Glossary of botanical terms

This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology. For other related terms, see Glossary of phytopathology and .

The shedding of an organ that is mature or aged, as of a ripe fruit or an old leaf.
With affinity to others, akin to; often used for a provisionally recognized but unnamed taxon considered close to that name, perhaps a hybrid or extreme variant.
a comb-like series of veins forking from a single side of a primary or secondary vein
A connection or fusion of two or more that are normally diverging or branching, thereby forming a network.
The condition of having a floral with a different (usually smaller) number of parts from the other floral whorls.
A plant that completes its life cycle (i.e. germinates, reproduces, and dies) within a single year or growing season.
2.  (of a flowering plant) The period during which flowers in anthesis are present. Not defined for some cases, such as when pollen is released in the bud.
A secondary part attached to a main structure; an external growth that seldom has any obvious function, hence .
A plant whose natural habitat is water, living in or on water for all or a substantial part of its lifespan; generally restricted to fresh or inland waters.
A multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete. The corresponding male organ is called the antheridium.
The upper angle between one part of a plant and another, e.g. the stem and a leaf.
Borne in or arising from the , usually referring to the axil of a leaf.
occur on the spines of some species of cactus, as shown here enlarged.
A plant which completes its life cycle (i.e. germinates, reproduces, and dies) within two years or growing seasons. Biennial plants usually form a basal of leaves in the first year and then flower and fruit in the second year.
A fine white or bluish waxy powder occurring on plant parts, usually stems, leaves, and fruits. It is easily removed by rubbing.
A plant that loses all of its leaves only briefly before growing new ones, so that it is leafless for only a short time, e.g. approximately two weeks.
A thick storage organ, usually underground, consisting of a stem and leaf bases (the inner ones fleshy).
Structure of flower of an orchid in genus Praecoxanthus, with the callus labelled
Not all chloroplasts are simple in shape. Chloroplasts of Spirogyra are helical within the tubular cells of their algal filaments.
2.  Undifferentiated tissue growth formed in response to wounding; may be grown in vitro.
A tissue layer that provides partially undifferentiated cells for plant growth.
Approaching white in color, as in a leaf covered with white down or wool.
1.  (of an ) Having a knob-like head, with the flowers unstalked and aggregated into a dense cluster.
1.  The basic, microscopic unit of plant structure, generally consisting of compartments in a viscous fluid surrounded by a .
An alternative spelling of , meaning Tufted or turf-like, e.g. the growth form of some grasses.
An individual composed of two or more genetically distinct tissues, most commonly as a result of a and sometimes by mutations that occur during cell division or cellular transfers during seed development.
A plant derived from the asexual vegetative reproduction of a parent plant, with both plants having identical genetic compositions.
2.  In grasses, the lower, stouter, and usually twisted part of an , distinct from the slender upper part or bristle.
A name often of no botanical standing and not governed by the ICNCP. The term generally applies to names such as Trademark Names, names covered by Plant Breeders Rights, Patents and Promotional Names, which are often used to enhance the sale of a plant.
An ecological assemblage of plants that characteristically occur together.
Flattened lengthwise, either laterally (from side to side) or dorsally (from front to back).
3.  A type of vernation of two leaves at a , in which one half of each leaf is exposed and the other half is wrapped inside the other leaf.
2.  In grasses, a hardened ring of tissue surmounting the in some species.
The primary leaf or leaves of a plant embryo which upon germination develops into the seed-leaf or the first set of leaves.
In the shape of a saucer or shallow cup; hemispherical or more shallow.
A plant whose origin or selection is primarily due to intentional human activity.
Curving downward, and then upward at the tip. Often qualified, e.g. declinate-ascendant.
1.  (intr. v.) To shed the outer bark of a tree, usually seasonally as part of the natural growth cycle.
2.  (tr. v.) To strip the peel, crust, bark, or other surface tissues from a plant or from harvested material, such as in extracting fibre from harvested Agave leaves.
Having branches growing horizontally along the ground but which are turned up at the ends.
Shaped like the uppercase Greek letter Δ, i.e. like a more or less equilateral triangle.
(of vascular plants) Having male and female reproductive structures which develop only on different individuals and never on the same individual. Contrast .
Occurring in widely separated geographic areas, distinctly separate; applies to a discontinuous range in which one or more populations are separated from other potentially interbreeding populations with sufficient distance so as to preclude gene flow between them.
Water lilies and reeds represent two ecological categories of aquatic vegetation.
The range of environmental conditions in which an organism can survive.
A three-dimensional shape that is in all sections through the long axis.
The innermost layer of the wall of a fruit; in a , the stony layer surrounding the seed.
The part of the plant axis or stem between the node and the first foliage leaves.
A plant, alga or fungus that grows on another plant without deriving nourishment from it but using it for support.
Deliberate introduction by seedlings, seeds or plants in a new habitat by humans.
In nomenclature, indicating that the preceding author proposed the name but did not legitimately publish it, and that the succeeding author referred to the first author when legitimately publishing the name. See Author citation (botany).
A single cross; a plant breeding term for the result of a repeatable cross between two pure bred lines.
A plant breeding term for the result of a plant arising from a cross between two F1 hybrids; may also refer to self-pollination in a population of F1 hybrids.
Covered with very dense, interlocked and matted hairs with the appearance or texture of felt or woollen cloth.
Capable of producing fruit; of flowers when they produce seed or of anthers containing pollen.
2.  Any very narrow, thread-like structure that is one or a few cells thick.
A split or crack, often referring to fissured bark; a line or opening of dehiscence.
Depending on the degree of maturation of the stamens, the style moves up or down (cataflexistyle or (ana-)hyperflexisyle).
2.  an enumeration of them, generally with a guide to their identification (e.g. the present volume, the Flora of Victoria, the Flora of New South Wales and so on). In this case 'flora' is written with a capital F.
A graphical means to describe flower structure, usually a schematic cross-section through a young flower.
A description of flower structure using numbers, letters and various symbols.
Preceded by a number: having a certain number of leaflets; for example, 3-foliate, "having three leaflets"
Vegetation dominated by trees with single trunks (including closely arranged trees with or without an understory of shrubs and herbs).
A taxonomic category subordinate to species and within the taxonomic hierarchy, below (varietas), and usually differentiated by a minor character.
Not united with other organs of the same type; not attached at one end.
Of placentation, ovules attached to a free-standing column in the centre of a unilocular ovary.
Rod-shaped and narrowing gradually from the middle toward each end; spindle-shaped.
Longitudinal section of immature male pine cone, showing male s (pollen grains) developing between the cone scales
An overhanging, helmet-shaped, structure that protects the reproductive parts from precipitation, wind or unwanted visitors.
Abnormal outgrowth on external plant tissues, caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites.
A cell or nucleus that fuses with another of the opposite sex during sexual reproduction.
1.  of seeds, describing the complex sequence of physiological and structural changes that occur from resting to growth stage.
2.  of a pollen grain; production of a pollen tube when contacting a stigma receptive to it.
3.  of a spore of fungi/bacterium; change of state – from resting to vegetative.
(of part of an organ) Swollen, usually with a pouch-like enlargement at the base.
1.  Lacking surface ornamentation such as hairs, scales or bristles; smooth.
2.  A term applied to describe a plant that covers the soil surface so densely that it smothers all beneath it.
Having or appearing to be spotted with oil droplets; of spores, having oil droplets inside.
Of a species, with some plants bearing only flowers and others bearing only female flowers.
The general external appearance of a plant, including size, shape, texture, and orientation.
The place where a plant lives; the environmental conditions of its home.
A single elongated cell or row of cells borne on the surface of an organ.
A plant adapted to living in highly saline habitats; a plant that accumulates high concentrations of salt in its tissues.
The controlled act of pollination that excludes the possibility of open-pollination.
process by which pollen grains in arid environments close off their apertures to avoid losing water
In parasitic plants, a structure developed for penetrating the host's tissues.
Having parts, especially leaves, that are distinctly different between the juvenile and adult stages.
Having two or more distinct morphologies (e.g. of different size and shape). Compare .
The condition of a species having flowers with different style and stamen lengths, but with all the flowers of any one plant being identical. see:.
Covered with a greyish to whitish layer of very short, closely interwoven hairs, giving a frosted appearance.
2.  as an invalid name derived from horticultural writings of confused authorship.
The protective outer covering of certain seeds, for example, the leafy outer covering of an ear of maize (corn), the leathery covering of the walnut or the spiky covering of the chestnut.
A plant produced by the crossing of parents belonging to two different named groups, e.g. genera, species, varieties, subspecies, forma and so on; i.e. the progeny resulting within and between two different plants. An F1 hybrid is the primary product of such a cross. An F2 hybrid is a plant arising from a cross between two F1 hybrids (or from the self-pollination of an F1 hybrid).
The names of the parents of a hybrid joined by a multiplication sign, e.g. Cytisus ardonoi × C. purgans.
A form of pollination whereby pollen is distributed by the flow of waters.
Of an embryo or seedling, the part of the plant axis below the cotyledon and node, but above the root. It marks the transition from root to stem development.
A cell, especially of a , differing markedly from surrounding cells. They often synthesise specialised products such as crystals.
In nomenclature, where the preceding author published the name in an article or book, authored or edited by the succeeding author.
The production of offspring between closely related parents leading to a high degree of similarity; self-fertilization is the most intense form of inbreeding.
Cut deeply and (usually) unevenly (a condition intermediate between toothed and lobed).
A flower which lacks one or more of its usual parts, such as carpels, sepals, petals, pistils, or stamens.
An abbreviation of Latin inedita, an unpublished work. Used to indicate that a botanical name appeared only in a manuscript that was not published, so the name is invalid.
native to the area, not introduced, and not necessarily confined to the region discussed or present throughout it (hardly distinct from ‘native’ but usually applied to a smaller area). For example, the Cootamundra Wattle is native to Australia but indigenous to the Cootamundra region of southern New South Wales. Compare .
a collective term for a surface covering of any kind of trichomes, e.g. hairs, scales.
several flowers closely grouped together to form an efficient structured unit; the grouping or arrangement of flowers on a plant.
denoting taxonomic ranks below the genus level, for example, subgenera, sections, and series.
inside the stamens or , usually referring to the location of a nectary disk.
Use of names not validly published according to the Code, i.e. they are not strictly 'names' in the sense of the International Code of Botanical Nomenclature.
(of flat structures, especially leaves) Having both surfaces similar, usually referring to cell types or to the number and distribution of .
with all features morphologically similar, i.e. of similar size and shape. Compare .
yoke-like; describing a structure of paired items joined together as in a or something yoke-like, such as some leaves and fruit.
Leaves formed on a young plant, typically differing from the adult leaves in form.
another term for the kettle-like pitchers of any of the carnivorous pitcher plants, in which they trap their prey.
lipped; where a is divided into two parts, called an upper and lower lip, the two resembling an open mouth with lips.
a thin, plate-like layer. (plural lamellae; adjective lamellate – composed of an assemblage of many layers)
longer than broad, narrowly ovate, broadest in the lower half and tapering to the tip, like a lance or spear head; (sometimes, and incorrectly, used to mean narrowly elliptic).
attached to the side of an organ, e.g. leaves or branches on a stem. For more detail see .
an outgrowth of a stem, usually flat and green; its main function is food manufacture by photosynthesis. Abbreviation: lvs.
Growing on wood tissue after bark as fallen or been stripped off (compare to ).
a woody swelling of the stem below or just above the ground; contains adventitious buds from which new shoots can develop, e.g. after fire.
Very narrow in relation to its length, with the sides mostly parallel. See Leaf shape.
A pod-like fruit that develops constrictions between the segments and at maturity breaks into one-seeded segments instead of splitting open.
Lyre-shaped; deeply lobed, with a large terminal and smaller lateral ones.
Moist, avoiding both extremes of drought and wet; pertaining to conditions of moderate moisture or water supply; applied to organisms (vegetation) occupying moist habitats.
(of vegetation) Of moist habitats and having mostly large and soft leaves.
A plant thriving under intermediate environmental conditions of moderate moisture and temperature, without major seasonal fluctuations.
A single individual that is free from other individuals, not united with them into a group. The term is usually used for pollen to distinguish single grains from or polyads.
Of a group of plants, a comprehensive treatise presenting an analysis and synthesis of taxonomic knowledge of that taxon; the fullest account possible (at the time) of a family, tribe or genus. It is generally worldwide in scope and evaluates all taxonomic treatments of that taxon including studies of its evolutionary relationships with other related taxa, and cytological, genetic, morphological, palaeobotanical and ecological studies. The term is often incorrectly applied to any systematic work devoted to a single taxon. Compare .
Describing a plant, introduced from another region, that grows and reproduces readily in competition with the natural flora.
A usually sweet, nutrient-rich fluid produced by the flowers of many plants and collected by bees and other insects.
(Latin) A conserved name, usually a name that became so much better known than the correct name, that a substitution was made.
A name that is either superfluous at its time of publication because the taxon to which it was applied already has a name, or the name has already been applied to another plant (a homonym).
A name not published in accordance with the , usually without a diagnosis or description of the entity to which it applies, and without reference to either; such a name should not be used.
The naming of things; often restricted to the correct use of scientific names in taxonomy; a system that sets out provisions for the formation and use of names.
Of plants, containing harmful or unwholesome qualities. Applied in conjunction with 'weed' to specifically describe a plant which legislation deems harmful to the environment. Each state and territory in Australia has specific legislation governing noxious weeds.
Stamens are described as numerous when there are more than twice as many as sepals or petals, especially when there is no set number of them. Compare .
(of a leaf ) Broad and notched at the tip; heart-shaped but attached at the pointed end.
Having a length a few times greater than the width, with sides almost parallel and ends rounded.
(of a leaf) Having a length about 1.5 times the width, and widest above the centre.
Blunt or rounded; having converging edges that form an angle of more than 90°. Compare .
The sequence of developmental stages through which an organism passes as it grows.
1.  Describing leaves or flowers borne at the same level but on directly opposite sides of their common .
A group of one or more families sharing common features, ancestry, or both.
Shaped like a section through the long-axis of an egg and attached by the wider end.
Egg-shaped, with wider portion at base; 3-dimensional object, ovate in all sections through long-axis.
Loosely, the seed before fertilization; a structure in a seed plant within which one or more are formed (after fertilization it develops into a seed).
Deeply divided into several lobes arising from more or less the same level.
A versatile ground tissue composed of living primary cells which performs a wide variety of structural and biochemical functions in plants.
Attached to the marginal walls of a structure, e.g. ovules attached to placentas on the wall of the ovary. See placentation.
Having a terminal lobe or , and on either side of it an axis curving outward and backward, bearing lobes or leaflets on the outer side of the curve.
Shield-like, with the stalk attached to the lower surface and not to the .
Hanging, for example an ovule attached to a placenta on the top of the ovary. Compare .
Of an organ that survives vegetatively from season to season. A period of reduced activity between seasons is usual.
With its base wrapped around the stem (so that the stem appears to pass through it), e.g. of leaves and .
A cylinder of parenchyma or sclerenchyma cells that lies just inside the endodermis and is the outer most part of the stele of plants.
2.  In Camellias the final and sepals become indistinguishable and are called perules.
3.  A kind of sac formed by the adherent bases of the two lateral in certain orchids.
Gymnosperms and angiosperms; plants producing stamens and gynoecia; literally plants with conspicuous sexual reproductive organs. Compare cryptogams.
The study of the timing of seasonal biological phenomena, such as flowering, leaf emergence, fruit ripening and leaf fall.
covered with soft, weak, thin and clearly separated hairs, which are usually defined as long and sometimes ascending.
2.  a group of carpels when the carpels are united by the fusion of their walls.
In tracheary elements, a section of the cell wall where the secondary wall is missing, and the primary wall is present. Pits generally occur in pairs and link two cells.
The arrangement of ovules inside ovary; for example axile, free-central, parietal, marginal, basal, or apical.
These rights, governed by Plant Breeder's Rights Acts give the plant breeder legal protection over the propagation of a cultivar, and the exclusive rights to produce and to sell it, including the right to license others to produce and sell plants and reproductive material of a registered, deliberately bred variety. Cf. UPOV.
Governed by the Plant Variety Rights the registration of new varieties is now governed by Plant Breeders Rights.
The part of an embryo that gives rise to the shoot system of a plant. Compare .
powdery mass shed from anthers (of angiosperms) or microsporangia (of gymnosperms); the microspores of seed plants; pollen-grains.
2.  A group of organisms of one species, occupying a defined area and usually isolated to some degree from other similar groups.
3.  In statistics, the whole group of items or individuals under investigation.
A leaf formed at the base of a , usually smaller than those formed later.
In part. In nomenclature, used to denote that the preceding taxon includes more than one currently recognized entity, and that only one of those entities is being considered.
Lying flat on the ground; commonly rooting at nodes that touch the soil surface.
Having male sex organs which mature before the female ones, e.g. a flower shedding pollen before the stigma is receptive. Compare .
A plant, usually flattened and delicate, e.g. in ferns and fern allies.
(from Latin puncta= puncture or prick-mark) marked with an indefinite number of dots, or with similarly small items such as translucent glands or tiny hollows.
(of a growth habit) Conical or pyramid-shaped. Most familiar in some coniferous trees, especially species adapted to snowy climates
of Vachellia karroo bipinnate leaf, with components labelled as follows:
A moist temperate or tropical forest dominated by broad-leaved trees that form a continuous canopy.
2.  recording a new cultivar name with a statutory authority like the Plant Breeder’s Rights Office.
forming a network (or reticulum), e.g. that join one another at more than one point.
rolled under (downward or backward), for example when the edges of leaves are rolled under toward the midrib. Compare .
a perennial underground stem usually growing horizontally. See also . Abbreviation: rhiz.
adj. a plant whose above ground stem is derived from a below ground stem (rhizome). cf. arhizomatous (arhizomatic)
the below-ground surface of plants and adjacent soil as a habitat for microorganisms.
a four-sided figure with opposite sides parallel but with adjacent sides an unequal length (like an oblique rectangle); see also .
a shape, for instance of a leaf, that is roughly diamond-shaped with length equal to width.
outgrowths of the outermost layer of cells just behind the root tips, functioning as water-absorbing organs.
2.  plants selected to produce a root system with some specific attribute, e.g. a virus-free rootstock.
when parts are not whorled or opposite but appear so, due to the contractions of , e.g. the petals in a double rose or a basal cluster of leaves (usually close to the ground) in some plants.
Wrinkled, either covered with wrinkles, or crumpled like a wrinkled leaf, either as a stiffening structure, or in response to disease or insect damage.
Shaped like the head of an arrow; narrow and pointed but gradually enlarged at the base into two straight lobes directed downward; may refer only to the base of a leaf with such lobes. Compare .
Shaped like a salver - Trumpet-shaped; having a long, slender tube and a flat, abruptly expanded limb
2.  A flattened epidermal outgrowth, such as those commonly found on the leaves and rhizomes of ferns.
A strengthening or supporting tissue composed of or of a mixture of sclereids and fibers.
Minute, loose, membranous on the surface of some plant parts, such as leaves.
Chemicals produced by a plant that do not have a role in so-called primary functions such as growth, development, photosynthesis, reproduction, etc.
The tissues concerned with the secretion of gums, resins, oils and other substances in plants.
The category of supplementary taxa intermediate in rank between subgenus and series. It is a singular noun always written with a capital initial letter, in combination with the generic name.
Having all the parts grouped on one side or turned to one side (applied especially to inflorescences).
A part or subdivision of an organ, e.g. a petal is a segment of the corolla. A term sometimes used when the sepals and petals are indistinguishable.
(also selfing) The acceptance by stigmas of pollen from the same flower or from flowers on the same plant, which means they are self-compatible.
with asymmetrical teeth pointing forward; like the cutting edge of a saw.
A tubular or rolled part of an organ, e.g. the lower part of the leaf in most grasses.
Densely covered with fine, soft, straight, hairs, with a lustrous sheen and satiny to the touch.
Single, of flowers that grow one plant per year, one in each axil, or widely separated on the plant; not grouped in an inflorescence.
In a lichen, the structure that bears soredium for non sexual reproduction.
Spoon-shaped; broad at the tip with a narrowed projection extending to the base.
A group, or populations of individuals, sharing common features and/or ancestry, generally the smallest group that can be readily and consistently recognized; often, a group of individuals capable of interbreeding and producing fertile offspring. The basic unit of classification, the category of taxa of the lowest principal rank in the nomenclatural hierarchy. Strict assignment to a species is not always possible, as it is subject to particular contexts, and the species concept under consideration.
Follows the name of the genus, and is the second word of a botanical binomial. The generic name and specific epithet together constitute the name of a species; i.e. the specific epithet is not the species name.
Of arrangement, when plant parts are arranged in a succession of curves like the thread of a screw, or coiled in a cylindrical or conical manner.
A structure in which spores are formed and from which the mature spores are released
A naturally occurring variant of a species, not usually present in a population or group of plants; a plant that has spontaneously mutated so that it differs from its parent plant.
Extending horizontally, e.g. in branches. Standing out at right angles to an axis, e.g. in leaves or hairs.
2.  a conical or tubular outgrowth from the base of a segment, often containing nectar.
The supporting structure of an organ, usually narrower in diameter than the organ itself.
A structure, around the apex of eucalypt, myrtaceae hypanthia, that supports the stamens.
A representative specimen of a or other taxon which demonstrates how the name of that taxon should be used.
The plant , either aerial or subterranean, which bears nodes, leaves, branches, and flowers.
The development or production of fruit that is seedless or has minute seeds because of the abortion of seed development. Compare .
Infertile, as with a that does not bear pollen or a flower that does not bear seed.
Extensive, more or less even cover of a surface, e.g. a lawn grass. Compare .
Any slender organ modified from a stem, leaf, leaflet, or and used by climbing plants to cling to an object.
In groups of three; of leaves, arranged in whorls of three; of a single leaf, having the arranged in groups of three.
Square; having four corners; four-angled, e.g. the cross-sections of stems of herbaceous Lamiaceae.
A sharp, stiff point, usually a modified stem, that cannot be detached without tearing the subtending tissue; a spine. Compare prickle.
1.  Like a trapezium (a four-sided figure with two parallel sides of unequal length).
A woody plant, usually with a single distinct and generally more than 2–3 metres (6.6–9.8 ft) tall.
In non-filamentous plants, any hair-like outgrowth from the , e.g. a hair or bristle; sometimes restricted to unbranched epidermal outgrowths.
(of leaves) Having three main nerves with the lateral nerves arising from the midnerve above the base of the leaf.
More or less triangular in cross-section, but acutely angled (with 3 distinct longitudinal ridges). Compare .
The second word in the two-part scientific name of an organism. Compare .
A compact cluster of flowers or fruits arising from one centre; evident in many rhododendrons.
An alternative name for underground storage organ formed by the swelling of a root; occurs in many orchids.
A dense tuft of vegetation, usually well separated from neighbouring tussocks, for example in some grasses. Compare .
Having leaves arranged in two rows in the same plane, on opposite sides of the branch. See .
An item (usually an specimen) to which the name of a taxon is permanently attached, i.e. a designated representative of a plant name. Important in determining the priority of names available for a particular taxon.
(of sepals and petals in bud) Meeting edge-to-edge but not overlapping.
A plant or group of plants showing some measure of difference from the characteristics associated with a particular .
The arrangement of unexpanded leaves in a ; the order in which leaves unfold from a bud.
In the Compositae, style with sweeping hairs borne on abaxial surfaces of style branches.
A capillary tube formed from a series of open-ended cells in the water-conducting tissue of a plant.
Abounding in or covered with long, soft, straight hairs; shaggy with soft hairs.
1.  Referring to seeds or fruits which germinate before being shed from the parent plant.
A surface covered with small round protuberances, especially in fruit, leaves, twigs and bark. See .
1.  Any plant growing where it is not wanted; commonly associated with disrupted habitats. See also .
1.  A membranous expansion of a fruit or seed which aids in dispersal, for instance on pine seeds.
2.  A thin flange of tissue extending beyond the normal outline of a structure, e.g. on the column of some orchids, on stems, on petioles.
Very densely covered with long, more or less matted or intertwined hairs, resembling a sheep's wool.
A plant with structural features (e.g. hard or succulent leaves) or functional adaptations that prevent water loss by evaporation; usually associated with arid habitats, but not necessarily drought-tolerant. Compare .
A plant generally living in a dry habitat, typically showing xeromorphic or succulent adaptation; a plant able to tolerate long periods of drought. Compare .
Having light and dark circular bands or rings, typically on leaves or flowers.