Based on the glossary in Dransfield, J., N.W. Uhl, C.B. Asmussen-Lange, W.J. Baker, M.M. Harley & C.E. Lewis. 2008. Genera Palmarum - Evolution and Classification of the Palms. Royal Botanic Gardens, Kew.
All images copyright of the artists and photographers (see images for credits).
Abaxial — the side of an organ that faces away from the axis which bears it, e.g., the under surface of a leaf, the lower surface of the petiole, or the outer surface of a tubular bract.
Abscission — separation, often by a distinct layer.
Acanthophyll — a spine, often large, derived from a leaflet.
Acaulescent — lacking a visible stem.
Acervulus — a group of flowers borne in a line.
Acetolysis/acetolyse — a process that is used to clear pollen grains of their internal cellular fraction, the intine, and any external lipidic coatings. The acetolysis mixture comprises nine parts acetic anhydride and one part sulphuric acid.
Acropetal — toward the apex.
Acuminate — tapering to a point.
Acute — distinctly and sharply pointed but not drawn out.
Adaxial — the side of an organ towards the axis that bears it; e.g., the upper side of a leaf, the upper surface of a petiole, or the inner surface of a tubular bract.
Adjacent-ligular —in germination, the new shoot developing next to the seed and enclosed by a ligule.
Adnate — attached to, usually of one kind of organ to another kind, as bract to axis.
AFLP — amplified fragment length polymorphism, a type of DNA data used to study relationships among populations or species.
Anastomose — to unite, usually forming a network.
Anatropous — an ovule bent parallel to its stalk so that the micropyle is adjacent to the hilum.
Androecium — collective term for the stamens.
Anther — the part of a stamen that contains the pollen, usually two-chambered.
Anthesis — time of flower opening, when the flower is ready for fertilisation, i.e., shedding of pollen or receptivity of stigma.
Aperture — see ‘Germinal aperture’.
Apiculate — bearing a short, sharp but not stiff point.
Apocarpous — with free carpels.
Aril — an outgrowth of the stalk of the ovule, sometimes resembling a third integument.
Armed — bearing some form of spines.
Asymmetric/asymmetrical — without symmetry.
Auricle — an ear-like lobe.
Axillary — borne in an axil, which is the angle between the stem and the leaf or another organ that arises from the stem, such as a bract.
Basifixed — attached by the base.
Basipetal — developing from the apex toward the base.
Bicarinate — having two keels.
Bifid — divided in two, usually equal, parts.
Bijugate — used for a pinnate leaf with two pairs of leaflets.
Bipinnate — doubly pinnate.
Bi-symmetric/bi-symmetrical — with two planes of symmetry.
Bootstrap support — an estimate of confidence in an individual clade within a phylogenetic tree. High bootstrap support indicates a high level of confidence that the clade will be resolved as new data are analysed. Low bootstrap support indicates a possibility that the clade may not be resolved by new data.
Bract — modified leaf associated with the inflorescence.
Figures 1.5 & 1.6 (LTS)
Bracteole — a small bract borne on a flower stalk, often present even when the flower is essentially sessile.
Bremer support — a measurement of the reliability of an individual clade with respect to alternative hypotheses. Bremer support is negatively affected by conflict in a dataset, decreasing when alternative hypotheses are nearly as good as the best hypothesis.
Brevisulcate — of a pollen grain having a very short sulcus.
Caducous — dropping off early or gradually.
Caespitose — clustered.
Callose envelope — callose is a structural polysaccharide found in higher plants. It has a blocking function — in the early stages of pollen development, a thick layer of callose is deposited around each pollen mother cell (meiocyte) separating them from each other.
Calyx — the outermost or lower-most whorl of floral organs, the sepals.
Campylotropous — an ovule curved with the micropyle close to the hilum and the embryo sac also curved.
Capitate — head-like; in pollen, of columellae with expanded apices.
Carpel — the single unit of the gynoecium.
Catkin-like - used to describe a cylindrical rachilla resulting when flowers are densely crowded.
Chartaceous - paper-like, thin and stiff.
Ciliate - bearing a fringe of hairs.
Cincinnus - a flower cluster wherein each successive flower arises in the axil of a bracteole borne on the stalk of the previous flower.
Cirrate - bearing a cirrus.
Cirrus - a climbing organ, structurally a whip-like extension of the leaf rachis, armed with reflexed spines and/or acanthophylls, cf. flagellum.
Clade - a monophyletic group. A branch on a phylogenetic tree.
Clava/clavae/clavate - a club-shaped element of the ectexine that is higher than 1 μm, with a diameter smaller than height and thicker at the apex than the base.
Clustered - with several stems.
Columella/columellae - a rod-like element of the ectexine supporting the tectum.
Columellar layer - synonym of infratectum.
Concolorous - when two surfaces (usually leaves) are of the same colour.
Connate — united, used when organs of the same kind are joined, as sepals connate; see ‘tubular calyx’.
Connective —the part of a stamen that connects the anthers, usually distinct from the filament.
Consensus tree — a phylogenetic tree that summarises more than one hypothesis of relationships. A strict consensus tree only includes clades that are found in all hypotheses.
Coriaceous — leathery.
Corolla — the second whorl of flower organs, the petals, inside or above the calyx.
Cortex — the ground tissue between the vascular cylinder and the epidermis.
Costa — a rib, when single, the midrib or vein.
Costapalmate — shaped like the palm of a hand and having a short midrib or costa.
Crenulate — shallowly scalloped or bearing rounded teeth.
Crotonoid — a characteristic type of ectexine ornamentation comprising rings of five or six (sometimes more) raised, often triangular, elements arranged around a circular area, usually formed by capitate columellae.
Crown — the cluster of leaves borne at the tip of the stem.
Crownshaft —a conspicuous cylinder formed by tubular leaf sheaths at the top of the stem.
Cupule — a small cup-like structure.
Cuticle — a layer of wax covering the epidermis.
Cytokinesis — the process of cytoplasmic division.
Deciduous — shed periodically, falling.
Decumbent — reclining, but with the apex or tip ascending.
Decussate tetrad — a multi-planar tetrad of pollen grains or spores arranged in two pairs lying across one another, more or less at right angles.
Deltoid — shaped like an equilateral triangle.
Dentate — toothed.
Determinate — bearing a terminal organ, as in an inflorescence when a branch ends in a flower bud.
Dichotomous (stem) — equally forking.
Didymous — of anthers where the connective is almost absent.
Digitate — like fingers.
Dimorphic — with two different forms.
Dioecious — when staminate and pistillate flowers are borne on different plants.
Diporate — of a pollen grain having two pori (germinal apertures).
Discolorous — when two surfaces (usually leaves) are of a different colour. (c.f. concolorous)
Distal — farthest from the place of attachment; in pollen, applied to features of the mature pollen grain that face outward during the tetrad stage.
Distal disulcate — of a pollen grain with paired sulci lying parallel to the long axis of the pollen grain on the distal face.
Distant — widely separated.
Distichous — arranged in two ranks.
Disulcate — of a pollen grain having two sulci (germinal apertures). In palms, usually positioned on the short equatorial faces of the pollen grain but see also ‘distal disulcate’.
Divaricate — spread widely.
Dorsifixed — attached by the abaxial (usually outer) side.
Dyad — a pair.
Ectexine — the outer layer of the pollen exine, in TEM, it has higher electron density than endexine.
Elliptic — oblong with regularly rounded ends.
Emarginate — with a notch cut out, often at the apex.
Embryo — the rudimentary plant present in a seed.
Endexine — the inner layer of the pollen exine, it has lower electron density than ectexine.
Endocarp — the innermost layer of the fruit wall.
Endosperm - in palms, the nutritive body of a seed.
Entire (leaf) - undivided.
Eophyll - in a seedling, the first leaf having a blade.
Epicarp - the outermost layer of the fruit wall.
Epipetalous - united with, often appearing to be borne on, the petals.
Equator/equatorial - the dividing line between the distal and proximal faces of a pollen grain or spore.
Exine - the outer usually sporopollenin layer of a pollen grain, which has an important protective function during pollen transfer from anther to stigma.
Exposed columellae - columellae not overlain by a tectum, usually in the form of spines or clavae in intectate pollen.
Extended sulcate - of a pollen grain having a single sulcus, the apices of which extend beyond the equator towards the proximal face.
Extrorse - of anthers, opening abaxially, away from the centre of the flower.
Fenestrate - with holes or openings, sometimes like windows.
Fibrous - composed of or including fibres.
Filament - of a stamen, the stalk which bears the anther.
Filamentous - thread-like.
Flabellate - fan-shaped or wedge-shaped.
Flagellum - a whip-like climbing organ derived from an inflorescence, bearing reflexed spines, cf. ‘cirrus'.
Floccose - bearing soft, uneven hairs or scales.
Foot layer - the inner layer of the ectexine.
Foveola/foveolae/foveolate - large rounded holes or depressions (lumina) in or through the tectum, which are too large to be described as perforations (>1 μm in diameter), separated by broad areas of tectum similar in width, or wider than, the foveolae.
Funiculus - the stalk of an ovule.
Gamo - as a prefix, united or fused (see sepals and petals).
Gemma/gemmae/gemmate - sexine elements that are constricted at the base, higher than 1 μm, and approximately the same width as height.
Germinal aperture - the functional opening, covered by an aperture membrane in vivo, through which the pollen tube emerges (in palms a sulcus or pore).
Gibbous - more convex on one side than another, as a not quite full moon.
Glabrous - smooth, lacking hairs, scales or other indument.
Glaucous - covered with a bluish gray or greenish bloom.
Glomerule - a knob-like cluster of flowers (such as in Livistona spp.).
Granulae/granular - general word for small rounded elements.
Grapnel - a small anchor or hook with three or more flukes.
Gynoecium - the ovule-bearing organ of the flower, composed of one to several carpels and divisible into an ovary, a style, and one or several stigmas.
Hapaxanthic - describing shoots that flower then die, cf. ‘pleonanthic'.
Haploid - a nucleus or individual containing only one representative of each chromosome of the chromosome complement.
Hastula - a flap of tissue borne at the insertion of the blade on the petiole on the upper, lower, or both leaf surfaces.
Hemianatropous - an ovule turned so that the micropyle is at right angles to its stalk (funiculus).
Hermaphrodite - flowers having both stamens and gynoecium.
Heteropolar - pollen grains or spores where the distal and proximal faces differ; for example, in the monosulcate pollen grains of palms.
Hilum - the scar left on the seed where it was attached.
Homogeneous - uniform, the same throughout.
Imbricate - overlapping, cf. ‘valvate'.
Imparipinnate - unevenly pinnate, bearing a terminal leaflet.
Impression mark - a mark on the proximal face of the pollen grain retained from the post-meiotic stage. This mark can be linear from tetragonal or decussate tetrads or Y-shaped from tetrahedral tetrads.
Inaperturate - without a germinal aperture.
Incomplete equatorial - of a pollen grain having a very elongated (extended) sulcus, extending almost completely around the equator so that the apices all but meet.
Indeterminate - not bearing a terminal flower or other organ.
Indument - any covering as hairs or scales.
Induplicate - V-shaped in cross-section, trough-shaped.
Inflexed - bent or curved inward toward the centre.
Inflorescence - the branch that bears the flowers, including all its bracts and branches.
Figures 1.5 & 1.6 (LTS)
Infrafoliar - borne below the leaves.
Infratectum - a general term for the ectexine layer beneath the tectum, and above the foot layer.
Infructescence - as inflorescence but in fruit.
Intectate - without a tectum but with sculptural elements.
Integument - a covering or envelope enclosing the ovule.
Interfoliar - borne among the leaves.
Internal cellular fraction - the internal part of the pollen grain including the generative and vegetative cells and surrounding cytoplasm and organelles.
Internode - the space or part of a stem between the attachments of two leaves.
Interrupted reticulum/reticulate - a reticulum where the muri are not continuous, as in a net, but appear ‘broken up' or fragmented.
Intersegmental fibres - fibres resulting from disintegration of the ribs between the segments of palmate leaves.
Intine - the inner layer, of the pollen grain wall (‘sporoderm'), which has an important protective function during pollen germination and pollen tube growth.
Introrse - of anthers, opening toward the centre of the flower.
Jacknife support - an estimate of confidence in an individual clade within a phylogenetic tree. See Bootstrap support for interpretation of support values.
Lamellae/lamellar - a general term for a thin layer - in palm pollen, these layers refer to a lamellated foot layer as in Calamoideae, they are unusual elsewhere in the family.
Lamina - blade.
Lanceolate - narrow, tapering at both ends, the basal end often broader.
Latrorse - of anthers, opening lateral to the filament.
Leaflets - divisions of pinnate leaves.
Ligule - a distal projection of the leaf sheath.
Linear - several times longer than wide, usually narrow.
Linear impression mark - a mark on the proximal face of the pollen grain retained from the post-meiotic stage of tetragonal or decussate tetrad.
Lipid-based coatings - ‘pollenkitt'/'pollen coat' - sticky material produced by the tapetum that is considered to have a range of probable functions.
Locule - the cavity in which the ovule is borne.
Long axis - the widest dimension of the pollen grain, particularly used for heteropolar pollen.
Lumina/lumen - the space(s) enclosed/surrounded by the muri in a reticulate ectexine.
Marcescent - withering before being shed.
Maximum likelihood - a criterion for choosing among different hypotheses of relationships, favouring the hypothesis that best fits a defined model of evolution.
Medifixed - attached at the middle.
Meridional/meridionally - describing longitudinal features on a pollen grain or spore oriented perpendicular to the equator.
Meristem - the growing region of a plant, a special area of undifferentiated cells wherein new cells and organs are developed.
Mesocarp - the middle layer of the fruit wall.
Micro-channels - small channels in the tectum that penetrate to the infratectum.
Micro-fossulae - channel-like indentations in the tectum that do not penetrate to the infratectum.
Micropyle - an aperture through the integuments of the ovule.
Microsatellites - regions of repetitive DNA that are highly variable and useful for genetic analyses of populations or species.
Microsporogenesis - in pollen, the development from the sporogenous tissue of the anther to maturity as (usually) individual pollen grains.
Mitochondrial DNA - DNA within mitochondria, which are organelles found inside the cells of plants and many other kinds of organisms.
Moderate - medium or intermediate in size.
Monocarpic - fruiting once, then dying completely.
Monoecious - describing a plant bearing both staminate and pistillate flowers.
Monomerous - formed of a single member.
Monophyletic group - a taxonomic group that includes all descendants of a common ancestor. A branch on a phylogenetic tree. Monophyletic groups are the basis of modern, phylogenetic classifications.
Monopodial - with a single main axis.
Monoporate - of a pollen grain, having a single, presumed distal, pore (germinal aperture).
Monosulcate - of a pollen grain, having a single sulcus (germinal aperture).
Morphology/morphological - the study of form, particularly of external structures - the introduction of the word is attributed to the poet and botanist Johann Wolfgang von Goethe.
Muri/murus - a continuous ridge that separates the lumina of a reticulate ectexine.
Node - the area of a stem where a leaf is attached.
Nuclear DNA - the majority of DNA found in plant cells, located within the nucleus.
Nucleotide substitution - a mutation that replaces one nucleotide in a segment of DNA with another. When present in more than one taxon, these mutations may provide evidence of phylogenetic relationship.
Oblate - ± spherical but flattened at the poles; of pollen, a rather flattened spheroidal or trianguloid pollen grain.
Obovoid - egg-shaped, broader distally.
Obpyriform - pear-shaped but attached at the broad end.
Ocrea - an extension of the leaf sheath beyond the petiole insertion.
Ontogeny - the development of an individual through its various stages.
Operculum - a lid or cover; in pollen, a distinctly delimited ectexinous lid-like structure that covers all or part of an aperture.
Orbicule/orbiculae (or Ubisch body) - a distinctive granule, usually orbicular, of sporopollenin produced by the tapetum. These may be deposited on the outer exine of maturing pollen grains.
Order (and its extensions, first, etc.) - a sequence, as of branching: a first-order branch branches to produce a second-order branch, etc.
Orthotropous - an erect ovule with the micropyle distal and hilum basal.
Ovary - the ovule-bearing part of the gynoecium.
Ovoid - egg-shaped.
Ovule - the young or developing seed.
Palman - the undivided central part of a palmate leaf.
Palmate - shaped like the palm of the hand, all ribs or leaflets arising from a central area.
Papillose - bearing nipple-like projections.
Paraphyletic - a taxonomic group that includes some, but not all descendants of a common ancestor.
Paripinnate - evenly pinnate, lacking a terminal leaflet.
Parsimony - a criterion for choosing among different hypotheses of relationships. Parsimony favours the hypothesis that offers the simplest explanation for observed data.
PCR - polymerase chain reaction, a process that allows specific DNA regions to be targeted and copied for many types of genetic analysis, including sequencing.
Pedicel - a floral stalk.
Peduncle - the lower unbranched part of an inflorescence.
Peduncular bracts - empty bracts on the main inflorescence axis between the prophyll and the first rachis bract.
Peltate - round, shield-like, attached in the centre.
Perforate/perforation - in pollen morphology, applied to holes through the tectum of less than 1 μm in diameter.
Perianth - the sepals and the petals together.
Petal - one unit of the inner floral envelope or corolla.
Petiole - the stalk of a leaf.
Phylogeny - a hypothesis of relationships that can be expressed in the form of a branching diagram or tree (phylogenetic tree).
Pinna(e) - a leaflet (leaflets) of a pinnate leaf.
Pinnate - feather-like, lateral ribs or leaflets arising from a central axis.
Pinnule - the leaflet of a bipinnate leaf.
Pistillate - bearing a pistil (gynoecium), the ovule-bearing organ of the flower.
Pistillode - a sterile gynoecium.
Pit - a cavity formed by united bracts, enclosing flowers.
Pith - the parenchymatous or often spongy centre of a stem.
Plastid DNA - DNA within plastids, a class of organelles found in plant cells.
Pleonanthic - describing shoots flowering continuously, not dying after flowering, cf. ‘hapaxanthic'.
Plicate - pleated.
Plumose - softly feathered.
Pneumatophores - Above-ground, ‘breathing' roots that allow gas exchange in habitats with inundated or waterlogged soil.
Podsol - a zoned soil with a layer of humus overlying an acidic, highly leached layer, and a basal layer with iron deposition.
Polar/polarity - the condition of having distinct poles. Polarity of pollen grains is determined by their orientation at tetrad stage or by inference from the distribution of apertures and other features.
Pollen mother cell (PMC) - synonym of microsporocyte or meiocyte: a cell that divides by meiosis to produce haploid pollen or spores.
Pollen viability - the potential of a pollen grain to germinate and fertilise ovules.
Polygamo-dioecious - bearing hermaphrodite and either male or female flowers.
Polyphyletic - a taxonomic group that does not have a single recent common ancestor. Two or more unrelated branches on a phylogenetic tree.
Pontoperculate/pontoperculum - a type of operculum that is not completely isolated from the remainder of the ectexine, but linked to it between the ends of the apertures as in Chamaerops and Iriartella.
Porate - of a pollen grain, having one or more germinal pores.
Poricidal - opening by pores.
Praemorse - jaggedly toothed, as if bitten.
Prophyll - the first bract borne on the inflorescence, usually 2-keeled.
Prostrate - lying flat.
Protandrous - of flowers or inflorescences, pollen shed before the stigma is receptive.
Protogynous - of flowers or inflorescences, the stigma receptive before the pollen is shed.
Proximal - nearest to the attachment, basal; in pollen, applied to features of the mature pollen grain that face inward at tetrad stage.
Pseudomonomerous - appearing to be of one member but actually of several, as a gynoecium with one fertile carpel and one locule but parts of two other carpels present.
Psilate - smooth.
Punctiform - dot-like.
Pyrene - a seed-like body formed by a hard, often sculptured layer of endocarp that surrounds the seed.
Pyriform - pear-shaped.
Rachilla - the branch that bears the flowers.
Rachis - the axis of a leaf beyond the petiole; or the axis of an inflorescence beyond the first branches, i.e., beyond the peduncle.
Rachis bracts - bracts subtending first-order branches of the inflorescence.
Radicle - the first root formed by the embryo.
Ramenta - rather thin scales with ragged edges, often large and irregular in shape.
Rank - a row, usually a vertical one.
Raphe - a ridge or depression on the seed, usually the source of fibrovascular branches.
Raphides - bundles of needle-shaped crystals of calcium oxalate.
Receptacle - the central axis of a flower to which the organs (sepals, petals, stamens, carpels) are attached.
Reduplicate - of leaflets ∧-shaped in cross-section.
Rein - in palms, a narrow marginal strip that is shed when the compound leaf unfolds.
Remote-ligular - in germination, the young plant connected to the seed by a long tubular cotyledonary petiole, bearing a ligule.
Remote-tubular - in germination, the young plant connected to the seed by a long tubular cotyledonary petiole, lacking a ligule.
Resolution - an arrangement of taxa in a phylogenetic tree, e.g., "Tribe Caryoteae is resolved within subfamily Coryphoideae." Also used to indicate the level of ambiguity in a phylogenetic hypothesis, e.g., "Relationships within tribe Areceae are poorly resolved."
Reticulum/reticulate - large rounded or, more frequently, angular holes (lumina) through the tectum. Unlike foveolae, the lumina are separated by areas of tectum (muri) that are narrower than the lumina; the overall appearance is net-like.
RFLP - restriction fragment length polymorphism, a type of DNA data used to study phylogenetic relationships at all taxonomic levels.
Rheophyte - a plant adapted to growing in or on the banks of fast-flowing rivers; leaflets of rheophytic palms are usually very narrow, often linear.
Rhizome - underground stem.
Ribosomal DNA - regions of repetitive DNA that encode structural RNA molecules involved in protein synthesis.
Ring murate - superficially similar to reticulate but each lumen in the tectum (sometimes two or three small lumina together) is surrounded by a discrete ring or loop of tectum pressed against neighbouring rings.
Root boss - a rounded basal protuberance from which lateral roots emerge.
Root spines - spines developed from short roots.
Rugose - wrinkled.
Rugulae/rugulate - in pollen, elongate irregular crumpled/wrinkled elements of the tectum, sometimes with perforations or microfossulae/microchannels between.
Ruminate - darkly streaked due to infolding of the seed coats.
Sagittate - enlarged at the base into two acute, straight lobes like the barbed head of an arrow.
Sarcotesta - a fleshy layer developed (in palms) from the outer seed coat.
Scabrate - (of pollen) roughened or with elements smaller than 1 μm.
Scale leaf - a reduced leaf.
Segment - the division of a palmate or costapalmate leaf.
Semitectate - a partial tectum in which tectal interruptions to the infratectum are wider than the surrounding tectum (e.g., reticulate).
Sepal - a single part of the outermost whorl of floral organs the calyx.
Seral - a temporary or developing vegetation type.
Sessile - lacking a stalk.
Sheath - the lowest part, or the base of the leaf that is always tubular at first but often splits during or after maturity.
Short axis - the shortest dimension of the pollen grain, particularly used for heteropolar pollen.
Sigmoid - S-shaped.
Simultaneous cytokinesis - the dividing cell plates advance centripetally, and all cell plates are formed only after the second meiotic division.
Sinuous - wavy.
Sister group - the closest relative in a phylogenetic tree.
Solitary - single stemmed, not clustering.
Spadix - in palms, the whole inflorescence. Not used because of ambiguities with other families.
Spathe - a large sheathing bract usually either the prophyll or peduncular bract. Not used because of its ambiguity within palms.
Spatulate - shaped like a small spatula, oblong with an extended basal part.
Spicate - spike-like, the inflorescence unbranched, the flowers apparently borne directly on the axis.
Spicule - a very slender brittle, needle-like spine.
Spines/spinulose - used in pollen morphology for long, usually tapering elements; in palm pollen, length is defined as >2 μm.
Spinulae/spinulose - small pointed elements extending from the tectum or foot layer (in intectate pollen); in palm pollen, height is defined as <2 μm.
Spinules - very small spines; in pollen, small pointed elements extending from the foot layer or tectum; in palm pollen, height is defined as <2 μm.
Sporopollenin - the material comprising the tough outer pollen wall of most flowering plants. It comprises carbon, hydrogen and oxygen in an approximate ratio of 4:6:1. Recent results confirm the presence of fatty, aromatic and minimal carboxylic acid components. Although the components are consistent, the ratio of the components is apparently not consistent through all plant groups. Sporopollenin is probably "a randomly cross-linked biomacromolecule without a repetitive large-scale structure" and, furthermore, this is "a characteristic which would inherently make this material resistant to enzymic attack, as well as to many laboratory procedures designed to reduce/return it to its principle components". This being so would account for the extraordinary preservational qualities of pollen exine.
Spur - a short, often curved and tapered projection (such as in Kerriodoxa spp.).
Stamen - the male organ of a flower; a stalk or filament bearing an anther containing pollen.
Staminate - bearing stamens, the pollen bearing organs of a flower.
Staminode - a vestigial stamen often greatly modified in form.
Stem - the main axis.
Stigma - the pollen receptor on the gynoecium, usually distal.
Stilt roots - oblique, lateral roots, often large as in Socratea spp., also called prop roots.
Striate - lined; in pollen, narrow, elongate, closely set and generally parallel elements of the tectum.
Style - the often attenuate part of a carpel or gynoecium between the ovary and the stigma.
Sub - as a prefix, meaning nearly or almost, e.g., subopposite equals nearly opposite.
Subequatorial - (of pollen) below the equatorial line, towards the proximal face.
Subulate - awl-shaped.
Successive cytokinesis - the dividing cell plates extend centrifugally, and the cell plates are formed at the first and second meiotic division, giving a distinct dyad stage.
Sulcate/sulcus/sulci - grooved or furrowed; in pollen, an elongate or slit-like aperture with a distal position, and generally associated monocotyledons. In the calamoid palms, however, there are two sulci positioned on the short equatorial axes of the pollen grain
Sulcus/sulci - an elongate aperture usually situated either at the distal long axis face of the pollen grain or, less commonly, at the equatorial short axes of the pollen grain.
Supratectate - above the tectum: for elements on top of, but attached to, the tectum.
Symmetric - with at least one plane of symmetry.
Sympodial - a stem made of superimposed branches, lacking a single main axis.
Syncarpous -with united carpels.
Tectate - with a tectum.
Tectum - the uppermost layer of the ectexine, usually subtended by an infratectum.
Terete - circular in cross-section, usually cylindrical.
Testa - the outer coat of the seed.
Tetrachotomosulcate/tetrachotomosulcus - of pollen having a four-armed sulcus.
Tetrad - a group of four united pollen grains or spores, either as a developmental stage or as a dispersal unit.
Tetragonal tetrad - a uniplanar tetrad in which all four members are in contact at the centre of the tetrad so that, in correct orientation, the adjacent walls form a cross.
Tetrahedral tetrad - a multiplanar tetrad in which each of the four members is in contact with the other three members, so that the centres of the grains define a tetrahedron.
Thecae - the locules of an anther.
Tomentose -densely covered with short hairs, scales, wool, or down.
Topology - the arrangement of branches on a phylogenetic tree.
Total evidence - a phylogenetic analysis of all available data.
Triad - a special group of two lateral staminate and a central pistillate flower, structurally a short cincinnus.
Trichotomosulcate/trichotomosulcus - of pollen having a three-armed sulcus.
Trijugate - bearing three pairs of leaflets.
Trilocular - having three chambers, each usually bearing an ovule or seed.
Triovulate - gynoecium with three ovules, one in the locule of each carpel.
Triporate - of pollen having three pores.
Truncate - as though cut off nearly straight across.
Tubercles - short, stout, persistent floral stalks, appearing as small humps, in coryphoid palms.
Ultrastructure/ultrastructural - structural details of cells above the limit of resolution of the light microscope, and only revealed by electron microscopy.
Undulate - waved.
Unilocular - with a single cavity.
Uniovulate - with a single ovule.
Urceolae/urceolate - urn-shaped elements situated on the foot layer.
Valvate - meeting exactly without overlapping, cf. ‘imbricate'.
Ventricose - swollen.
Verrucae/verrucate - a wart-like element of ectexine, more than 1 μm wide, broader than it is high and not constricted at the base.
Versatile - of anthers, attached near the centre and movable on the filament.
Zonasulcus/zonasulcate - a ring-like sulcus. Strictly, ‘zonasulcus' equals meridional orientation and ‘zonasulculus' equals equatorial orientation. However, the two words are easily confused by the non-specialist and, frequently the terms ‘meridional zonasulcus/zonasulcate' or ‘equatorial zonasulcus/zonasulcate' are used.