Glossary of botanical terms

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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, Glossary of lichen terms, and List of Latin and Greek words commonly used in systematic names.

A

Welwitschia mirabilis presents an example of an acaulescent growth habit

unusual in so large a plant species.

Sandersonia aurantiaca cut open longitudinally to show the androecium, which comprises the anthers surrounding the green central pistil

ab-

Prefix meaning "position away from".^[1]

abaxial

Surface of an organ facing away from the organ's axis, e.g. the lower surface of a lateral organ such as a leaf or petal.^[2] Contrast adaxial.

abort

To abandon development of a structure or organ.^[3]

abscission

Natural shedding of an organ that is mature or aged, as of a ripe fruit or an old leaf.^[4]

abscission zone

Specialized layer of tissue that allows an organ to be shed by abscission when it is ripe or senescent. Such tissue is commonly formed, for example, at the base of a petiole or pedicel.

acaulescent

Having no apparent

Antonym: caulescent

(possessing stem).

accrescent

Increasing in size with age, such as a calyx that continues to grow after the corolla has fallen,^[2] e.g. in Physalis peruviana.

accumbent

Lying against another part of the plant; when applied to a cotyledon, it means that an edge of the cotyledon lies along the folded radicle in the seed.^[8]

-aceae

Suffix added to the word stem of a

Rosa.^[10]

achene

Dry, one-seeded indehiscent fruit^[11] in which the true fruit is not the so-called "berry", but the achenes, which are the so-called "seeds" on the infructescence, e.g. in the genus Fragaria.

acicular

Slender or needle-shaped.^{Leaf shape
.}

acropetal

Moving from roots to leaves, e.g. of molecular signals in plants.

acrophyll

Regular leaves of a mature plant, produced above the base, as opposed to bathyphyll.

acrostichoid

(describing a type of sorus) Covering the entire abaxial surface of a frond, usually densely so, as in Elaphoglossum and Acrostichum.

actino-

Prefix that indicates a radial pattern, form, or morphology.

actinodromous

(of

leaf venation) Palmate or radially arranged venation with three or more primary veins arising at or near the base of the leaf and reaching the margin

in most species, but not all.

actinomorphic

Regular or radially symmetrical;^[12] may be bisected into similar halves in at least two planes. Applies e.g. to steles and flowers in which the perianth segments within each whorl are alike in size and shape. Compare regular. Contrast asymmetrical, irregular, and zygomorphic.

aculeate

Armed with prickles,^[13] e.g. the stem of a rose.

acumen

A long, tapering point, especially the apex of an acuminate leaf.

acuminate

Tapering gradually to a point, with concave sides approaching the point.^{Leaf shape
.}

acute

1. Sharply pointed, but not drawn out, with straight sides approaching the point.^{Leaf shape
.}

2. Converging at an angle of less than 90°. Contrast obtuse.

ad-

Prefix meaning "near or toward"; also meaning "added to".^[13]

adaxial

Surface of an organ facing toward the organ's axis,^[13] e.g. the upper surface of a lateral organ such as a leaf or petal. Contrast abaxial.

adelphia

pl. adelphiae

A bundle or structure of stamens forming one unit in an adelphous flower; for example, the stamen tube around the pistil of Hibiscus.

adelphous

Having organs, particularly filaments such as stamens, connected into one or more adelphiae, whether in the form of bunches or tubes, such as is commonly seen in families such as Malvaceae. Usage of the term is not consistent; some authors include closely bunched filaments, while others include only adelphiae in which filaments are connected minimally at their bases. See, for example, Sims: "...the filaments are so closely pressed that they have the appearance of being monadelphous...".^[14] Compare derived terms such as monadelphous, having stamens growing in a single bunch or tube, for example in Hibiscus, and diadelphous, growing in two bunches.

adherent

Slightly united to an organ of another kind,^[13] usually to a part of another whorl, e.g. a sepal connected to a petal. Contrast adnate.

adnate

Grown from or closely fused to an organ of a different kind,^[13] especially along a margin, e.g. a stamen fused to a petal. Adnate anthers have their halves attached to the filament through most of their length. Contrast connate.

adventitious

Produced in an unpredictable or unusual position,^[13] e.g. an adventitious bud produced from a stem rather than from the more typical axil of a leaf. Adventitious roots may develop from nodes of prostrate stems of some plant species, or from the hypocotyl rather than from the radicle of a germinating monocotyledon.

adventive

Introduced accidentally^[13] (usually referring to a weed).

aerial

Of the air; growing or borne above the surface of the ground or water.^[15]

aestivation

Arrangement of sepals and petals or their lobes in an unexpanded flower bud. Contrast vernation.

aff. (affinis)

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.

aggregate fruit

Cluster of fruits formed from the free carpels of a single flower, e.g. a blackberry. Compare multiple fruit.

agochoric

Plants that are spread through accidental transport.

agricultural weed

See weed.

agriophyte

Plant species that have invaded native vegetation and could survive there without human intervention. They are established there in natural habitats, remaining part of natural vegetation even after human influence has ceased, and are independent of humans in their continued existence.^[16]

agrophic

Comb-like series of veins forking from a single side of a primary or secondary vein.

agrostology

Also graminology.

The scientific study of grasses, in the strictest sense only those species which are members of the family Poaceae. Broader usages sometimes also include grass-like or graminoid species from the families Cyperaceae, Juncaceae, and Typhaceae.

alate

Having a wing or wings.

albumen

Older name for the endosperm of flowering plants. Except for being a storage tissue for nutrients, it is not like the albumen (egg white) of animal embryos.

albuminous

(of seeds) Containing endosperm.

-ales

Suffix added to the stem of a generic name or descriptive name to form the name of a taxonomic order.

alien

Any plant introduced to an area outside its natural range. Often used interchangeably or in combination with foreign, exotic, non-native, and non-indigenous.

alkaloid

Any of a loosely defined class of organic compounds found in the tissues of many species of plants. Alkaloid molecules have one or more alkaline-reacting nitrogen atoms in their carbon structures. Many alkaloids are commercially important as drugs or poisons, e.g. caffeine, morphine, quinine, and strychnine, each of which occurs naturally in certain plants.

allelopathy

The secretion by a plant of biochemicals which influence the growth and reproduction of nearby plants.

allopatric

Having geographically separate, non-overlapping ranges of distribution.^[17] Contrast sympatric.

alternate

1. (adj.) (of leaves or flowers) Borne singly at different levels along a stem, including spiralled parts. Contrast opposite.

2. (prep.) Occurring between something else, e.g. stamens alternating with petals.

alternipetalous

A configuration where parts of the flower, e.g. stamens, alternate in position with the petals.^[18]

ament

A synonym of catkin.

amphitropous

(of an ovule) Bent so that both ends are near each other. Contrast anatropous, campylotropous, and orthotropous.

amplexicaul

With the base dilated and clasping the stem, usually of leaves.

amylum star

a vegetative propagative body filled with starch (amylum) and located around the lower nodes of certain stoneworts.

anastomose

Branching and then rejoining, as with leaf venation.

anastomosis

A connection or fusion of two or more veins that are normally diverging or branching, thereby forming a network.

anatropous

(of an ovule) Inverted so that the micropyle faces the placenta (this is the most common ovule orientation in flowering plants). Contrast amphitropous, campylotropous, and orthotropous.

ancipital

Flat, with two edges (versus round).^[19]

androdioecious

Having bisexual flowers and male flowers on separate individuals. Contrast andromonoecious, polygamodioecious, polygamomonoecious, and polygamous.

androecium

A collective name for the male reproductive parts of a flower; the stamens of a flower considered collectively. Contrast gynoecium. Abbreviated A; e.g. A 3+3 indicates six stamens in two whorls.

androgynophore

A stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth.

androgynous

Having male and female flowers in the same inflorescence.

androphore

The stalk or column supporting the stamens in certain flowers.

andromonoecious

Having bisexual flowers and male flowers on the same individual plant. Contrast androdioecious, gynomonoecious, polygamodioecious, polygamomonoecious, and polygamous.

anemophilous

Adapted to pollination by wind.

anemophily

Adaptation to pollination by wind.

angiosperm

A flowering plant; a plant with developing seeds enclosed in an ovary.

anisomery

The condition of having a floral whorl with a different (usually smaller) number of parts from the other floral whorls.

anisotomic

Branching, with branches having unequal diameters, such as a trunk and its branch. Contrast isotomic.

annual

A plant that completes its life cycle (i.e. germinates, reproduces, and dies) within a single year or growing season.

annulus

1. A ring-like structure; in the form of a ring. Pappus bristles are sometimes attached to a ring called an annulus or disk at the top of the achene beak. In some pollen grains, the exine around the apertures is either thicker or thinner. In pores, this border is termed an annulus. Certain flowers have ring-like constrictions at the mouth of the flower, e.g. in Huernia and Aristolochia.

2. A ring of specialized cells on the sporangium.

Positioned in front of, toward the apex. Compare distal.

anthemoid

In the

Compositae, a style

with a brush-like tuft of sweeping hairs at the tip of each style branch.

anther

The pollen-bearing part of a stamen.

antheridium

in bryophytes, a specialized gametophytic organ that produces the male

gametes

antheridiophore

In liverworts of the order Marchantiales, a male gametophore, a specialized, stalked structure that bears the antheridia.

antherode

A sterile anther of a staminode.

anthesis

1. (of a flower) The period during which pollen is presented and/or the stigma is receptive.

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.

anthocarp

A type of fruit in which some part of the flower persists attached to the pericarp, e.g. in Nyctaginaceae.

anthophore

A stalk-like structure, internode located between the calyx and the other parts of the flower.

anticlinal

Pointing up, away from, or perpendicular to a surface. Contrast periclinal.

antrorse

Directed forward or upward, e.g. of hairs on a stem. Contrast retrorse.

apetalous

Lacking petals.

apex

pl. apices

The tip; the point furthest from the point of attachment.

aphananthous

(of flowers) Inconspicuous or unshowy, as opposed to phaneranthous or showy.

aphlebia

pl. aphlebiae

Imperfect or irregular leaf endings commonly found on ferns and fossils of ferns from the

Carboniferous Period

aphyllous

Leafless; having no leaves.^[20]

apical

At or on the apex of a structure, usually a shoot, a stem, or the trunk of a tree, e.g. an apical meristem or an apical bud.

apiculate

especially of leaves, ending in a short triangular point. See also Leaf shape
.

apiphily

A form of

honey bees

apo-

A prefix meaning "away from, separate, without".

apocarpous

(of a gynoecium) Consisting of one or more carpels which are free from one another (or almost so), e.g. in members of the Ranunculaceae and Dilleniaceae.

apomixis

adj. apomictic

A type of

fertilization

, such that the genetic material they contain is a clone of the parent's genetic material. A plant produced in this way is called an apomict.

apomorphy

innovation) of use in determining membership in a clade

apopetalous

Having separate petals, not fused (sympetalous).

apophyllous

Perianth or other segments free, not united. Compare symphyllous, gamophyllous, and polyphyllous.

apophysis

1. The external part of a cone scale.

2. An outgrowth of an organ or an enlargement of a stem.

appendage

A secondary part attached to a main structure; an external growth that seldom has any obvious function, hence appendiculate.

appendiculate

Having the nature of or bearing appendages.

appressed

Pressed closely but not fused, e.g. leaves against a stem.

aquatic plant

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.

arachnoid

Cobwebby, from being covered with fine white hairs.

arborescent

Tree-like in growth or general appearance.

arboretum

pl. arboreta

A taxonomically arranged collection of trees.

archaeophyte

A non-native plant that has nonetheless been present in a particular geographic area for some time. Contrast neophyte.

archegonium

Plural archegonia.

A multicellular haploid 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.

archegoniophore

In liverworts of the order Marchantiales, a female gametophore: a specialized, stalked structure that bears the archegonia and the sporophytes.

arctotoid

In the

Compositae, a style

with a ring of sweeping hairs borne on the shaft of the style proximal to the style branches.

areolate

Having or being composed of areoles, as an areolate crustose lichen.

areole

1. A space between the threads of a net, e.g. that part of a leaf surface defined by each of the elements of a vein network; as with cacti, the area between the veinlets of a leaf.

2. A structure on the stem

cactus, morphologically a specialised branch; the region of a cactus upon which spines, glochid

s, and flowers are borne.

aril

A membranous or fleshy appendage formed by expansion of the funicle which partly or wholly covers a seed, e.g. the fleshy outer layer of lychee fruit, or that found in members of the Sapindaceae.

aristate

With a stiff, bristle-like

Leaf shape

article

A segment of a jointed stem or of a fruit with constrictions between the seeds; an organ part that separates easily from the rest of the organ at a joint or articulation.

articulate

Jointed; separating freely, leaving a clean scar; e.g. the fronds of certain ferns where they join the rhizome.

ascending

1. (of a stem) Spreading horizontally, then directed upward; an ascending stem is more or less prostrate near its base, then erect.

2. (of an ovule) Attached somewhat above the base.

ascidiate

Shaped like a pitcher, as with the leaves of pitcher plants, e.g. species of Nepenthes and Sarracenia.^[21]

asexual reproduction

Reproduction that does not involve gametes. Often used interchangeably with vegetative reproduction.

asperulous

Having a rough, sandpapery texture; e.g. some leaf surfaces.

asymmetrical

Irregular or unequal; lacking any plane of symmetry; e.g. flowers of Canna.

attenuate

Narrowing gradually. See also Leaf shape
.

auricle

An ear-shaped lobe, particularly a small, roundish, lateral appendage of a leaf or leaf-like organ.

auriculate

Attached at the base with ear-shaped appendages (

Leaf shape

autogamous

Self-pollinating, self-fertilizing – in flowering plants

awn

1. Any long, bristle-like appendage.

2. In the Poaceae, an appendage terminating or on the back of glumes or lemmas of some grass spikelets.

3. In the Geraniaceae, the part of the style that remains attached to the carpel that separates from the carpophore (column).

4. A generally straight, stiff pappus element, varying from stiffly bristle-like to hard and needle-like. In Strophanthus, the awn is the beak of the seed, stipe of the coma hairs.

axil

The upper angle between one part of a plant and another, e.g. the stem and a leaf.

axile

On an axis; of a placenta, on the central axis of the ovary.

axillary

Borne in or arising from the axil, usually referring to the axil of a leaf.

axis

The main stem of a whole plant or inflorescence; also, the line along which this stem extends.