etymology:

(1) Thallus or leaf-shaped.

(2) The flat, sheet-like gametophyte of non-vascular embryophytes.
THECA (THECAE)NPROTISTSPronunciation:

Etymology:

A theca (also called an amphiesma) is the name of the dinoflagellate pellicle (formed by the alveolar structure of the cell covering. Cells may be naked (gymnodinoid) or “armored”. Armored dinoflagellates have alveoli that contain cellulosic plates.
THERMOPHILEADJECOLOGYPronunciation:

Etymology:

Thermophiles are organisms (usually bacteria) that have thermal optima of 45C or higher.
THIGMOTACTIC CILIUM (THIGMOTACTIC CILIA)NPPROTISTSPronunciation:

Etymology:

Thigmotactic cilia are ciliary structures that are sensitive to touch and thus function as holdfasts, etc.
THYLAKOIDNPLANTS, PROTISTS, BACTERIAPronunciation:

Etymology:

Thylakoids are membranes, usually stacked, on which the photosynthetic pigments and enzymes are located.
TINSEL FLAGELLUM (TINSEL FLAGELLA)NPPROTISTSPronunciation:

Etymology:

A tinsel flagellum is one that is covered with flagellar hairs and thus appears thicker in light microscopy. Usually, tinsel flagella are anteriorally-directed.
TOGA (TOGAE)NBACTERIAPronunciation:

Etymology:

A toga is a specialized membrane-like outer cell covering that occurs in the Thermotogae. This does not seem to be homologous to the outer membranes of Gram negative bacteria.
TORNARIA LARVA (TORNARIA LARVAE)NPANIMALSPronunciation:

Etymology:

A tornaria larva is a characteristic larval form of hemichordates. It is planktonic, transparent, and long-lived.
TRACHEA (TRACHEAE OR TRACHEAS)NANIMALSPronunciation:

Etymology:

Trachea (tracheae, pl.) is the windpipe of vertebrates, the air-filled tubes in most arthropods.
TRACHEIDNPLANTSPronunciation:

Etymology:

Tracheids are water-conducting cells that have rings of thickened wall.
TRAILING FLAGELLUM (TRAILING FLAGELLA)NPPLANTS, PROTISTSPronunciation:

Etymology:

A trailing flagellum lies away from the direction of the cellular motion. The interpretation is that the flagellum functions by pushing the cell.
TRAMANFUNGIPronunciation:

Etymology:

Inner core of interwoven hyphae in the gills of agaric fungi.
TREE LENGTHNPSYSTEMATICSPronunciation and Etymology: The phrase is made from two common English words.

The tree length is a calculation of the total number of character state changes in a cladogram.
TRICHOCYSTNPROTISTSPronunciation:

Etymology:

Trichocysts are extrusosomes that also are characteristic of the ciliates and dinoflagellates. They can discharge and serve almost as an organelle equivalent to the nematocyst. However, their particular functions have yet to be defined to my satisfaction.
TRICHOGYNENPLANTS, FUNGIPronunciation:

Etymology:

A trichogyne is a thread-like extension of the carpogonium (oogonium) in the red algae. A similar structure occurs in certain ascomycete fungi.
TRICHOSPORENFUNGIPronunciation:

Etymology:

Deciduous sporangia containing a single spore; produced by trichomycetes (parasites of arthropod guts).
TRIPARTITE TUBULAR HAIRNPPROTISTSPronunciation:

Etymology:

Tripartite Tubular Hairs are mastigonemes (flagellar hairs) that occur on the anteriorly-directed flagellum. They seem to reverse the thrust of the flagellum.
TRIRAMOUSADJANIMALSPronunciation:

Etymology:

Triramous (adj.) means three-branched.
TRISULCATEADJPLANTSPronunciation:

Etymology:

A pollen grain with three grooves or furrows.
T-RNANPANIMALS, PLANTS, PROTISTS, FUNGI, BACTERIAPronunciation:

Etymology:

Transfer RNA (t-RNA) is an amino acid carrier that associates with mRNA on a Ribosome in the construction of proteins.
TROCHAL DISKNPANIMALSPronunciation:

Etymology:

The trochal disks are the paired coronas at the anterior ends of Rotifers.
TROCHOPHORE LARVA (TROCHOPHORE LARVAE)NPANIMALSClick here
TROPHI (THIS IS A PLURAL NOUN; THERE IS NO SINGULAR FORM)NANIMALSPronunciation:

Etymology:

Trophi are jaw-like structures of the pharynx (called mastax in rotifers) of Rotifers.
TROPHOZOITENPROTISTSPronunciation:

Etymology:

Trophozoite is the feeding stage, usually of a unicellular parasite.
TRUE BRANCHINGNPPLANTS, PROTISTS, FUNGI, BACTERIAPronunciation:

Etymology:

True branching occurs in filamentous taxa which generally divide in a plane perpendicular to the axis of the filament (thus forming the filament). However, they sometimes divide in a plane parallel to the axis of the filament and form a branch.
TRUE INDUSIUM (TRUE INDUSIA)NPPLANTSPronunciation:

Etymology:

A true indusium is an umbrella-like structure that covers the sporangia of a sorus. The covering is produced by an extention of the sorus itself.
TUBE CELLNPPLANTSPronunciation:

Etymology:

A tube cell develops as part of the microgametophyte within the pollen grain. The tube cell directs the growth and development of the pollen tube, which carries the sperm to the egg in an ovule.
TUBE FOOTNPANIMALSPronunciation:

Etymology:

Tube feet are extentions of the surface of echinoderms. They usually function in attachment and locomotion. They may also function as respiratory and sensory structures.
TUBULAR CRISTA (TUBULAR CRISTAE)NPANIMALS, PROTISTSPronunciation:

Etymology:

Mitochondrial cristae that form as extended saccate structures or tubes are called tubular cristae.
TWO-RANKEDNPPLANTSPronunciation:

Etymology:

Two-ranked means that leaves emerge from the stem on two sides of the stem only. This does not mean that the leaves are opposite (a condition in which two leaves emerge at each node). Example, grasses are two-ranked.
TYPHLOSOLENANIMALSPronunciation:

Etymology:

The trochophore is a fold into the lumen of the annelid gut and serves to increase the absorptive area of the gut wall.
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