Glossary - general
[ A B C D E F G H I J K L M N O P Q R S T U V W X Z ]
Tangential bands (of axial parenchyma) – situated tangentially (close to) the vascular tissue
Tannin granules – hard dark brown granular inclusions found in some cells
Tapering – gradually narrowing
Tapetal – relating to tapetum
Tapetum – innermost layer of cells of the microsporangium (pollen sac) wall that nourish the developing pollen grains
Tap root – the primary root, going straight down
Tardily – slowly, reluctantly
Tectate pollen grain – provided with tectum
Tectum (of pollen grains) – tegillum; the layer of sexine, which forms a roof over the columellae, granules or other infratectal elements
Teeth (of dentate, serrate and crenate leaf margins) – small regular protuberances
Tegmen (of seed) – the inner coat of the seed, in bitegmic species formed from the inner integument; part of the seed coat which develops from the inner integument
Tegula – (Orchidaceae) a stalk to which the pollinia are attached; tegula is derived from the epidermis of the rostellum
Tendril – terminal slender coiling structure derived from branch, leaf or inflorescence, used in climbing
Tension wood – reaction wood in hardwood angiosperms; formed above the affected part of the plant, pulling against the strain; tension wood is composed almost entirely of cellulose (rendering the wood prone to shrinkage)
Tenuinucellar ovule, tenuinucellate ovule – with a thin megasporangium (nucellus with only an epidermal cell layer outside the meiocyte) up to megagametophyte formation; the archesporial cell develops directly into a megaspore cell without formation of a megasporangium; no parietal cells are present between the megagametophyte and the epidermis of the ovule – Opposite: crassinucellar
Tenuous – thin, narrowed, weak, fine
Tepal – division of the perianth, i.e. a sepal or petal, used especially when the distinction between petal and sepal is unclear
Tepal nectary – perigonal nectary; nectary situated on a tepal
Tepaloid stamen – a stamen with a shape similar to a tepal
Terete – circular in cross-section, usually of a cylindrical structure without grooves or ridges
Terminal – at apex of part under discussion; (of inflorescence) terminating the axis, as opposed to axillary
Ternate – (1) arranged in a whorl or cluster of three; (2) ternate-trifoliolate
Ternate-pinnate – when three pinnate leaflets are borne at the summit of the main petiole
Ternate-trifoliolate – with three leaflets attached to one point
Ternatisect (of a two dimensional structure) – divided in three almost to the base
Terrestrial – on land, i.e., not in water
Tertiary – (1) (adjective) third-order, one order down from secondary; (2) (noun) (pl. tertiaries, used in Araliaceae) lateral branches of the main branches
Tesselated surface – with markings in squares or rectangles
Tesselated venation – with a distinct midvein and numerous longitudinal and transverse secondary veins, forming a patterns of squares and rectangles
Testa (of seed) – the outer coat of the seed, in bitegmic species formed from the outer integument; part of the seed coat which develops from the outer integument
Testal – adjective for testa
Tetra- – four-
Tetracolpate pollen grain – with four colpi
Tetracyclic flower – with four whorls (series) of floral parts (sepals, petals and stamens)
Tetracytic stomata – surrounded by four subsidiary cells, two of which are parallel to and two (often smaller) at right angles to the long axis of the guard cells; guard cells surrounded by four regularly arranged subsidiary cells
Tetrad (of pollen grains) – group of four pollen grains formed from a single microsporocyte (pollen mother cell) that are released from the anther as one unit
Tetradynamous – with four long and two short stamens, as in many Brassicoideae
Tetragonal – with four angles in cross-section
Tetragonal tetrad – the cells (e.g. pollen grains) in the tetrad are equidistant and in one plane
Tetrahedral tetrad – the cells (i.a. pollen grains) in the tetrad are equidistant and at the four points of a tetrahedron
Tetrahedriform – shaped like a tetrahedron, with four faces; pyramidal
Tetramerous flower – with the constituent parts in whorls of four
Tetrasporangiate anther – four-celled; with four microsporangia
Tetrasporic megagametophyte – developing from all four megaspore nuclei from the megaspore tetrad
Textured – the way a structure feels to the touch
T-hair – T-shaped unicellular or multicellular hair (as seen from the side)
Thalloid – in the form of a thallus, a vegetative body without differentiation into stem and leaf (in, i.a., Podostemaceae)
Thallus – vegetative tissue, not clearly divided into stem and leaf (as in Lemna)
Theca (pl. thecae) – the locule(s), usually two, of an anther
Theoid leaf tooth – with the medial vein ending in an expanded and opaquely congested apex, not associated with lateral veins
Thorn – short pointed woody structure derived from a reduced branch
Throat (of tubular flowers) – (1) part where the corolla tube widens into the mouth; (2) the apical part of the corolla tube immediately below th mouth (in, e.g., Rubiaceae)
Thrum-eyed (of dimorphic flowers) – the short-styled flower with only the stamens visible in the corolla throat – Opposite: pin-eyed
Thyrse – (1) open inflorescence with a racemose primary branching and not terminated by a flower; a mixed inflorescence with the main axis a raceme and secondary (lateral) axes in the form of cymes; (2) a compact panicle of more or less cylindrical form
Thyrsoid inflorescence, thyrsiform inflorescence – closed inflorescence with a racemose primary branching and cymose secondary (lateral) axes and terminated by a flower;
Tile cells – radial files of dead, empty, erect cells in vascular rays, much narrower radially than the procumbent cells of the ray and interspersed among them; in the Durio type of tile cells the radial files of dead, empty, erect cells in vascular rays are about the same height as the procumbent cells of the ray; in the Pterospermum type of tile cells the radial files of dead, empty, erect cells in vascular rays are two to several times higher than the procumbent cells of the ray
Tilosome – (Orchidaceae) cell of innermost layer of velamen with complex, often lignified, wall processes bordering on passage cells of exodermis
Tomentellous – shortly tomentose
Tomentose – densely covered in short soft hairs, these somewhat curly and matted
Tomentulose – delicately tomentose, somewhat tomentose
Tomentum – a felt-like covering of downy hairs
Tooth – small pointed projection, usually triangular
Toroid (three-dimensional shape) – in the shape of a torus, a ring-shaped cylinder
Torulose – cylindrical with contractions or swellings at intervals
Torus – (1) a ring-shaped cylinder; (2) the receptacle of a flower; the term is usually employed when part of the receptacle is swollen into a distinct cushion, as in many Ochnaceae
Torus (of bordered pits) – a thickening of the primary wall material in the central part of the pit membrane inside the margo
Trabeculate – having the appearance of minute girders
Tracheary element – general term for any water-conducting cell in the xylem (e.g. tracheids and vessel members)
Tracheid – a capillary tube formed from a series of dead cells in the xylem, or a single such cell, water-conducting and fairly broad, in which at least the primary cell wall of the end walls remains intact
Tracheoidal tegmen – tegmen containing tracheary elements
Trailer – prostrate plant that does not root; also (less correctly) plant with long branches hanging down from trees
Trailing habit – prostrate on the ground, but without rooting
Transfer cells – metabolically very active companion cells with few plasmodesmata and numerous labyrinthine intrusions of the their walls; intermediary cells have numerous plasmodesmata which branch in the outer part of the cell walls adjacent to the bundle sheath cells
Transitional lateral wall pitting – a scalariform-like pattern in which some long pits extend the full width of a vessel face, whereas other pits are much shorter two or three pits replacing a long one
Translator – (Asclepiadoideae) the narrow connecting structure between pollinia, which is derived from stigmatic secretions connecting the corpusculum with the pollinia
Transseptal vascular bundles – the vascular bundles to the ovules in a completely syncarpous gynoecium, which do not run up the ovary in the axial tissue, but are found in the ovary wall, curving over at the apex and finally supplying the ovules
Transverse – (1) at right angles to another organ; (2) (of anthers) used for anther opening when the slits are at right angles to the longitudinal axis of the anther; also called explanate
Transversely – lying crosswise, at right angles
Trapeziform (of a plane shape) – with four sides, two of which are parallel
Tree – perennial woody plant with secondary thickening, with a clear main trunk; the distinction between tree and shrub is fluid, but generally accepted to be dependent on the single trunk, and on height, a tree being at least two or three metres tall
Triad – (1) (Poaceae) used for groups of three spikelets; (2) (Arecaceae) group of three florets, the central female, the flanking ones male; (3) (Amaranthaceae) a cluster of three flowwers, a fertile one flanked by two sterile ones
Triarch stele – with three xylem strands
Tricarinate – with three keels
Trichoblast – a specialized cell in the rhizoderm that develops into a root hair
Trichome – hair, bristle or scale
Trichome hydathode – specialized multicellular hairs, which secrete water from the plant
Trichosclereids – type of branched sclereid, with hair-like branches extending into intercellular spaces
Trichotomosulcate pollen grain – with a three-armed sulcus
Trichotomous – three-forked, branched into three
Tricolpate pollen grain – with three colpi
Tricolporate pollen grain – with three compound apertures with pores in furrows
Tricolporoidate pollen grain – with three colpi having indistinct ora
Tricuspidate – with three short sharp points
Tricytic stomata – the guard cells are surrounded by three subsidiary cells which resemble the normal epidermal cells
Trifid – split in three
Trifoliate – with three leaves
Trifoliolate – with three leaflets
Trigonous – obtusely three-angled
Triheterostylous species – with flowers of three types, having styles of three different lengths and often anthers on three different levels
Trilacunar node – with three leaf gaps left in the central vascular cylinder when corresponding numbers of leaf traces depart
Trilobate – with three lobes
Trimerous – in threes (e.g. of a flower with three sepals and three petals, etc.)
Trinucleate pollen grain – pollen grain containing three nuclei (cells), although the number of nuclei may vary among pollen grains of the same individual; trinucleate condition is often associated with gametophytic incompatibility systems
Trioecious – with male, female and hermaphrodite flowers on three separate plants
Tripartite – divided into three parts; consisting of three parts
Triplicate – in three
Triplostemonous androecium – with the number of stamens three times the number of tepals in the nearest perianth whorl
Triporate pollen grain – with three pores
Tripororate pollen grain – with three compound pores
Triquetrous – with three sharp angles
Triradiate – with three arms
Tristichous – arranged one above the other in three vertical rows
Trisulcate pollen grain – with three sulci
Tritegmic ovule – with three integuments (e.g. in Annonaceae)
Trizonocolpate pollen grain – having three colpi (groove-like apertures) aligned longitudinally, equidistant around the equator
Trochlea – (Passifloraceae) ring on the androgynophore
Trullate, trulliform – shaped like a brick-layers’ trowel
Truncate – ending abruptly in a more or less straight line, as if cut off
Trunk – the main axis of a tree, from the roots to where the crown branches; the base, plus the bole, plus the axis of the crown
Tuber – (1) a thickened branch of an underground stem, serving as storage organ, distinguished by bearing axillary buds (stem tuber); (2) a swollen root or branch of a root acting as a reserve store of nourishment or water (root tuber)
Tubercle – (1) a little tuber; used for any small growth (hypothetically) associated with symbiotic organisms; (2) a little protuberance
Tubercular – covered with knobbly or warty protuberances
Tuberculate – covered with wart-like protuberances or knobs
Tuberculate tectum (of pollen grains) – with knobbly projections
Tuberous root or stem – fleshy, swollen
Tubiform – shaped like a tube or cylinder
Tubular – cylindrical and hollow
Tubuliferopunctate tectum (of pollen grains) – with tubuli (small channels through the nexine)
Tuft domatia – resembling tufts of hairs, as in some Rubiaceae
Tufted – growing in right groups, e.g. of leafy stems, the bases of the individual plants touching; caespitose, clumped, tussocky
Tumid – inflated, swollen
Tunic – (1) coat of a bulb, consisting of dead leaf bases; (2) any loose membranous skin not formed by epidermis
Tunica (of root apex) – one or more outer layers which divide only anticlinally
Tunica-corpus construction – the apical meristematic region is differentiated into one or several outer peripheral layers, the tunica, with usually anticlinal cell divisions, and an inner cell mass, the corpus, with mostly periclinal cell divisions
Tunicated bulb – a bulb covered with complete enveloping coats, as in an onion
Turbinate – top-shaped, obconical and narrowed towards the apex (point)
Turgescent – becoming turgid on inflated
Turgid – swollen
Turion – (1) detachable vegetative buds; (2) a scaly sucker or shoot from the ground, as in Asparagus; (3) resting bud; bud resting during adverse season
Tussock – compact clump of grasses or grass-like plants
Tussock grass – grass growing in compact clumps
Twig – a small branch or shoot; more precisely, the current year’s shoot
Twiner (of a climber) – supporting itself by the stems (less often petiole or inflorescence) coiling around a structure or another plant
Twining plant or organ – coiling around a structure or another plant
Tyloses (of vascular tissue) – outgrowth from adjacent parenchymatous cells through a pit cavity in a vessel wall, more or less blocking the lumen