Glossary - general

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Abaxial – the side of an organ that faces away from the axis bearing it (i.a. the lower surface of a leaf) – Opposite: adaxial

Abortion – suppression/reduction of parts which are usually present, partway through their development (usually of flowers or fruits)

Abortive – imperfectly developed, not grown to its normal size or function

Abruptly pinnate – a pinnate leaf without an odd terminal leaflet; the term paripinnate is preferred

Abscission (of leaves or rarely branches) – detaching from the stems bearing them at a predetermined place, the abscission zone

Acalymmate pollen tetrad – tectum not crossing the junction between tetrads

Acanthophyll – (Arecaceae) leaflet of a pinnate leaf modified in the form of a spine

Acarodomatia – small pockets in leaves, in the axils of the veins on the abaxial surface, theoretically harbouring mites (Acari); usually contracted to ‘domatia’

Acaroid resin – (Xanthorrhoeaceae) reddish to yellowish resin, forming an insoluble, hard and very resistant layer at high temperature

Acarpellate – without carpels – Opposite: carpellate

Acaulous – without a (visible) stem

Accessory branch – secondary branch

Accessory fruit – false fruit, conspicuous but without other function than attraction

Accessory bud – additional to axillary buds, and assuming their function

Accrescent – increasing in length or thickness with age (e.g. the calyx after flowering)

Accumbent – lying against (i.a. the cotyledons against the radicula)

Accumbent embryo – folded in a way so that the radicula is directed against the edges of the two cotyledons; the cotyledons in an embryo developed from a curved ovule (accumbent embryo) are in the plane formed by the longitudinal axis of the seed and the chalaza

Acetabuliform (of nectariferous disc etc.) – (Euphorbiaceae etc.) saucer-shaped

Achene – a small dry thin-walled fruit, indehiscent (not splitting when ripe), and containing a single seed; the term is normally used for a fruit formed by a single carpel – see Nut

Acicular – needle-shaped; very narrow, stiff, and pointed (i.a. leaf tips)

Acolumellate exine – exine without columellae (bacula)

Acolyte – (Arecaceae) sterile male flower found together with a fertile female flower as a flower pair in the inflorescence of Calamus

Acrodromous venation – two or more primary (or well developed secondary) veins diverge at or above the lamina base and run in convergent arches toward the apex; arches not curved basally

Acropetal(ous) – in the direction of the apex – Opposite: basipetal(ous)

Acropetal venation – venation developing from the base towards the apex

Actinocytic stomata – radiate-celled stomata; two guard cells surrounded by a circle of radiating subsidiary cells; with five or more somewhat radially enlarged or elongated subsidiary cells surrounding the guard cells

Actinodromous venation – three or more primary veins diverge radially from a point at or above the lamina base and proceed towards the margin

Actinomorphic flower – radially symmetrical, polysymmetrical; regular, radially symmetric

Actinostelic – uninterrupted central vascular cylinder with radiating ribs

Aculeate – armed with prickles (as distinct from thorns)

Aculeus (pl. aculei) – sharp point(s), prickle(s)

Acuminate – tapering to a long tip (usually of leaf tips)

Acute – sharp, sharply pointed, the margins near the tip being almost straight and forming an angle of <90o – Opposite: obtuse

Adapical – towards the apex

Adaxial – the side of an organ towards the axis on which it is inserted (e.g. the upper surface of a leaf) – Opposite: abaxial

Adherent (of different organs) – attached but not fused

Adjacent-ligular – (Arecaceae) germination type where the shoot is carried out of the seed within the very short ligule of the cotyledon

Adnate – (usually of different organs) attached to, surface to surface (e.g. stamen adnate to petal)

Adplicate ptyxis – flat vernation; plane

Adventitious buds – buds produced elsewhere than normal (such as from the stem instead of, as usual, in leaf axils)

Adventitious embryony – the embryo arises from the diploid megasporangium tissue which surrounds the megagametophyte

Adventitious roots – lateral roots arising from organs (e.g. the stem) other than the main root system

Aerenchyma – air canal consisting of thin-walled cells and large intercellular spaces in roots and shoots of many aquatic or hygrophilous plants, allowing the exchange of gases

Aerenchymatous – adjective of the noun aerenchyma

Aerial leaves (of aquatic plants) – leaves which are neither submerged nor floating

Aerial roots – roots emerging from the plant entirely above the ground surface

Aerial stem – a stem or part of a stem which is not submerged, floating or below the ground surface

Aestivation – the way in which sepals or petals are folded/packed in bud

Agglomerated – densely crowded, but not stuck together

Agglutinated – stuck together

Aggregated – in a dense mass, the individual parts touching

Aggregate fruit – an assemblage of fruits formed from the free (i.e. not connate) carpels of a single flower with apocarpous gynoecium

Alae – wings, lateral petals

Alate – winged

Albumen – antiquated term for endosperm, nutritive substance accompanying the embryo

Albuminous – with albumen, the nutritive substance in the seed

Aliform axial parenchyma – a paratracheal axial parenchyma in which lateral wings are present as seen in cross-section; parenchyma cells surrounding or at one side of the vessel and with lateral extensions

Allelocytic stomata – with an alternating complex of three or more C-shaped subsidiary cells of graded sizes surrounding the guard cells

Alternate – inserted at different levels of the axis

Alternate lateral wall pitting (of vascular tissue) – intervascular pits spirally distributed across the vessel elements, either on vessel-vessel interfaces or on vessel-ray interfaces

Alternipetalous – alternating with the petals

Alternisepalous – alternating with the sepals

Alternitepalous – alternating with the tepals

Altingioid leaf tooth – basically asymmetrical, with a persistent transparent gland at the apex, and with their lateral veinlets free, not reaching the medial vein

Alveolate – with pits resembling a honeycomb

Alveoli – surface cavities or depressions, like a honeycomb

Amentiferous – bearing catkins

Amentiform – resembling a catkin

Ament(um) – a slender, often pendulous, cylindrical inflorescence with crowded (sub)sessile unisexual apetalous flowers, falling as a whole after fruiting

Amoeboid tapetum – see Amoeboid-periplasmodial tapetum

Amoeboid-periplasmodial tapetum – the young microsporocytes are in the centre of the anther locule and surrounded by tapetal cells; as the microsporocytes separate, the cell walls of the tapetal cells degenerate and develop plasmodesmata which connect the protoplasts of the tapetal cells; the protoplasts fuse and form a multinucleate periplasmodium surrounding the microsporocytes/pollen tetrads; the periplasmodium is enclosed by a perispore membrane

Amphianisocytic stomata – the two guard cells are covered by four subsidiary cells in two layers at right angles (not parallel) to the guard cells

Amphibious – plants adapted to life both on land and in water

Amphicarpous – (Schoenoplectus in Cyperaceae) applied to a small secondary inflorescence occurring at the base of the culm

Amphicribral vascular bundles – with the phloem surrounding the xylem in some concentric vascular bundles – Opposite: amphivasal

Amphisarca – indehiscent multilocular many-seeded fruit, with a dry and hard outer part and a pulpy and soft inner part (i.a. a melon)

Amphitropous ovule – with the ovule apex and the stalk base next to each other and with the megagametophyte curved; attached near its middle, half-inverted, with the raphe terminating approximately half-way between the chalaza and the orifice

Amphivasal vascular bundles – with the xylem surrounding the phloem in some concentric vascular bundles – Opposite: amphicribral

Amplexicaul – embracing the stem, e.g. with the leaf base extending to the side of the stem opposite to the main blade

Ampulliform – swollen in the shape of a flask (e.g. the corolla in Erica)

Ana-amphitropous ovule – a type of amphitropous ovule, in which the trace proceeds a distance along one side of the ovule prior to reaching the megasporangium

Anacampylotropous ovule – a type of campylotropous ovule, in which the trace proceeds half-way up along one side of the ovule prior to reaching the megasporangium

Anantherous filament – without an anther

Anastomosing – forming a network

Anastomosis – union of one vein with another, the connection forming a network

Anasulcate pollen grain – with sulcus/sulci distal on the pollen grain

Anatomy – internal structure

Anatrichotomocolpate pollen grain – with three-armed colpus distal on the pollen grain

Anatropous ovule – reversed; inverted at 180o parallel to its stalk so the micropyle is close to the point of funiculus attachment

Anaulcerate pollen grain – with ulcus/ulci distal on the pollen grain

Androclinium – see Clinandrium

Androdioecious – with some plants bearing only functionally hermaphrodite flowers and other plants functionally male flowers

Androecium – a collective term for the stamens in a flower

Androgynophore – a stalk carrying both stamens and carpels/ovary above the insertion of the petals

Andromonoecious – a plant with both male and hermaphrodite flowers, but without female flowers

Androphore – a stalk on which the stamens are carried

Andropodium – a structure consisting of connate staminal bases

Anisocytic stomata – unequal-celled stomata; the two guard cells are covered by three subsidiary cells, of which one is markedly smaller than the other two; with three subsidiary cells, two large and one smaller, surrounding the guard cells

Anisophyllous – where the two opposite leaves at a node are of very unequal size or shape

Anisomorphic leaves – leaves of usually two different morphological types on the same shoot or at least on the same plant

Annual shoot – shoot sprouting from the perennial root/stem system and lasting only one growing season

Annular – in the shape of a ring; used of any organs arranged in a circle

Annulus (pl. annuli; of pollen grains) – area of exine surrounding a pore and sharply differentiated from the remainder of the exine

Anomalous – out of the ordinary, unlike others in its group

Anomalous secondary growth – secondary (lateral) growth that does not follow the normal pattern of a single vascular cambium producing xylem to the inside and phloem to the outside

Anomocytic stomata – the stoma is surrounded by a varying number of subsidiary cells resembling normal epidermal cells (the subsidiary cells with the same appearance as the guard cells); stomata lacking differentiated subsidiary cells surrounding the guard cells

Anomotetracytic stomata – the guard cells are surrounded by four irregularly arranged subsidiary cells

Anomotreme pollen grain – with irregular aperture(s)

Antepetalous (oppositipetalous) – opposite to a petal, and not alternate with it

Anterior – positioned in front, turned away from the axis

Antesepalous (oppositisepalous) – opposite to a sepal, and not alternate with it

Antetepalous (opposititepalous) – opposite to a tepal, and not alternate with it

Ant galls – inflated, ultimately woody structures from the usually fused bases of stpules in some Acacia species; hollow, an often inhabited by ants

Anther – the part of the stamen containin the pollen

Anther collar – (Asteraceae) a region of swollen or otherwise demarcated cells at the apex of the filament(s)

Anther pit – the filament tip is immersed in a narrow concavity such that the attachment point of the anther is hidden

Anther pseudopit – the thecae partially surround the filament at the attachment point of the anther but do not form a complete pit

Antheriferous – bearing anthers

Antherodes – remnants of anthers; staminodia

Anther placentoid – a placenta-like parenchymatous structure arising from the inner wall of the anther in some plants

Anthesis – time of pollination of the flower; time of receptivity of stigma, or distribution of pollen

Anthocarp – a pseudocarp formed from a single flower, the fruiting structure being covered by an accrescent perianth or calyx; in Nyctaginaceae consisting of the fruit and the perianth base

Anthophore – an elongated internode present between the sepals and the ovary and between the petals and the stamens

Anticlinal – perpendicular (at right angles) to the surface

Anticous – most distant from axis, turning away from axis

Antipode – the chalazal part of the megagametophyte

Antitropous ovule – the ovule is curved (anatropus) in the opposite direction to the carpel curvature, corresponding more or less to epitropous

Antrorse – pointing towards the distal end, upwards or forwards – Opposite: retrorse

Antrorsely – upward or forward

Anulopunctate tectum (of pollen grains) – with puncta less than 0.3 µm in diameter

Apert aestivation – see Open aestivation

Aperturate – with an opening, not closed

Aperture (of pollen grains) – specialized area of the sporoderm, which is thinner than the remaining sporoderm (usually also differing in structure and ornamentation)

Apetalous – without petals

Apex – distal end, tip – Opposite: base

Aphlebia – (Arecaceae) a narrow, strap-like, very spiny leaflet quite different in form from normal leaflets, found at the very base of the adult sessile leaves of, i.a., Eremospatha and Laccosperma

Apical – of the apex; distal

Apical placentation – the placenta is situated at the apex of the ovary

Apicidal capsule – dehiscing at the apex

Apicifixed anther – hanging, seemingly attached at the top

Apical meristem (intermediary or open) – minute meristem present in the growing tips of roots or buds

Apical placentation – one or several ovules developing at the apex (top) of the ovary

Apical septum – a septum in the upper part of the ovary, which originates by the bulging up of the locules such that the stylar canal traverses it

Apiculate – ending in an abrupt, short point

Apiculus – short, sharp, but not stiff point

Apocarpous – with free carpels, most noticeable in fruit – Opposite: syncarpous

Apocole – the elongated (usually subterranean and non-photosynthetic) part of the cotyledonary hyperphyll below the haustorium and above the cotyledonary sheath in monocotyledons

Apocolpium (of pollen grains) – an area at the pole of a zonocolpate pollen grain, which is delimited by lines connecting the apices of the colpi

Apotact aestivation – a form of cochlear aestivation, where the perianth part with its two margins outside those of the adjacent tepals are not immediately next to the one with the two margins inside

Apotracheal axial parenchyma – metatracheal axial parenchyma; axial parenchyma which is not associated with vessels

Apotracheal banded parenchyma – axial parenchyma consisting of bands two or more cells wide; narrow-banded (sensu Carlquist): bands two or three cells wide; wide-banded (sensu Carlquist): bands more than three cells wide

Apotropous ovule – an anatropous ovule with a ventral raphe (ovule curved abaxially)

Appendicular epigyny – the initially convex ovary becoming inferior by early vertical growth beneath the tepals making the entire apical meristem concave; initiation of the youngest floral primordia occurs on this concave meristem; the inferior ovary forms through congenital adnation of the carpels to the bases of the tepals and stamens; a central concavity develops in the convex top of the floral axis due to development of appendicular tissues

Appendiculate – with appendage or appendages

Appressed – lying close and flat (e.g. hairs on a stem)

Aquatic – living in water

Arachnoid (type of indument) – cobweblike, tangled cottony, the hairs in several directions and tangling

Arborescent – becoming tree-like

Arbuscular endomycorrhiza – vesicular mycorrhiza; a type of mycorrhiza with glomeromycetes, in which the fungus penetrates the cortical cells of the roots; the mycorrhiza forms highly branched characteristic structures, arbuscules or vesicles, exchanging water and nutrients; in the Arum type hyphae grow in the intercellular space, whereas in the Paris type hyphae grow between the cells

Arbutoid mycorrhiza – penetrating the outer cortical cells of the hair roots, although these are covered by a Hartig net, in which the hyphae grow along the cell walls or form an entire envelope

Archespore – one or several cells from which the megasporocyte or microsporocyte develops; the archespore may be unicellular or multicellular

Arcuate – curved like a bow

Areolate – with an areole or areolae, divided into distinct spaces by boundary lines

Areole (areola, pl. areolae) – areas on a surface divided from similar areas by a division line such as a vein; in Cactaceae: a modified axillary short shoot

Areolate tectum (of pollen grains) – with areoles present in the tectum

Aril – an appendage partially or completely enveloping the seed, sometimes resembling a third integument, and arising from the funicle (or the hilum?)

Arillar collar – (Annonaceae) fleshy organ around the hilum, an outgrowth of the seed coat

Arillate seed – provided with an aril

Arilloid (of seed appendages) – arillode; resembling an aril but non-funicular in origin

Arista – a long, bristle-like, pointed axis

Aristate apex – with a long, bristle-like point

Aristulate – bearing a small, sharp bristle

Armature – general term for the presence of spines, prickles etc

Arm cells (of leaves) – (Poaceae) chlorenchyma cells with cell wall invaginations

Armed – with sharp defensive structures

Aromatic – producing volatile oils with discernible odours (fragrance)

Article – a segment of a fruit constricted at intervals and breaking along these constrictions (in e.g. a lomentum)

Articulated – jointed

Ascending funicle, ovule, or stem – curved upwards, growing upward (sometimes indirectly)

Ascidiate carpel – tubular to pitcher-shaped, widening in upper part; the carpel primordium is initially U-shaped, and if the area between the arms of the U becomes meristematic (the meristematic cross-zone), the carpel develops as if it were a tube – Opposite: plicate carpel

Asepalous – without sepals

Asperous – rough

Asperulate – slightly rough with small hairs

Asperulous – slightly rough

Asterad embryogenesis – a three-tiered proembryo is formed with a vertical division in the apical cell and a transverse division in the basal cell; the apical cell may divide by an oblique wall and, at the time of formation of a quadrant, a wedge-shaped epiphysis initial is cut off which later gives rise to the epicotylary region; the remaining three cells of the quadrant produce the cotyledons; the middle cell of the proembryonic tetrad gives rise to the entire hypocotyledonary region

Asterosclereid, astrosclereid – a fairly short sclerenchyma cell (sclereid) that differs from a brachysclereid by its often conspicuously branched shape

Astringent taste – making the mouth pucker, bitter

Asymmetrical – with the two sides of the part or organ not equal – Opposite: symmetrical

Atactostele – a type of stele in which the vascular bundles are arranged irregularly within the parenchyma (ground tissue)

Atectate pollen grain – see Intectate

Atropous ovule – see Orthotropous ovule

Attenuate – gradually tapering over a long distance

Aulacospermous – individual endothelial cells in a seed protrude into the endosperm, the endosperm hence becoming alveolate

Auricle – ear-like lobe

Auricled – see Auriculate

Auriculate – equipped with ear-like structures, usually near the base

Autogamous – self-fertilizing, when ovules are fertilized by pollen grains from the same flower

Awl-shaped – gradually tapering to a sharp thin point

Awn – (Poales) a fine bristle ending an organ

Axial parenchyma – type of secondary xylem parenchyma, in which the parenchyma cells originate from fusiform cambial initials; the cells of the axial parenchyma may be as long as the fusiform initials from which they originated or, usually, much shorter due to transverse division prior to the differentiation

Axicorn – (Campanuloideae) tissue on the inside of the fruit, which by its drying perforates the pericarp and allows the seed being dispersed

Axil – the angle between the stem and the leaf

Axile – belonging to the axis

Axile placentation – the ovules are attached to the axis of the ovary, to the inner angle of the cells of a syncarpous ovary, in which the placentas are situated in separate locules; the ovules are attached along the sutures of the closed carpel, i.e. in the corner formed by the ventral areal of the carpel in an apocarpous or syncarpous gynoecium

Axillary – arising in an axil, the point between the stem and the leaf or another organ which arises from the stem

Axillocytic stomata – stoma in an axillary position attached to two lateral walls at the distal, marginopolar end of the single subsidiary cell

Axis – main line of development of a plant or organ; (of inflorescence) the main stem or branch part from which the flowers are produced; (of ovary) the central column or the central part where the inner angles of the cells meet