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Glossary of plant terms

Search our dictionary of 3,300 botanical and plant-related terms – the largest online.
Or browse the descriptions and definitions using the A-Z.


Means "fleshy" in Latin.


This is the leafless pseudobulb of an orchid which is used for food storage. Pseudobulbs provide the food energy to enable production of new bulbs, leaves or flowers.


This refers to the filling of a hole dug for planting, around the roots of a plant. As the planting hole is backfilled, layers of soil should be regularly firmed down (tamping) to ensure that the roots are closely surrounded by soil.


Usually single cell organisms which are not photosynthetic; most are saprophytic. Some bacteria are pathogens of ornamental or crop plants causing a variety of plant diseases.

bacterial canker

A bacterial disease particularly affecting cherries and plums cause the leaves to be full of red holes, stem cankers with oozing gum with general weakening of the plant.

bacterial gall (crown gall)

Leaves turn yellow (those of blue varieties turn red), starting in summer: root development is retarded. This disease affects fruit trees and a wide range of plants.

bacterial soft rot

Areas of the plant become discoloured and as the tissue decays the damaged area often sinks inwards. Infection can spread rapidly if not stopped. Affects a range of roots, tubers, rhizomes and fruits.


This is a name given to a chemical which is used to kill bacteria.

balanced fertilizer

Usually refers to a fertilizer which contains proportions of nitrogen, phosphate and potash (NPK) which are the 3 main nutrients (macronutrients) needed for plant growth (it may also include other nutrients). Sometimes called a compound fertilizer.


Refers to a bundle of plant material, such as a peat bale, hay bale or a straw bale.


A machine that gathers hay, straw or other plant material from the ground and then packs it into bales, usually tied up with string or baler twine.

baler twine

A type of string used by a baler for tying up bales. Baler twine can be made from biodegradable material so that it will pose less of a threat to animals and the environment, and it is sometimes used by growers for tying-in plants.


A disorder of roses where the flower buds fail to open and turns brown then decays (not likely to occur on well-grown rose bushes). It is caused by wet summers. Large, thin-petalled flowers have a tendency to ball.

banded palm thrips

A silvery-brown discolouration of upper leaf surface caused by sap feeding thrips and nymphs.

Banks, Joseph

Joseph Banks (1743-1820) was a notable botanist who travelled the world with James Cook studying new species of plants. (The genus Banksia is named after him.) He helped to establish the Royal Botanical Gardens at Kew, London.


Means "bearded" in Latin.

bare-root plant

This refers to plants sold without soil around their roots. The soil may have been washed off to limit the spread of soil-borne diseases and pests. Such plants need to be planted carefully with moist soil closely pushed around the roots to encourage the growth of fibrous roots that will nourish the plant.


The protective outer coating of the woody stems, branches and trunks of woody plants. The bark consists of dead cells originating from the vascular cambium layer (which is underneath the bark). As new inner bark is added, the bark on the outside has to stretch and split to allow for the extra girth.

bark beetles

If plants are in bad health they are more susceptible. Larvae feed between the bark and wood and eat out channels.


This is the process of removing a ring of bark from around a stem or branch. This is done to reduce vigorous growth and to encourage the formation of fruit in some trees. If bark-ringing happens on the main stem or trunk (for example by grazing animals) the lack of sugar transport down to the roots by the underlying phloem probably results in the death of the plant.


Refers to a soil in which nothing grows, possibly because there are no nutrients present.

basal cutting

A portion of a plant that is removed and used for vegetative propagation: basal cuttings are taken from the base of a plant (which is usually herbaceous) as it begins to produce growth in spring.

basal plate

This refers to the base of a bulb from which the roots, leaves and stems grow. Bulbils may also form from this tissue. The basal plate needs to be in a healthy condition if a new plant is to be successfully grown.

basal rot

Disease mainly affecting lilies (Narcissus) causing stunted growth and root/bulb decay.

base dressing

This refers to a certain amount of fertilizer or organic matter which is applied to the soil before planting. This base provides nutrients for the initial 6-8 weeks, after which further fertilizer may be needed.

basic slag

This is the waste product from making steel, and contains calcium phosphate which is a source of phosphate for a fertilizer.


Means "royal" in Latin.

basin irrigation

This is a style of irrigation where a shallow depression is made around a plant base which is then filled with water to allow it to soak into the soil. Care should be taken not to damage any fibrous roots just below the surface of the soil, and also care should be taken not to pile up soil next to the stem which may cause rotting.

bay sucker

Leaves at tips develop thick, pale yellow margins which curl over and turn brown. Sap-feeding, aphid-like, grey insects which secrete a white, waxy substance from their bodies causing damage

bean anthracnose

Sunken brown marks develop on stems. Pods develop a red-brown spotting. Leaf veins may turn red-brown then die off. During wet weather, a pink coloured slimy fungal growth may develop.

bean chocolate spot

Chocolate brown spots and streaks appear all over plant. Severely affected plants may die.

bean halo blight

Appear water-soaked then darkening, each one surrounded by a bright yellow 'halo'. Leaves develop yellowing then may die. Growth is stunted and yields reduced. Pods and stems develop grey patched if infected.

bean mosaic virus

Mottled dark green or yellow patches on leaves, they also crinkle. Plants and pods may be distorted and stunted. Plants may collapse.

bean seed beetles

Beetles burrow through dry beans and peas kept for seed.

bean seed fly

Seeds are eaten by larvae. Seedlings are usually killed before shoots get a chance to emerge. Slow germinating seeds are usually more at risk


Having long or stiff hairs.

bedding plant

A plant used for temporary garden display. Usually annuals, biennials and tender perennials are used. Bedding plants may be grown under glass from seed or cuttings, then hardened off for planting in the beds in spring ready for the summer display.

bed system

This is a method of growing crops in blocks allowing easy access around the outside to limit soil compaction. A bed system allows the rotation of crops with each bed having a different crop, and limiting the transfer of pests and diseases.


Solitary bees excavate burrows. They look like bumble bees but do not sting. No plants are seriously affected.

beech bark disease

Areas of bark may die. May exude a black tar-like substance. Leaves become yellowed, newly produced leaves are small and yellow and small red fungal bodies develop on affected bark.

beech bark scale

White powdery substance appears in crevices in bark, especially on trunk and larger branches.

beech gall mite

Yellow-brown galls develop on upper surfaces of beech leaves.

beech leaf mining weevil

In spring foliage develops many small, round holes. Trees become abundant with weevils.

beech woolly aphid

Aphids form dense colonies on shoot tips and underside of leaves.

beefsteak fungus

Weakens the wood of Oak and other trees, making it brittle. Soft cream coloured bracket fungus often growing singly about 5-25cm across, develop on branches and tree trunks between summer and autumn. The fungus feeds on the wood which develops the 'brown oak' streaky brown colouring, which leads to cracking up the wood surface.


An insect which belongs to the very large beetle family, which has many species including those that are plant feeding, scavenging, wood-eating, carnivorous, flying and water-dwelling. Some beetles are pests, and their larvae may cause damage to ornamental and vegetable crops. Some beetles are vectors of other diseases such as the so called Dutch Elm Disease.

beet leaf miner

Leaves develop large, brown areas. White maggots eat internal tissue of beetroot and spinach.

beetle (raspberry beetle)

The larvae of the beetles are white maggots which feed inside the fruits of raspberries and blackberries.

Begonia powdery mildew

Grey-white powdery growth appears on leaves which become dried, brown or yellowed and soggy

begonia tuber rot

A softening of the tuber and skin rot which may be countered by storing in warmer, frost-free places.


Means "beautiful" in Latin.


A contact insecticide often used for ants, wasp nests, woodlice and earwigs.

beneficial insect

This refers to any insect which aids pollination, or which is a predator or parasite on a plant pest.


A fungicide used to control a range of fungal diseases. However, this is generally no longer approved for public use and may be banned in some countries.


This is a systemic organic fungicide which is active against a wide range of fungal diseases. It has been in use for over 30 years and a number of fungi have developed some resistance to it. Benomyl is generally no longer approved for public use and may be banned in some countries.


A fleshy rounded fruit usually with hard pips or seeds. Botanically, a berry is a many-seeded fruit with a fleshy pericarp, produced from a single flower. Examples are the grape, gooseberry and current. The berry may be eaten by a bird or other animal, and later deposited whereupon germination can occur. (The pulp may contain a chemical inhibitor which prevents the seeds from germinating until the pulp has been broken down, and then enabling the seeds to take up water.)


Having two colours, such as the leaf surfaces being substantially different in colour.


A plant which grows and develops in the first year, and fruits and seeds in the second. Biennials are sown and germinate in their first season and make a resting bud where they survive the winter. In the following spring top growth starts again and flowers are then produced.


Contact insecticide used against a wide range of insects such as beetles.


Divided deeply into two as far as the middle.


Having two leaves on each leaf stalk or petiole.


Contact insecticide used against a wide range of insects such as beetles.


Divided into two equal branches (arising from the same point).

big bud

This an abnormal condition of buds where they are unusually swollen and sometimes split since they are infested with mite pests (big bud mite). These buds will not be able to develop correctly into leaves, stems and flowers. Removing infected buds may be partially successful but total control is difficult.

big bud mite

An insect pest that causes the condition known as big bud.

Big vein

Lettuce leaf veins are yellow and swollen. appearing puckered and blistered.

binomial scientific name

A species is named by using the genus name and the species name together to form a two part name such as "Primula vulgaris" (whereas the common name would be the Primrose). In this way a plant or animal (or other organism) can be precisely identified whereas there may be several common names for the same organism. There is a botanical convention for nomenclature. This is sometimes called the Latin name, since the names come from the Latin language.


Often used in conjunction with Permethrin as a contact insecticide.


Chemicals used in biological processes.


Refers to the ability to be broken down by organisms such as bacteria. For example baler twine can be made from biodegradable material, as can plastic bags, detergents and other potential pollutants.


Refers to the range of plant, animal and other species living in an environment or habitat. An ecosystem generally is more stable and able to withstand adverse influences, the richer its biodiversity. There are about 2,000,000 different species of organisms on the planet many of which are poorly understood, and mankind needs to try to appreciate their characteristics and inter-relationships before destroying them or their habitats. For example, important medical drugs and other chemical compounds can be supplied from sometimes obscure species, and wild varieties of crop plants often have genetic resistance to important diseases.

biological control

This control of pests does not involve the use of chemicals, but rather the use of natural means such as insect predators on a pest organism. Examples are the use of ladybirds on aphids in greenhouses, the use of fungal diseases which affect the pests such as locusts, nematode worms which are parasitic on slugs, or mites which feed on plant-eating larvae.


This is a synthetic insecticide which is used for general control against a wide range of insect pests. It is a relatively safe chemical for use on edible crops.


Refers to a genetically fixed variant of a taxon which is particularly adapted to some (usually environmental) condition.


Divided very deeply into two (to below the middle).


A pinnate leaf in which the leaflets are also pinnate.

birch witches' brooms

Branches cluster together (Can be mistaken for birds nests), leaves turn yellow and bear a layer of fungal spores on lower surface.

bird-seed alien

An alien plant introduced accidentally as part of bird-seed.

birds (sparrows, bullfinches, pigeons etc)

These can be pests since fruits are pecked or wholly eaten On lawns they are only a nuisance when lawns are being sown since they eat the seeds, but they also eat lawn pests.


Both male and female organs are in the same flower. Also referred to as hermaphrodite.

bitter pit

This is a disorder of apples where the flesh of the fruit is marked with brown spots.

bitter rot

Fruits of apples and quinces spotted dark brown; flesh affected too. Tiny fungal pustules may be seen.

black bean aphid

Insects mass on shoot tips and undersides of leaves.

blackberry cane spot

Silver grey and purple spots appear on canes. Black fungal spot develop in centre.

blackcurrant gall midge

Leaves remain crumpled then die. White maggots secrete chemicals which cause damage.


This is the common name for a form of aphid which is a pest of a number of plants. The insect feeds by a pointed mouthpart called a stylet which is inserted into the plant tissues to suck up sap.


This is a disease caused by a fungus or by bacteria which can kill plants such as pelargonium cuttings and some bedded out plants.

black rot

A disease particularly affecting turnips and swedes where leaf edges yellow with black veins and the sliced root is black round perimeter.

black slime

Disease often affecting Hyacinths where leaves turn yellow and collapse. Black resting bodies found between outer scales of bulb.


Disease often affecting roses where leaves develop black or brownish fringed spots on leaves; in a severe attack leaves will drop.


The flattened part of an organ, such as a leaf or petal. Also called a lamina.


When sunlight is excluded from leaves or stems by covering with a flowerpot or other device, the plant does not develop a green colour and the tissues remain tender.


Means "pleasing" in Latin.


When a stem, leaf or root is cut, the end may excude plant sap until a callus is formed which seals the wound.

bleeding canker

Yellow or brown substance oozes from patches of dead or dying bark making susceptible to other disease.


This term may be given to a pest or disease which causes withering in plant tissues without rotting.

blight of onions (mould of onion)

Fungal disease where pale yellow spots form on onion leaves and flower stems, later a grey covering of mould; the attacked tissue dies,


This is a failure to flower which may be caused by an infestation by a pest or infection by a disease. It may also be caused by incorrect growing conditions. It may also be caused by incorrect growing conditions.

blindness of bulbs

Flowering is poor or even non-existent. Buds may be produced but they are dry and empty although leaves appear healthy. This problem is common the year after a dry, hot summer.

blind shoots

Disorder that may affect Narcissus where leaves produced but flowers fail to appear.

blood, fish and bone

This is a general fertilizer which is made from ground fish and waste from the meat industry. It is a source of nitrogen and phosphorous.


A flower or blossom. Also a fine, waxy coating on stems, leaves or fruits (also called the cuticle).


This term describes a flower or group of flowers, and usually refers to the flowers of an edible fruit species, such as cherry blossom.

blossom end rot

Disorder affecting tomatoes where black, sunken areas appear on undersides of fruits.

blossom weevil

A pest particularly of strawberries and apples where grubs destroy blossoms. Unopened flowers wither and turn brown; stalks eaten through.

blossom wilt

Disease affecting apple, pear, cherry, plums. The flowers wilt and turn brown; leaves may die.

blotchy ripening

Disorder affecting tomatoes where fruits ripen unevenly.

bluebell rust

Dark brown fungal pustules develop on leaves which wither away.

blue mould on bulbs

Bulbs and corms in store covered in blue-green fungal growth. In extreme cases decay may set in but often the damage is restricted to sunken patches on surface. Mildly affected bulbs and corms may grow normally when planted.

blushing bracket

Semi-circular brownish rubbery bracket fungus appear mainly in autumn, weakening the wood.

bog garden

An area where the soil is kept permanently damp (but not waterlogged).

bog plant

Plant species which have evolved to grow in permanently damp soil, which is often fairly acidic soil. Such plants will usually wilt rapidly if the soil dries out.


The trunk of a tree from ground level to the first major branch.


Producing flowers and seed prematurely, such as in the case of vegetables like lettuce and beetroot. This is often a problem in vegetable crops that are grown from their compact heads of leaves. Bolting can be caused by sowing the plants too early or late in the season. If the plants experience poor growing conditions such as dry roots the plants may bolt or run to seed, which is a survival strategy in case the plant dies.


This is plant fertilizer made from ground bones. It contains a large amount of phosphate which generally encourages good root growth.


A Japanese cultivation method of producing dwarf trees or shrubs by techniques such as; pruning roots, keeping them in small shallow containers, pinching out shoots, removing growth buds and training stems/branches with wire.


This is a naturally occurring mineral which may be used as a fertilizer to correct minor boron deficiencies. It may also be used in poisoned bait to control ants and some other insects.

Bordeaux mixture

This is a mixture of equal parts of copper sulphate and quicklime, which is used as a fungicide.


Means "northern" in Latin.


An element (symbol B) which is a micronutrient, needed by plants but only in small quantities. If deficient then the plant may suffer a number of symptoms including "stem crack" of celery, "heart rot" of sugar beet, and "hard fruit" of citrus.

boron deficiency

Varies with each crop. Affects beetroot, turnip, carrot, radish, and swede. Occasionally cauliflowers, cabbages, celery, pears and strawberries. To correct a boron deficiency, manure or a balanced fertilizer can be used which contains proportions of nitrogen, phosphate and potash (NPK) plus other minor nutrients. Borax may be used as a fertilizer to correct minor boron deficiencies.


Refers to the study of plants (botany).


A person who studies botany, which concerns the morphology, nomenclature and ecology of plants. Notable historical botanists and naturalists are Linnaeus, Banks and Darwin.


The study of plants; it can also be extended to their importance and use by humans and other organisms.

botrytis (grey mould)

This is a grey mould fungal disease that causes the rotting of young and soft plant tissues, usually leading to the plant death. Botrytis can spread to other plants via the soil or dirty seed trays.

bottom heat

This refers to the heat given to the bottom of seed trays to encourage germination of seeds or the rooting of cuttings. Some studies have shown that bottom heat is more important than air temperature for the successful rooting of cuttings.

box sucker

Box shoots are stunted. Nymphs of sap-feeding insect attack new growth.

bracket fungus

Fungal, woody-looking, crusty growths with purple undersides develop on large limbs or main trunk of affected trees, particularly on the base. They cause damage to wood tissues and trees become weakened. Branches appear dead and thinning of the crown.


A little leaf or scale-like structure, often with a flower in its axil.

bracteolated curds

Cauliflowers leaves grow out of curds. Curds may still be eaten.


A reduced leaf produced on a flower stalk or pedicel in angiosperms.

bract scale

In gymnosperms, the scale (in some species becoming woody) in the female cone. (In the axis of the bract scale arises the ovuliferous scale on which the ovules develop.)


Refers generally to the shoot of a plant, usually the secondary shoots off the main stem or trunk. It can be used loosely to describe any division, such as "branching veins" in the leaf.


A plant that is a member of the cabbage family (Brassicaceae or Cruciferae).

brassica bacteria soft rot

Patches of foliage or other areas of plant discolour; disintegration follows bringing a foul smell.

brassica dark leaf spot

Brownish grey round spots develop on leaves each with rings of fungus. May cause holes in leaves.

brassica downy mildew

Yellow blotches appear on upper leaf surfaces and below on under side a grey-white, fungal growth. A severe attack may cause the death of seedlings.

brassica light leaf spot

Leaves become covered in whiteish fungal growth and spots may merge.

brassica ring spot

Dark purple spots with yellow edges appear on leaves, older leaves being more susceptible. Black fungal bodies may be visible

brassica wire stem

Leaves become yellowed and narrowed or may die back. Usually caused by a deficiency of molybdenum.


This may refer to leaf or stem growth which is produced from an axillary bud. This term may also refer to the unexpected flower colour caused by a mutation or hybridisation.

break crop

Refers to any crop which is grown for one season to give the land a rest from its usual crop/s.


This is the common name for wild roses which may be used as rootstocks for cultivated varieties.


Stiff hair or soft, flexible spine.


Refers to the act of spreading seed or fertilizer even over an area.


Refers to trees and shrubs which have flat leaves, unlike the needle-like leaves of conifers. The term "broad-leaved weeds" may be used to distinguish plants such as dandelions and daisies which grow in grass lawns.

broad-leaved evergreen

The term broad-leaved often refers to deciduous trees, but there are many evergreen non-coniferous trees such as members of the rhododendrons. For example, parts of eastern China and south eastern USA have natural woodlands of broad-leaved evergreens mixed in with other trees.

broad spectrum

Refers to a chemical pesticide which can be used on a wide range of pests. It may also refer to certain electric lights which produce a wide range of wavelengths and can be used to imitate daylight.


An active ingredient of some pesticides such as those for killing mice.


Used for soil application, it is an insecticide for controlling insects such as wireworms and chafer larvae.

broom gall mite

Disease affecting broom where green or grey brown, lumpy outgrowths appear on stems.

brown core of Primulas

Leaves may be yellowed and generally plants show poor signs of growth. They wilt and die quickly. Caused by the fungus 'Phytophthora primulae', which is soil-borne.

brown heart

Disorder affecting turnips and swedes which when sliced open, roots reveal brown centre.

brown rot

Disease affecting apple, pear, plum, cherry where fruits become brown and rotten, developing concentric rings of buff pustules.

brown rot and spur canker of apple

Fungal disease affecting apples where concentric cushions of spore cases appear on fruit.

brown scale

Pest attacking peach, grape and gooseberry where stems are covered with small, brown, limpet-like scales.

brown tail moth

Caterpillars feed on plants leaving them covered in webbing 'tents'. Affects hawthorne, cherry, apple, blackthorn, blackberry, rose and other trees and shrubs.

Bryobia mites

Leaves develop a mottling on upper surface of ivies, primulas, polyanthus and gooseberries


Plants belong to the division Bryophta, and include mosses and liverworts.

buckeye rot

Disease affecting tomatoes where grey or reddish areas appear on fruit, overlaid with brown concentric rings.


The apical meristem (growing point) of a stem, surrounded by leaf primordia and sometimes enclosed in scale leaves. Fruit buds develop into flowers then fruits, whereas wood buds develop into shoots.

bud blast

Disease affecting rhododendrons where buds turn brown, developing black pinhead spore capsules and failing to open.


This is a form of grafting where a bud from one woody species is grafted onto the rootstock of another.

bud drop

A disorder which may result in the loss of the leaf or flower buds, and may be caused by drought at the roots.

bud dry or failure

Small hard buds remain on the plants but fail to develop fully and do not open. This is usually the result of unsuitable conditions; frost, dry soil or malnutrition are often to blame.

bud scale mite

Mites feed on bulbs of Daffodil and Amaryllis bulbs therefore stunting them.


The scales enclosing a bud before it expands.

buff-tip moth

The caterpillars defoliate plants. Only harmful to young trees or shrubs of lime, oak, hornbeam, birch, rose, cherry.


A swollen underground bud-like structure remaining dormant below ground during unfavourable growth periods, and acting as a food store for when the plant requires rapid growth.


A small bulb or tuber, often arising from the axil of a leaf; it can be used for reproducing the plant. The bulbil may drop off and grow into a new plant.


A small bulb produced at the base of a mature one.


Means "swollen like a bulb" in Latin.

bulb scale mite

Pest attacking in particular Narcissus bulbs in store which become soft, lightweight and brown; when sliced open specks are visible in tissue.


Blistered or puckered.


Means "blistered" in Latin.


Used as a fungicide (often with triforine) against a range of fungal diseases.


A spiny or prickly fruit, or cluster of fruits (with hooks adapted to catch in the hair or feathers of animals for distribution). Also a burr is a woody outgrowth on the stems of certain trees which is undifferentiated growth resulting in swirls of woody tissues, which are prized by woodcarvers for their decorative effects.


A general term for a shrub with a rounded shape.


May be used to control aphids and some other insects in pot plants.


Means "box leaved" in Latin.

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