Design and maintenance by Peter Hoen
	Updated April 2010

Part 3 (I-O)

In all drawings, the distal pole is on top, the proximal pole at the bottom, unless otherwise specified.
e = equatorial view, p = polar view; H = high level, L = low level.
The terms printed in bold are preferred.
The colors are according the scheme described in the introduction.
Click on a drawing for a full sized picture.

Impression mark (Harley, 1996)
	A mark on the proximal face of a pollen grain retained from the post-meiotic stage. This mark can be linear from tetragonal tetrads or Y-shaped from tetrahedral tetrads. Examples: Nypa fruticans, Howea belmooreana (Palmae).

In-
	A prefix used to emphasis the absence of a feature, as for example in inaperturate. See also: A-.

Inaperturate (adj.) (Iversen and Troels-Smith, 1950)
	Describing a pollen grain or spore without apertures. Example: Populus (Salicaceae), Taxus (Taxaceae). Comment: The term should be used where apertures are completely absent. If ectoapertures are absent, but endoapertures are present, the pollen is cryptoaperturate. See also: cryptoaperture, omniaperturate.

Incidence (pl. incidences) (Batten and Christopher, 1981)
	A structure formed by the termination of the inner wall layer at the endogerminal which gives rise to a deep V-shaped atrium that points towards the centre of the grain. Example: Pseudotrudopollis. Comment: This term is used in descriptions of the fossil Normapolles group. See also: cuneus.

Infra-
	A prefix meaning below or beneath. Comment: The term is often used for patterns underneath a complete or partial tectum. Examples: infrareticulate, infrarugulate, infrastriate, infrastructure, infratectate. See also: intra-.

Infratectum (pl. infratecta, adj. infratectate) (APLF, 1975)
	A general term for the layer beneath the tectum, which may be alveolar, granular, columellar, or structureless. Synonym of interstitium ( Walker and Walker, 1981).

Infraturma (pl. infraturmae) (Potonié, 1956)
	An artificial grouping of form-genera of spores and pollen in the turma- system of Potonié. See also: anteturma, subturma, turma.

Inner tetrad mark (Gupta and Udar, 1986)
	A tetrad mark at the inner layer of a spore and which does not reach up to the margin when seen in polar view and always smaller than the outer tetrad mark.

Inordinate (adj.) (Iversen and Troels-Smith, 1950)
	Describing a pollen grain or spore with an arrangement of elements irregularly distributed. Antonym: ordinate. Comment: The elements can be of structural or sculptural origin. Examples: columellae under a tectum; scabrae on the tectum.

Insula (pl. insulae, adj. insulate) (Straka, 1964)
	Synonym of areola.

Intectate (adj.) (Iversen and Troels-Smith, 1950)
	Describing pollen grains without a tectum, but with sculpturing. Examples: Viscum (Loranthaceae), Ilex (Araliaceae). See also: atectate, etectate, semitectate, tectum.

Inter-
	A prefix for in between. Comment: In palynology the prefix has been used in many different contexts, from indicating position of apertures to defining areas of the surface.

Interaspidium (pl. interaspidia) (Hoen and Punt, 1989)
	The area of exine between ( aspides. Example: Dorstenia (Moraceae).

Intercolpium (Fægri and Iversen, 1950)
	The meridional segment between two colpi and extending to the poles. Comment: The terms mesocolpium and apocolpium are recommended because they enable a more precise subdivision of the pollen surface. See also: apocolpium, mesocolpium.

Interlacunar gaps (Wodehouse, 1935)
	Gaps in the short sexinous ridges which often divide the ectoapertures of lophate pollen grains into lacunae. Example: Cichorium intybus (Compositae). See also: lophate.

Interlacunar ridges (Wodehouse, 1935)
	Ridges separating the lacunae in lophate pollen grains. Example: Cichorium intybus (Compositae).

Interloculum (pl. interlocula) (Thomson and Pflug, 1953)
	A space between the inner- and outer wall layers that is present around most or all of the pollen grain. Example: Extratriporopollenites conjunctus. Comment: The term was originally used for features in pollen of the Triatrioaperturate category of the fossil Normapolles group.

Internal foramen (pl. internal foramina) (Skvarla and Larson, 1965)
	Foramen present within the sexine/ectexine. See also: foramen.

Internal tectum (Skvarla and Larson, 1965)
	A more or less continuous layer within the outer sexine/ectexine composed of laterally connected parts of columellae. Example: Nigella damascena (Ranunculaceae). Comment: Differs from infratectum and interstitium in being a single layer rather than referring to a number of elements under the tectum.

Interporal lacuna (pl. interporal lacunae) (Wodehouse, 1935)
	A lacuna occurring between the ends of two ectoapertures and adjacent to the polar area of a lophate pollen grain. Example: Tragopogon pratensis (Compositae). See also: lacuna.

Interporium (pl. interporia) (Iversen and Troels-Smith, 1950)
	The meridional segment between two pores extending to the poles. Comment: The terms mesoporium and apoporium are recommended because they enable a more precise subdivision of the pollen surface. See also: apoporium, and mesoporium.

Interradial (adj.) (Couper and Grebe, 1961)
	Referring to areas of the proximal face or the equatorial periphery of trilete spores, lying between the radial arms of the laesurae. Comment: Interradial is also used to indicate the position of apertures with reference to tetrad organisation (Walker and Doyle, 1975).

Interstitium (Walker and Walker, 1981)
	The layer of the exine situated between the nexine and the tectum. Synonym of infratectum.

Intexine (Potonié, 1934)
	Synonym of nexine.

Intine (Fritzsche, 1837)
	The innermost of the major layers of the pollen grain wall underlying the exine and bordering the surface of the cytoplasm. Comment: The intine is not acetolysis resistant and is therefore absent in conventionally prepared palynological material.

Intra-
	A prefix meaning within. See also: infra-.

Intrareticulum (adj. intrareticulate) (Iversen and Troels-Smith, 1950)
	Synonym of infrareticulum.

Isodiametric tetrad
	A general term for tetrads in which all members are more or less the same in size. Antonym: anisodiametric tetrad.

Isopolar (adj.) (Erdtman, 1947)
	Describing a pollen grain or spore in which the proximal and distal faces of the exine are alike. Antonym: heteropolar.

Isospore
	A spore of a plant producing only one kind of spore (Jackson, 1928). See also: miospore.

Isosporous (adj.)
	Describing plants producing only one kind of spore (Jackson, 1928). Synonym of homosporous. Antonym: heterosporous.

Kyrtome (Potonié and Kremp, 1955)
	A more or less arcuate fold or band in the interradial areas outside the (laesurae of trilete spores. Examples: Ahrensisporites guerickei, Concavisporites rugulatus. Comment: Some palynologists prefer to use torus for separate interradial bands, and kyrtome for a connected feature. See also: torus.

Labrum (pl. labra, adj. labrate) (Thomson and Pflug, 1953)
	Protruding part of the exine at the pores of porate pollen grains. Example: Lusatipollis. Comment: This feature is especially prominent in many representatives of the fossil pollen of the Normapolles group. See also: vestibulum.

Labrum (pl. labra, adj. labrate) (Couper and Grebe, 1961)
	The elevated and/or thickened part of a laesura between the commissure and the remainder of the proximal surface. See also: margo. Comment: The term is mainly used in the descriptions of fossil spores. Because of possible confusion with the term labrum (sensu Thomson and Pflug (1953)) it is, however, suggested to use the term margo instead.

Lacuna (pl. lacunae, adj. lacunate) (Wodehouse, 1928)
	A depressed area surrounded by ridges in lophate pollen grains. See also: abporal lacuna, circumpolar lacuna, equatorial lacuna, interporal lacuna, paraporal lacuna, polar lacuna, poral lacuna.

Laesura (pl. laesurae, suffix -lete) (Erdtman, 1946)
	The arm of a proximal fissura or scar of a spore. Comment: A monolete spore has one laesura, a trilete spore three (although some palynologists consider a trilete spore to have a single triradiate laesura). A laesura comprises a commissure which may be bordered by a margo (labrum). See also: monolete, trilete.

Laevigate (adj.)
	A general term for smooth, as if polished (Jackson, 1928). Synonym of psilate. Orthographical variant: levigate. Comment: Although the correct Latin spelling is levigate, the spelling laevigate is accepted throughout the botanical literature (Jackson, 1928). The term has mostly been used in the descriptions of fossil spores. Example: Laevigatisporites.

Lalongate (adj.) (Erdtman, 1952)
	Describing the shape of a transversely elongated endoaperture. Example: Filipendula (Rosaceae). See also: lolongate.

Lamella (pl. lamellae, adj. lamellar, lamellate)
	A general term for a thin layer (Jackson, 1928).

Latimurate (adj.) (Erdtman, 1952)
	Describing a pollen grain or spore with broad muri.

Latiporate (adj.) (Norem, 1958)
	Describing pollen grains with pores in one hemisphere only. Examples: Juglans, Carya (Juglandaceae).

Latitudinal (adj.)
	A general descriptive term, in palynology applied to features which run in lines parallel to the equator. Antonym: longitudinal. See also: sulcus.

Layer
	A general term. Applied in palynology to any distinct stratum of the sporoderm (APLF, 1975).

-lept (Erdtman, 1969)
	A suffix for thin, indicating that a pollen grain has a leptoma.

Leptoma (Erdtman and Straka, 1961)
	A thin area at the distal pole of a pollen grain, presumed to function as an aperture. Example: Pinus (Pinaceae). Comment: substitute term for cappula. See also: tenuitas.

-lete (Erdtman, 1969)
	A suffix to denote the presence (or absence) of laesura. Examples: alete, monolete, trilete.

Levigate (adj.)
	Orthographical variant of laevigate.

Limb (Wodehouse, 1935)
	Synonym of equatorial outline.

Limbus (Potonié and Kremp, 1955)
	A sharp narrow crease of the saccus or pseudosaccus where the outer and inner exine layers are fused. Example: Nuskoisporites dulhuntyi.

Linear tetrad (Erdtman, 1945b)
	A uniplanar tetrad in which the four members are arranged in a row. Example: Typha spp. (Typhaceae). See also: tetrad.

Lira (pl. lirae) (Erdtman, 1952)
	A narrow ridge which forms the murus in a striate pattern. Synonym of murus and vallum.

LO-analysis (Erdtman, 1952)
	A method for analyzing patterns of sexine organization by means of light microscopy. Comment: This method is valuable for elucidating exine patterns. When focused at high level (H), raised sexine elements appear bright (Lux), whereas holes in the tectum are relatively dark (Obscuritas). At lower focus (L) holes become lighter and the sexine elements become darker. See also: LO-pattern, OL-pattern.

Lobate (adj.) (Kuyl et al, 1955)
	Describing an equatorially aperturate pollen grain with a lobed shape in polar view. Comment: Belongs to a system of shapes combined with the position of the apertures as introduced by Kuyl et al.

Lolongate (adj.) (Erdtman, 1952)
	Describing the shape of a longitudinally elongated endoaperture. Example: Rumex spp. (Polygonaceae). See also: lalongate.

Longi-
	A prefix for long.

Longiaxe (adj.logiaxal) (Van Campo, 1966)
	Pollen grains with a polar axis longer than their equatorial diameter. Synonym of prolate (s.l.). Antonym: breviaxe. Comment: Thompson and Pflug (1953) recognised Longaxones as a group of mid-Cretaceous and younger angiosperm pollen contrasted with Brevaxones.

Longitudinal (adj.)
	A general descriptive term, in palynology applied to features which run in lines between the poles. Antonym: latitudinal. See also: lolongate.

LO-pattern (Erdtman, 1952)
	A pattern of ornamentation that appears to show "bright islands" at high focus (H) and that become dark at low focus (L), observed when using LO-analysis. Comment: The reverse of OL-pattern.

Lophate (adj.) (Wodehouse, 1935)
	Describing a pollen grain in which the outer exine is raised in a pattern of ridges (lophae) surrounding depressions (lacunae). Example: Hieracium (Compositae). See also: echinolophate, psilolophate.

Loxocolp(or)ate (adj.) (Erdtman and Straka, 1961)
	Describing zonocolp(or)ate pollen with ectocolpi arranged so that they converge in pairs. Comment: Such apertures generally occur in aberrant grains with more than the typical number of apertures.

Lumen (pl. lumina) (Potonié, 1934)
	The space enclosed by the muri. See also: brochus, reticulum.

Macrospore
	General term for the larger spores of heterosporous vascular plants (Jackson, 1928). Antonyms: microspore (in the general botanical sense); miospore (in the sense of Guennel, 1952) . Comment: In dispersed fossil spores where it is not always possible to determine whether the parent plants were heterosporous the term indicates size only (usually >200µm). See also: megaspore.

Maculate (adj.)(Potonié, 1934)
	A general descriptive term. In palynology it can be applied to pollen grains or spores with a spotted exine, often due to variations in internal exine structure. Example: Maculatisporites.

Margo (pl. margines, adj. marginate) (Iversen and Troels-Smith, 1950)
	An area of exine around an ectocolpus that is differentiated from the remainder of the sexine, either in ornamentation or by difference in thickness. See also: annulus, labrum.

Massa (pl. massae) (sensu Potonié, 1956)
	A specialised structure composed of aborted spores and tapetal material found on certain megaspores and often referred to as a floating apparatus. Applied only to megaspores. Examples: Azolla (Azollaceae), Cytosporites varius.

Massula (pl. massulae, adj. massulate)
	A general term for aggregations of pollen grains dispersed as a unit (Jackson, 1928). Examples: Mimosaceae, Periplocaceae. See also: dispersal unit, polyad, pollinium.

Medine (Saad, 1963)
	A term applied to a faintly lamellated, acetolysis resistant layer considered to be situated between intine and exine. See also: mesine.

Megaspore
	A general term for large spores of heterosporous vascular plants (Jackson, 1928). See also: microspore, macrospore.

Meiosis (adj. meiotic)
	The reduction division of chromosomes (Jackson, 1928).

Meiospore
	General term for a spore produced by meiosis (Jackson, 1928).

Melissopalynology (Maurizio and Louveaux, 1960)
	The study of pollen grains collected by bees, and/or found in honey. Comment: The variants melitopalynology (Erdtman, 1952) and melittopalynology (Fægri and Iversen, 1974) are sometimes encountered.

Membrana colpi (pl. membranae colpi) (Iversen and Troels-Smith, 1950)
	Synonym of colpus membrane.

Membrana pori (pl. membranae pori) (Iversen and Troels-Smith, 1950)
	Synonym of pore membrane.

Meridional (adj.) (Fægri and Iversen, 1950)
	Describing longitudinal features on the surface of a pollen grain or spore which run along lines perpendicular to the equator.

Meridionosulcus (adj. meridionosulcate) (Sampson, 1976)
	A meridional sulcus. Example: Degeneria vitiensis (Degeneriaceae). See also: zonasulcus.

Mesine (Rowley, 1959)
	A laminated, electron-dense layer considered to lie between the intine and the exine. Comment: Probably the same as the medine, but defined on different methods of microscopy. See also: medine.

Meso-
	A prefix meaning middle.

Mesoaperture (adj. mesoaperturate) (Thanikaimoni, 1980)
	The middle part of a compound aperture in which there is also an ectoaperture and an endoaperture. Example: Polygonum aviculare (Polygonaceae).

Mesocolpium (pl. mesocolpia) and Mesoporium (pl. mesoporia) (Erdtman, 1952)
	The area of a pollen grain surface delimited by lines between the apices of adjacent colpi or the margins of adjacent pores. See also: apocolpium, apoporium, intercolpium, interporium.

Metareticulum (adj. microreticulate) (Borsch and Bathlott, 1998)
	A reticulum wich is characterized by the consistent presence of one porate aperture in each lumen. Examples: Froelichia floridana (Amaranthaceae), Viviania rosea (Vivianiaceae), Kallstroemia maxima (Zygophyllaceae).

Micro-
	A prefix for small. Comment: In palynology, generally used to denote features less than 1µm. Examples: microechinate, microverruca. See also: nano-.

Microreticulum (adj. microreticulate) (Praglowski and Punt, 1973)
	A reticulate ornamentation consisting of muri and lumina smaller than 1µm. See also: reticulum.

Microspore
	A general term for the smaller spores of heterosporous plants, that is, the spores from which the microgametophyte develops (Jackson, 1928). Antonyms: macrospore, megaspore. Comment: The term is sometimes used in palaeopalynology for small spores generally, whether homospores, microspores or even small megaspores. This usage should be avoided, in favour of the terms miospore or small spore, but only if it is not known the plant is homosporous or not. A pollen grain, is the microgametophyte of a seed plant. In developmental studies, a pollen grain is sometimes referred to as microspore until microspore mitosis. See also: miospore, pollen.

Microsporocyte
	The mothercell of a microspore or pollen grain (Jackson, 1928). See also: pollen mother cell.

Middle part ( Punt and Rentrop, 1973)
	Synonym of mesoaperture .

Miospore (Guennel, 1952)
	A general term for all fossil plant spores smaller than 200µm, regardless of whether they are isospores, microspores, small megaspores, prepollen or pollen grains. Antonym: macrospore. See also: microspore, pollen.

Mitosis
	A general term for nuclear division involving no reduction of chromosomes (Jackson, 1928).

Monad (Selling, 1947)
	A pollen grain or spore dispersed as an individual unit, rather than in association with others, such as in a dyad, tetrad or polyad.

Mono-
	A prefix for one.

Monoaperturate (adj.)
	Describing a pollen grain or spore with a single aperture. Comment: Examples: monocolpate (Iversen and Troels-Smith, 1950), monoporate (Iversen and Troels-Smith, 1950) monosulcate (Erdtman, 1952).

Monolete (adj.) (Erdtman, 1943)
	Describing a spore with a single laesura. Example: Dryopteris (Dryopteridaceae). See also: trilete.

Monosaccate (adj.) (Potonié and Kremp, 1954)
	Describing a pollen grain with a single saccus. Example: Florinites antiquus. See also: bisaccate.

Morphon (Van der Zwan, 1979)
	A group of form-species exhibiting continuous variation of morphological characteristics in a single time sequence ("horizontal" variation). Comment: Many authors use the word "complex" in a very similar way. See also: palynodeme.

Multibaculate (adj.) (Erdtman, 1952)
	Synonym of pluricolumellate.

Multiplanar tetrad (Walker and Doyle, 1975)
	A tetrad in which the individual members are arranged in more than one plane. Comment: Decussate and tetrahedral tetrads are multiplanar, whereas rhomboidal, linear and T-shaped tetrads are; uniplanar.

Murornate sculpture elements (Smith and Butterworth, 1967)
	Elevations of the general surface. Examples: cristae, muri.

Murus (pl. muri) (Erdtman, 1943)
	A ridge that is part of the ornamentation and, for example, separates the lumina in a reticulate pollen grain or the striae in striate pollen grain. Comment: Muri in striate patterns are sometimes called valla (Iversen and Troels-Smith, 1950) or lirae (Erdtman, 1952).

Nano- (Erdtman, 1969)
	A prefix for elements smaller than 0.5µm. See also: micro-.

Negative reticulum (Erdtman, 1943)
	A general term used to describe patterns of ornamentation in which sexine areas are separated by narrow, reticulately arranged grooves. See also: areola, frustillum.

Nexine (Erdtman, 1952)
	The inner, non-sculptured part of the exine which lies below the sexine. Antonym: sexine. Comment: Although the term endexine as originally defined (sensu Erdtman, 1943) was more or less synonymous with nexine it no longer is because endexine is now invariably used in the sense of Fægri (1956). Nexine and sexine are distinguished on purely morphological criteria, whereas ectexine and endexine differ in their staining properties. The two sets of terms therefore have slightly different applications. See also: endexine (sensu Fægri, 1956).

Nexine 1 (Erdtman, 1966a)
	Synonym of foot layer, pedium, sole.

Nexine 2 (Erdtman, 1966a)
	Synonym of endexine.

Non-aperturate (adj.) (Fægri and Iversen, 1950)
	Synonym of inaperturate.

Normapolles (Pflug, 1953)
	A group of Cretaceous and Lower Palaeogene pollen, usually triporate, with a complex pore apparatus.

NPC-classification (Erdtman and Straka, 1961)
	A morphological system for classifying pollen grains and spores that was based on the number, position and character of their apertures.

Nudate (adj.) (Punt et al., 1976)
	Synonym of psilate.

Oblate (adj.) (Erdtman, 1943)
	Describing the shape of a pollen grain or spore in which the polar axis is shorter than the equatorial diameter. Comment: This term belongs to the system of shape classes suggested by Erdtman (, extended in ), based on the measurements of the polar axis (P) and equatorial diameter (E). In this system oblate is defined as a ratio between the polar axis and the equatorial diameter of 0.50-0.75. See also: oblate spheroidal, P/E ratio, peroblate, perprolate, prolate, prolate spheroidal, shape classes, spheroidal, suboblate, subprolate. subspheroidal.

Oblate spheroidal (adj.) (Erdtman, 1952)
	Describing the shape of a pollen grain or spore in which the ratio between the polar axis and the equatorial diameter is 0.88-1.00. See also: oblate, P/E ratio, peroblate, perprolate, prolate, prolate spheroidal, shape classes, spheroidal, suboblate, subprolate. subspheroidal.

Ocellus (pl. ocelli, adj. ocellate) (Grebe, 1971)
	Synonym of cata-ulcus. See also: ulcus.

Oculus (pl. oculi, adj. oculate) (Thomson and Pflug, 1953)
	The much enlarged part of the pore structure in pollen of the fossil Normapolles group. Example: Oculopollis. Comment: The enlarged part is a swelling of the outer wall layer on one or both surfaces of a grain in the region of an exogerminal. An annulus is uniformly thick and completely surrounds the exogerminal region. See also: annulus.

OL-pattern (Erdtman, 1952)
	A pattern of ornamentation that appears to show "dark islands" at high focus (H) and that become bright at low focus (L). Comment: The reverse of a LO- pattern.

Omniaperturate (adj.) (Thanikaimoni, 1984)
	Describing a pollen grain in which the exine is very thin or absent and the intine is thick, so that no specific apertural region can be distinguished and thus the whole surface can be considered apertural in nature.

Oncus (pl. onci) (Hyde, 1955).
	A lens-shaped structure that is not resistant to acetolysis and occurs beneath the apertures of many kinds of pollen grains. Example: Corylus (Betulaceae). See also: Zwischenkörper.

Operculum (pl. opercula, adj. operculate) (Wodehouse, 1935)
	A distinctly delimited sexine/ectexine structure which covers part of an ectoaperture and which is completely isolated from the rest of the sexine. See also: pontoperculum.

Optical (cross-) section
	The image seen in optical microscopy when the plane of focus is half way through a palynomorph.

Orbicule (pl. orbicules, adj. orbicular)
	A general term, applied in palynology for an orbicular granule of sporopolleninsporopollenin. Synonym of Ubisch body.

Ordinate (adj.) (Iversen and Troels-Smith, 1950)
	Describing a pollen grain or spore with an arrangement of elements regularly distributed. Antonym: inordinate. Comment: The elements can be of structural or sculptural origin. Examples: columellae under a tectum forming a reticulum (example: Vaccaria pyramidata, Caryophyllaceae); scabrae on the tectum (example: Alchemilla glabra, Rosaceae) arranged in a regular pattern.

Ornamentation (Potonié, 1934)
	A general term that is useful for describing the organisation of features. See also: pattern, sculpture.

Ornate (adj.) (Erdtman, 1953)
	Describing a reticulate ornamentation consisting of broad, curved muri and lumina that are often anastomosing. Example: Ceiba aesculifolia (Bombacaceae).

Orthocolpate (adj.) (Erdtman and Straka, 1961)
	Describing a pollen grain with the colpi in the most common position, perpendicular to the equator. Comment: This term is not needed in most instances, where zonocolpate would suffice, but exists to contrast with the term loxocolpate.

Os (pl. ora, adj. orate) (Erdtman, 1952)
	Synonym of endoaperture. Comment: The term is now mainly used in so far as that ora is a component of the terms colporus and pororate.

Outline
	A general descriptive word. Applied in descriptive terms like equatorial outline and outline in polar view.