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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.

cabbage aphid

Pest attacking Brassicas where leaves are deformed by sucking aphid, and spreading of viruses.

cabbage maggot (cabbage root fly)

Pest attacking Brassicas where larvae feed on young roots and epidermis of root neck, later destroy the whole root system.

cabbage moth

Caterpillars eat holes in foliage causing plants to wilt.

cabbage root fly

Maggots attack plant roots by eating them and then base of stem. The leaves of affected plants appear to be tinged blue and grow slowly, wilting on sunny days. Young plants can be killed, older plants have their growth restricted. Attacks occur from spring to late summer.

cabbage white butterfly

Scale-like insects stick to undersides of leaves and secrete a sticky excrement. Sooty mould then develop.

cabbage whitefly

Small white insects on undersides of leaves which fly off when disturbed. They excrete a sweet sticky honeydew onto foliage that attracts growths of black sooty mould growths. Light infestations do no permanent damage on strongly growing plants.

cactus

A member of the family Cactaceae, which is usually succulent (with swollen fleshy stems) and spiny. These plants have adapted to growing in arid or semi-arid conditions with water-storing stems and roots.

cactus corky scab

Corky brown markings develop on skin which becomes sunken. Caused by excessive high humidity and light levels.

caducous

Meaning "falling off early".

caeruleus

Means "blue" in Latin.

caesius

Means "blueish grey" in Latin.

caespitosus

Means "tufted" in Latin.

calcareous

Containing calcium carbonate, or chalk, or limestone. May be used to refer to alkaline soils which have formed from or over limestone or chalk.

calcicole

A lime-loving plant which thrives on alkaline soil with a pH reading greater than 7. Such plants can usually only be grown on acid soils with the addition of lime.

calcifuge

A lime-hating plant which will not grow on an alkaline soil. These plants require an acidic pH reading of below 7.

calcium

This is an element (symbol Ca) which is part of the mineral compounds of calcium carbonate (limestone or chalk) or calcium oxide (lime), which is used as a nutrient by plants and is required for healthy tissues. If deficient then the plant may suffer paling of the leaf margins and may lead to necrotic areas. To correct a calcium deficiency the plant may need to be moved to a more chalky soil or possibly manure and lime can be applied. Gypsum is a soft rock which is hydrated calcium sulphate, and can be used to incorporate calcium into the soil to counter a calcium deficiency.

calcium carbonate

Commonly called limestone or chalk. It is also a component of lime which is used to adjust the pH reading of soil and is added as a soil conditioner to clay, to improve structure and drainage. It is used often on vegetable plots to correct growing conditions.

calcium deficiency

Varies with each plant. Calcium deficiency in either soil or compost or lack of moisture content of soil.

calcium nitrate

This is a chemical fertilizer (also called nitrate of lime) which can be used as a top-dressing on acid soils to supply nitrogen. The lime makes the soil less acid and increases the breakdown of organic matter (morhumus) on the soil surface into humus. It may also be used in a spray to counter symptoms of calcium deficiency.

calcium oxide

This is the chemical name for lime.

calcium phosphate

Another name for superphosphate of lime.

calcium sulphate

In its hydrated form this is gypsum.

callus

Hardened plant tissue which forms over a cut or wound and protects the plant from disease infection and loss of fluids.

calomel

Another name for mercurous chloride.

calyx

The sepals collectively; often joined together in a tube called the calyx tube. The calyx surrounds the petals of the flower.

cambium

A meristematic plant tissue, which is capable of cell division. For example, the cork cambium produces cork and the vascular cambium produces xylem and phloem (enabling the plant to grow), giving rise to the annual rings in woody stems.

Cambrian period

A period of time in the Earth's development 505 to 570 million years ago. In addition to early aquatic algae-like plants, animal life including trilobites and molluscs appeared.

cambricus

Means "of Wales" in Latin.

Camellia gall

Large, pale green swellings develop in place of leaves of Camellias. The surface then becomes covered in cream coloured spores.

Camellia yellow mottle

Irregular blotching and mottling of leaves, with bright yellow or near white on dark green surface caused by a viral infection.

campanulate

Bell-shaped; usually referring to the flowers.

campanulatus

Means "bell shaped" in Latin.

campestris

Means "of the plains" in Latin.

candidus

Means "shining white" in Latin.

cane

Refers to an elongated, slender woody stem; generally used to refer to the stems of bamboo, raspberries, blackberries and other hybrid berries.

cane blight

Disease affecting raspberries where leaves wither, dark areas appear on canes at ground level; canes become brittle.

cane midge

Young raspberry canes discolour, splits, cracks and peeling also occurs. When the bark is peeled back tiny pink or red grubs can be seen.

canescens

Means "hoary" in Latin.

cane spot

Disease affecting raspberries where small purple spots appear on canes, eventually turn grey; fruits and leaves spotted later.

canker

Term used to describe a wound on the stem of a tree or shrub, caused by mechanical damage or fungal or bacterial infection. It is usually indicated by swollen bark and, in some cases of disease infection, by a thick sappy ooze.

cantabilis

Means "worthy of song" in Latin.

canus

Means "whiteish grey" in Latin.

capillaris

Means "hair like" in Latin.

capillary

Usually refers to fine hair-like structures in plants (but otherwise it means very thin tubes such as the capillary blood vessels in animals).

capillary action

This is the process by which water moves up through small tubes or pores against gravity, due to surface tension. This is an important component of the forces that enable sap to move up the stems and trunks of plants. Evaporation from the surface of soils causes water to move up from lower levels by capillary action.

capillary matting

This is synthetic fibre mat which is used to draw up water by capillary action, and is used for irrigating pot plants on benches and maintaining humidity around the foliage.

capitate

Collected in a dense cluster or head; usually referring to the shape of an inflorescence or seed head.

capitulum

A head of small stalkless flowers crowded together at the end of the stem in a disc, as in the daisy family.

capping

Refers to the formation of a crust on the surface of soil caused by compaction or water impact.

capsid bug

These are sap-sucking insects which injects a toxin into plant tissues. Damage can appear as the distortion of leaves, flowers or stems and tiny brown spots indicate the points of initial damage.

capsule

A dry fruit, of two or more carpels, which splits open when ripe to disperse the seeds. In bryophytes, it is the spore-containing organ.

Captan

This is a synthetic fungicide which is a component of some hormone rooting powders. It may also be used with gamma BHC formulated as a powder in seed dressings to protect seedlings from damping off and other soil-borne diseases.

Carbaryl

A synthetic insecticide effective against a range of pests including leather-jackets, wire-worms, caterpillars, chafers, ants and also earthworms. Carbaryl is harmful to bees and fish. It is fairly persistent and precautions need to be taken.

carbendazim

This is an active chemical ingredient of some systemic fungicides.

carbohydrates

These are organic compounds of carbon, hydrogen and oxygen which is made in plant cells to provide the energy for growth and cell functions. Carbohydrates are products of photosynthesis and are present in plants in the two main forms of sugar and starch.

carbon

This is a chemical element (symbol C) which together with oxygen makes up carbon dioxide molecules. It is essential for organic life processes, and as a gas it is absorbed by plants for photosynthesis. Carbon is incorporated (synthesised) during metabolism by biochemical processes into compounds such as carbohydrates and proteins.

carbon cycle

This is a cyclical process in which carbon is used by plants, animals and other organisms to build organic compounds in their tissues. The carbon compounds are passed on through the food chain and reused by processes including respiration and decomposition.

carbon dioxide

This is an atmospheric (air) gas (about 0.003% of the atmosphere) which is used by plants to synthesise carbohydrates in their cells by the process of photosynthesis. Carbon dioxide enters the plant primarily through the leaves and is chemically combined with water and energy from the sun using the chlorophyll pigment, producing oxygen gas. (Oxygen gas is consumed by a fire when wood or other organic matter is burned, and carbon dioxide is produced. Growers may increase the amount of carbon dioxide in greenhouses to speed up photosynthesis.)

Carboniferous period

A period of time in the Earth's development 290 to 360 million years ago. Large parts of the world's land surface was covered by forests of early plants with lycopsids (members of the class Lycopsida) dominant. First appearance of conifer-like plants. (Many of the present-day coal reserves were laid down during this period. Carboniferous limestones originated from deposits of the shells and skeletal remains of sea animals.)

carnation tortrix moth

Caterpillars feed on leaves. The leaves are bound together with silk webbing.

carnation wilt

Disease affecting Carnations where leaves yellow.

carneus

Means "flesh pink" in Latin.

carnivorous plants

Refers to plants that obtain all or part of their nutrition from dead animals (mainly small insects) which are killed by the plant's entrapment mechanism (such as Venus fly traps and Pitcher plants) and digested by the secretion of enzymes.

carpel

One of the units of the female part (containing the ovule) of the flower; they are either separate or fused together, developing into a fruit.

carrot aphid

Pest of carrots where damage caused by larvae, heart leaves are curled and the plants stunted.

carrot blight

Disease of carrots where infected places are dark and smelly; disease spreads deeper to kill whole roots.

carrot cavity spot

Spots of discolouration which later develop into cracks and craters beneath carrot root.

carrot fly (carrot rusty fly)

The maggots tunnel into the roots of carrots, parsnips, parsley and celery, especially in the summer period. Protection of the crop may be done by spraying the soil with a solution of pirimiphos-methyl. Onions may be used to intercrop as a further control method.

carrot motley dwarf virus

Foliage develop hues, is stunted or twisted. May not yield edible root.

cartilaginous

Tough and hard.

cascade

Often used to refer to a series of ponds at different levels down which water rapidly falls.

cash crop

A crop that is grown for sale rather than home consumption.

casual

A foreign plant introduced into a country, which appears periodically but cannot maintain itself for long.

catch crop

Refers to a fast growing crop grown between an early harvest and a late sowing of another crop.

caterpillar

General name for the larval stage of butterflies and moths. They can be pests causing severe damage to young leaves, stems and flowers by eating the tissues.

catkin

A crowning spike of tiny flowers, usually hanging and tassel-like. Most catkins use wind pollination.

cats

Soil flower borders and vegetable plots may be damaged while attempting to bury droppings and their urine can scorch foliage. The bark of trees and shrubs can be damaged if cats use them as scratching posts.

caudex

The stem base of a woody plant such as a tree fern or palm.

cauliflorous

Bearing flowers directly from the trunk or branches of the plant, often without stems or leaves.

cauliflory

In angiosperms, it is the continued lateral production of flowers on old woody stems.

cauliflower; blindness

Cauliflowers fail to develop curds. Can be caused by lack of nutrients or over/under watered. It may also be caused in part by pest attacks.

cauliflower; small

Cauliflowers do not grow to healthy normal size. There are many reasons; deficiencies in trace elements, pest or viral attack.

cauline

Can mean "referring to the stem".

Cedar aphid

Foliage become coated with a black sooty mould excreted by aphids. Foliage becomes brown and drops off.

celery leaf miner

Dried up patches of foliage develop after maggots eat interior. Attacks in early summer will damage young plants and attacks from mid summer onwards cause little damage.

celery leaf-spot

Disease where irregular yellow-brown spots appear on leaves; later the leaves die.

cell

Referring to fruit, it is the cavity containing the seeds. A cell is also the fundamental unit of a living organism; plant cells usually have cellulose cell walls and a central aqueous vacuole.

cellulose

This organic compound is an important constituent of plant cell walls. Cellulose is a polymer composed of linked glucose (a type of sugar) molecules. Cellulose helps give plant cells strength and shape, and is a major component of all plant tissues. (It is part of the fibre in a healthy human diet.)

centigrade

A measure of temperature (C) where the freezing point of water is OC (or 32F), and the boiling point is 100C (or 212F).

centimetre

A measure of length (cms) equivalent to 10mm or 0.394 inches.

centipede

This is an arthropod animal which is related to millipedes (which have 2 pairs of legs per segment). Centipedes have long bodies composed of segments, each bearing a pair of legs. Centipedes are generally carnivorous and are not a plant pest.

ceraceus

Means "waxy" in Latin.

cerasus

Means "bearing cherries" in Latin.

cereals

Refers generally to crops such as wheat, oats, and barley which originate from wild grass species.

cernuus

Means "drooping" in Latin.

certified stock and seed

These are plants or seeds which are certified as being free from certain pests and diseases.

chafer grubs

This is an insect which as an adult beetle feeds on the foliage of trees and shrubs. As a larva or grub it can cause serious damage to underground plant organs, such as roots, bulbs and rhizomes.

chalk

This is a soft white rock composed mainly from calcium carbonate giving rise to the development of alkaline soil above.

chamaephyte

Refers to a small, woody plant which overwinters by the formation of buds on the branches which are carried above the ground.

chartaceous

Refers to leaves or flower petals which are thick and paper-like in their texture.

chelated iron

This is a compound where a chemical agent is bound to the iron chemical. A compound such as sequestrene is a formulation of chelated iron and other minerals which may be applied to the soil to correct certain mineral deficiencies.

chemotaxis

The movement of a motile organism, spore or gamate in response to a chemical stimulus.

cherry blackfly

Aphids suck on shoots whose growth is then disordered. With a mass attack the growing points dry.

cherry fruit moth

Small green caterpillars eat buds, flowers and green fruits.

cherry leaf scorch

Fungal disease where leaves become covered with yellow to orange spots; dark fruiting bodies of the fungus on the underside of leaves, spots on fruits, fruit drop.

cherry slugworm

Dry brown patches on cherry leaves are caused by slugworms grazing on upper leaf surface. Leaf can become skeletonised.

Cheshunt compound

This is a fungicide used chiefly for the prevention or control of damping-off disease in seedlings. (It is based on copper sulphate.)

chicken of the woods fungus

Overlapping yellow-orange fungal brackets develop on trunk or large limbs of host trees. Infected wood discolours going from yellowish to brown. Fungal sheets develop causing decay of wood.

chilling

This refers to a cold treatment given to seed, bulbs and other plants prior to germination or forcing. The chilling breaks dormancy and may occur naturally through the winter months or it may also be done artificially in a refrigerator or cold store.

chimaera

An organism with tissues of more than one genotype. It may be produced by mutation or by grafting. Plant chimaeras can produce flowers and foliage of either or both parents as well as intermediate blooms or leaves showing a blend of characteristics. An example would be "Laburnocytisus adamii" which is a chimaera made from a hybrid between "Cytisus purpureus" and "Laburnum anagyroides".

China mark moth

Floating leaves of water lilies and other floating leaves have oval holes. Caused by caterpillars of moth.

chinensis

Means "Chinese" in Latin.

Chironomid midges

Floating leaves of water lilies and other floating leaves appear to have nibbled edges then goes yellow and rot. Caused by maggots of Chironomid midges

chitting

This refers to a pre-germination of seeds before sowing which involves moistening the seed to hydrate its contents and rupture the seed coat. Many seeds can be given this treatment and may produce higher percentage germination with stronger growing seedlings.

chlorine

An element (symbol Cl) which is a micronutrient, needed by plants but only in small quantities. Chlorine is usually present in soil but if deficient then suceptible plants may suffer restricted growth and some wilting of the leaves. To correct a chlorine deficiency, manure or a balanced fertilizer can be used which contains proportions of nitrogen, phosphate and potash (NPK) plus other minor nutrients.

chlorophyll

Green, or blue-green chemical structures (pigments) which enable photosynthesis in autotrophic plants. Plants appear green because the chlorophyll absorbs all the wavelengths (colours) of light apart from green. The chlorophyll is held in the chloroplasts in the plant cells, especially those of the leaves.

chloroplast

An organelle (part of the cell) containing the photosynthetic chlorophyll pigment in eucaryotic plant cells.

chlorosis

A pale appearance to the foliage (low chlorophyll content), caused by deficiency of minerals in the soil, lack of light, or genetic disorder.

Chlorpyrifos

This is an organophosphorus insecticide which can be used for soil pests, including cabbage root flies and other vegetable root flies.

chocolate spot

Disease affecting Broad beans where leaves are blotched with brown and the leaves may die.

chromosome

The organized structures in the cell nucleus, which carry the genes which determine the characteristics of an organism. Each cell of a particular species contain the same number of chromosomes. During normal tissue growth the chromosomes are reproduced during mitosis to retain the number of chromosomes in each of the multiplying cells.

chrysalis

Another name for a pupa.

chrysanthemum eelworm

Pest causing leaves to turn dark brown between the veins; eventually entirely brown.

chrysanthemum leaf miner

Upper surface of leaves appeared raised and scarred with narrow white and later brown wiggly lines.

chrysanthemum petal blight

Red brown spots develop on petals and whole flower starts to decay

chrysanthemum white rust

Raised cream coloured, raised pustules on lower leaf surface. Upper surface has yellow pits. Leaves become distorted and die.

ciliaris

Means "hair fringed" in Latin.

ciliate

Fringed with hairs along the margin, usually of the leaf.

cilium

A short, thread-like locomotary organelle (part of a cell) which beats in a regular manner.

cinereus

Means "ashen grey" in Latin.

circinate

This means coiled or rolled, having the shape of a shepherd's crook like the growing frond of a fern.

cladode

In angiosperms, a short flattened stem of limited growth, replacing the leaves as the site of photosynthesis.

clamp

A name given to a heap of roots or other produce, covered in straw, earth or plastic sheeting to protect it from the weather. A silage clamp is a compressed and protected heap of grass which provides a food store for cattle during the winter.

clasping leaf

Refers to a stalkless leaf that has large basal lobes that appear to clasp the stem.

class

A classification of organisms between division and order.

classification

A way of organising the vast numbers (about 2,000,000) of species of living organisms into groups, so that they can be better described and understood. Similar species are grouped into a genus. Similar genera are grouped into a family. Similar families are grouped into an order. Similar orders are grouped into a class. Similar plant classes are grouped into a division. The plant divisions are grouped into the plant kingdom.

clavate

Meaning "club-shaped".

clavatus

Means "club-shaped" in Latin.

claw

The narrow base of a petal.

clay

This is a general term for soils with particles less than 0.002mm in diameter. A clay soil is one containing more than 25% clay particles. Such soils may be waterlogged in winter and hence are slow to warm up in spring. They are often nutrient-rich and can retain water during periods of drought.

cleaning crop

Refers to a crop that allows thorough weed control and therefore "cleans" the land for future crops of cereals etc.

cleft

May be used to describe a leaf structure which is deeply cut around large lobes which arise from the main vein.

cleistogamous

Referring to flowers which do not open, and become self-pollinating in the bud stage.

Clematis green petal

Flowers open to reveal a green colouration. Caused by adverse growing conditions at a critical stage in the flowers development, particularly a cold spell.

clematis wilt

Disease causing the collapse of mature shoots, usually on young plants.

climate

A general term which refers to the prevailing conditions of temperature, precipitation (rainfall, snow etc), humidity and wind speed of a particular place. Macroclimatic or regional conditions are affected by large-scale factors, such as the latitude, ocean currents etc. Microclimatic conditions are those which affect a small area and is governed by aspect, soil type, vegetation cover etc. A grading of climatic or hardiness zones is used to indicate which plants will grow in each zone.

climatic zone

Refers to a numeric grading (1 to 15) of climates based mainly on temperature ranges, which gives an indication of the hardiness required by a plant to grow successfully.

climber

Any plant that climbs using other plants or objects for support. A variety of methods may be used: "tendril climbers" coil tendrils around objects it touches, "leaf-stalk climbers" coil the leaf-stalk around supports, "root climbers" produce aerial roots that support itself, self-clinging climbers use suckering pads, and "twining climbers" coil the stems.

cloche

Glass or plastic covering to protect plants in the open.

clod

A lump of earth formed from soil particles.

clone

A group of genetically identical plants (or organisms), that have been vegetatively propagated or by tissue-culture. The majority of cultivars are derived from clones and they are normally propagated vegetatively by means such as cuttings.

clove

Refers to a small bulb section which forms part of the larger bulb, such as garlic cloves.

club root

A fungal disease which is prevalent on acid soils. It often affects the roots of brassicas and crucifers causing them to become gnarled and swollen.

cluster cup

Pin-sized spots appear on red coloured swellings that develop on leaves and stems of gooseberries and sedges. Spores are released.

cobalt

An element (symbol Co) which is a micronutrient, needed by plants but only in small quantities. If deficient then susceptible plants may suffer diffuse chlorosis in the leaves. To correct a cobalt deficiency, manure or a balanced fertilizer can be used which contains proportions of nitrogen, phosphate and potash (NPK) plus other minor nutrients.

coccineus

Means "scarlet" in Latin.

coccoid

A growth form of algae where the cells are enveloped in mucilage. For example, this is shown by the Chrysophyta, which are a constituent of phytoplankton.

cockroach

These insects can be a pest in some regions where seedlings in particular are eaten.

cockshafer beetle

These can be a pest on roses, especially prevalent on light soil. The adults fly during early summer, alight on leaves and create irregular shaped holes.

cocoon

A protective outer covering, usually of silk, produced by caterpillars and some other larvae before they turn into pupa.

codling moth

Adult moths appear in early summer and lay eggs on young apples and pears fruitlets, young caterpillars feed on the fruits flesh. Caterpillars tunnel through fruit eating their way out. The grubs depart fruit in late summer. Affected fruits ripen early. Codling moths pupate and overwinter under loose bark.

coeruleus

Means "sky blue" in Latin.

coir

This is composted organic material made from coconut fibre. It is used as a constituent of peat-free compost, as a surface mulch or as a soil conditioner.

cold frame

Refers to a box-like structure with a glass lid used to protect plants from the cold and damp.

cold (or too much water when cold)

Causes disorder of some plants where brown fleshy leaves occur at soil level; usually affects succulents and/or rosette plants.

coleoptile

The sheath around the plumule (growing tip) of grasses and other monocotyledons.

collar

The part of the plant where the stem becomes the root.

collar rot

This is a fungal decay which can appear at the neck of bulbs or at the base (collar) of the plant. Also called neck rot.

colletotrichum

Leaf and stem develop lesions then whole plant dies back.

colonial

A term for a grouping of similar organisms.

Colorado beetles

Foliage of potato, tomato, aubergine, and pepper plants are eaten and destroyed.

column

The fused stalk bearing male and female organs in a flower, found primarily in the orchids; the combination of stamens and stigma.

columnar

Tall and cylindrical or tapering.

comal

Occurring at the tip or apex.

comatus

Means "hairy" in Latin.

combine harvester

A machine that gathers corn (usually by rotating arms at the front) where the stems are cut off, which is then passed over a moving sieve-like system to shake off the ripe ears of corn.

come true

Refers to where seed will germinate and grow to give a plant with the same characteristics as the parent plant.

common grey mould

Fungal disease of strawberries where brown spots on fruits; later whole fruits turn brown with fructiferous covering.

common name

This is the "everyday" name for a plant species. There may be many common names for the same plant, given by people in different regions and countries. An example is the Primrose, or English primrose, whereas this species has only one binomial scientific name or Latin name which is "Primula vulgaris".

communis

Means "living in colonies" in Latin.

comosus

Means "growing in tufts" in Latin.

compaction

The compression and destruction of the soil texture by surface heavy loads, or possibly by cultivation only on one level.

companion planting

This is the close planting of species which are thought to have beneficial affects on each other. For example, some plants may protect others from pest infestion or some plants may release nutrients for other plants.

compatability

Refers to the ability of two plants to cross-fertilize to produce viable seed (able to germinate). It may be for example that a triple cordon apple plant may have 3 different varieties which have been grafted onto the same rootstock; the different varieties being "compatible" for fertilization of the flowers which will then produce fruit.

composite

The type of flower where many small flowers are packed together to give the impression of a single flower, such as members of the daisy family.

compost

A growing medium that can be composed of a variety of materials to try and produce an optimal nutrient and water environment for rooting and growing.

compost heap

A pile of dead and decaying organic material which when decomposed is intended for soil enrichment.

compost too moist (or light or poor)

Can cause "coloured" foliage to gradually become pale green or faded.

compound

Generally refers to molecules and other chemical materials which are made up of many chemical elements (atoms). It also refers to objects made up of more than one part, such as a compound leaf.

compound fertilizer

Usually refers to a balanced fertilizer which contains proportions of nitrogen, phosphate and potash (NPK) which are the 3 main nutrients (macronutrients) needed for plant growth, plus it usually contains other nutrients.

compound leaf

A leaf composed of more than one leaflet.

compressed

Meaning "flattened".

condensation

When the temperature reaches the dew point the high water content in the atmosphere can no longer be held in gaseous form and as the air cools the water vapour turns into a liquid form.

cone

A distinct rounded or elongated structure composed of many overlapping scales which bear pollen or seeds when ripe (sometimes regarded as a type of flower or fruit).

confertus

Means "crowded" in Latin.

congenital

An inherited characteristic which becomes apparent during growth.

conglomeratus

Means "clustered" in Latin.

conical

Cone-shaped.

conifer

Generally referring to a tree which is a member of the order Coniferales. They have needle-like foliage, mostly evergreen and have naked ovules in cones.

conifer aphids

Colonies of insects develop on shoots, branches sometimes trunks. Leaves becomes sticky then a black sooty mould grows. The foliage becomes discoloured or mottled and may drop in severe case; this can happen very rapidly in hot weather. Damage is most apparent on base of tree.

conifer needle rust

Needles become discoloured, and yellow-orange spots appear, causing the needles to be shed.

coniferous boreal

Conifers include pines, spruces, firs, junipers and larches. Most of these trees are evergreen, grow quickly and can tolerate a range of soils, steep slopes and short growing seasons. Coniferous forests are widespread in Scandinavia, mid-Asia and North America. Conifers are often planted to supply timber and wood pulp, since these softwoods generally grow faster than deciduous trees.

conifer red spider mites

Foliage becomes mottled yellow brown in mid-summer and may fall prematurely.

conifer spinning mite

Tiny, yellow-green mites leave foliage of conifers mottled yellow. Dwarf conifers are particularly susceptible.

conservatory

A glazed structure usually housing tender plants and which is used for recreation.

contact treatments

Contact herbicides have an affect directly on the plant tissues sprayed and usually kill a wide spectrum of plants, usually on a short term basis. Contact insecticides have a direct affect on the insect, usually being absorbed through the insect's tracheal (breathing) system.

contiguous

Touching at the edges with no gaps between.

contortus

Means "twisted" in Latin.

contouring

This is a technique of building walls or terraces along the natural contours of the land to provide areas for cultivation, whilst also preventing soil erosion. This technique is useful where there are fragile soils or where there are steep hillsides.

contractile

A term describing stems, roots etc which coil up, usually on drying out of the tissues. Contractile stems can bring seed-bearing structures closer to the soil for dispersal. Contractile roots pull plants back down into the soil.

convar or convarietas

This is a taxon which may be used by some botanical texts, which is larger than a variety but less than a subspecies.

coplanar

In the same plane.

copper

An element (symbol Cu) which is a micronutrient, needed by plants but only in small quantities. If deficient then the plant may suffer a number of symptoms including "summer dieback" of fruits, interveinal crinkling and marginal wilting of leaves. To correct a copper deficiency, manure or a balanced fertilizer can be used which contains proportions of nitrogen, phosphate and potash (NPK) plus other minor nutrients.

copper deficiency

Blue green or yellow discolouration of foliage followed by dieback

copper fungicide

There are various formulations of copper compounds, including copper sulphate and copper oxychloride which are sold as 'copper fungicide' or under brand names. It may be used for similar purposes as other copper sprays, such as Bordeaux mixture.

copper oxychloride

Used as a preventive fungicide to control powdery mildew and also bacterial canker.

copper sulphate

This chemical is an ingredient of some fungicides which may be used in the winter. However, it may scorch foliage in too high concentrations. When mixed with quicklime it is called Bordeaux mixture. It may be called sulphate of copper. When mixed with quicklime it is called Bordeaux mixture. It may be called sulphate of copper.

coppice

To cut back to near ground level each year in order to produce vigorous shoots. This may be for ornamental use or commercially such as for hazel or willow production.

coradial

On the same radius.

coralloid

Coral-like as a result of repeated branching.

coral spot

Common fungal disease where raised orange pustules appear on woody stems.

cordate

Heart-shaped such as in leaf shape.

cordatus

Means "heart shaped" in Latin.

cordon

A trained plant restricted in growth to one main stem or occasionally 2-4 stems (such as apple cordons) often in order to save space.

coriaceous

Having a leathery texture.

coriaceus

Means "tough - leathery" in Latin.

cork

The outer tissue in stems and trunks formed by the cork cambium. It consists of cells which have become "suberized" (impregnated with a waxy substance called suberin) and impervious to water. Cork forms a protective layer against mechanical damage, desiccation, fire and temperature extremes.

corm

A swollen underground stem surrounded by scales (the tunic), and replaced annually by a new corm which forms on top of the original one which then withers away. The corm acts as a food store for when the plant requires rapid growth. There is a bud on the top of the corm from which the roots and leaves appear.

cormel

A small corm arising from the upper surface of a mature corm.

cormlet

A small corm arising at the base of a mature corm.

corn

In Britain this is a term given to any cereal crop. In America "corn" is a name given to maize.

corneus

Means "horny" in Latin.

corolla

The petals collectively; often jointed together into a tube called the corolla tube. The petals and corolla are often brightly coloured to attract pollinators (which are usually insects).

corona

Structures or appendages which stand out from the petals and together form a ring round the centre of the flower. Also known as the crown.

coronarius

Means "crowned" in Latin.

corpus

In angiosperms, the central part of the apex of the stem in which cell divisions occur.

cortex

The tissue of roots and shoots which occurs between the vascular tissue and epidermis.

corymb

A racemose flower cluster in which the inner flower stalks are shorter than the outer, resulting in a flat-topped or rounded head.

corymbose

Having flowers in corymbs.

Cotoneaster webber moths

In early summer stems are covered with silk webbing, leaves dry up and turn brown.

cotyledon

A seed leaf that emerges from a germinating seed, and starts to photosynthesise to produce energy for further growth.

Coumatetralyl

Used in poisoned baits to control pests including mice and rats.

cover crop

This refers to a crop planted between main crops to prevent soil erosion or to provide green manure.

cracking clay

Another name for pelosol soil.

crane flies

Feed on roots and stem bases of small plants. The larvae can cause yellow-brown patches in lawns.

creeper

A plant that grows close to the ground, usually rooting as it spreads.

crenate

Scalloped or toothed with shallow, rounded teeth; usually of a leaf.

crenulate

Minutely crenate; having small scallops around a margin; usually of a leaf.

crest

A tuft of hairs or bristles found on some flowers.

cresylic acid

A powerful sterilizer and fungicide used as a liquid pruning compound or to cure canker on trees.

Cretaceous period

A period of time in the Earth's development 65 to 145 million years ago. Angiosperms (members of the division Angiosperma), which are flowering plants, appeared and became numerous. Chalk deposits formed from the accumulated shells of small aquatic creatures. Many large reptiles (dinosaurs), ammonites and many brachiopod species became extinct possibly because of a cooling of the planet's climate.

crisped

Having a minutely waved edge on petals or leaves.

crispus

Means "curled - wavy" in Latin.

crocks

Pieces of clay flower pots and other materials used to provide some aeration and even drainage over the hole at the bottom of a pot or container.

crome

A gardening implement like a hooked fork, used to break up clods of earth.

crop

Any type of edible, ornamental or useful plant grown for a commercial or domestic purpose.

crop rotation

The growing of crops (vegetables in particular) on a different area of land each year to limit the build-up of pest and disease problems, and to best utilise the soil nutrients. Rotations of 2, 3 or 4 year cycles are common.

cross-fertilizing

This refers to fertilization where the pollen has come from one plant and the fertilized flower has come from another plant.

cross-pollination

This refers to pollination where the pollen has come from one plant and the fertilized flower has come from another plant.

cross-section

Refers to a view of an object when it is apparently cut through.

crown

Structures or appendages which stand out from the petals and together form a ring round the centre of the flower (also known as the corona). Also the crown can refer to the part of the plant found at soil level where new roots and stems arise. The crown can also refer to the top branches of a tree. Also the crown can refer to the part of the plant found at soil level where new roots and stems arise. The crown can also refer to the top branches of a tree.

crown gall

Disease that can affect trees, shrubs and fruit plants where tumours develop on stems and crowns at soil level.

crown rot

Disease affects Rhubarb where buds at the centre of the plant brown and become rotten.

crucifer

A member of the mustard family.

cruentus

Means "blood coloured" in Latin.

crust

Refers to the formation of a hard surface of soil caused by compaction or water impact. The crust is formed by small soil particles filling the spaces in between larger particles. The crust inhibits the drainage of water and can prevent the emergence of seedlings.

cryptophyte

A herbaceous plant which overwinters buds below ground.

cubic centimetre or cc

A measure of capacity (cc) equivalent to 0.001 litre or 0.00176 pints.

cuckoo spit (froghopper)

A common name for a frothy substance which covers the larvae of a small insect pest (froghopper) which sucks the sap of various plants.

cucumber gummosis

Sunken grey-black spots accompanied with a furry, grey mould. Liquid may ooze from lesions.

cucumber mosaic virus

Disease affecting Cucumber and a wide range of plants where irregular mosaic colouring of leaves appear and the plants are stunted.

culinaris

Means "used in cooking" in Latin.

culm

The stem of a bamboo or grass, which is usually hollow.

cultivar

A variety of a plant species produced by mankind. This is a distinct form of a species selected from garden or wild plants and given botanical recognition. It is maintained in cultivation by propagation. There is a botanical convention that variety or subspecies or form names are in lower case if they are of natural origin, and printed with initial capital letters and within single quotation marks if they are human-made or cultivars. Cultivar may be abbreviated to cv or cvs.

cultivator

Generally refers to a powered machine which digs and breaks up the soil.

cuneate

Wedge-shaped.

cuneatus

Means "wedge shaped" in Latin.

curd

Refers to the mass of immature flower buds which make up the heads of cauliflowers and broccoli.

currant blister aphid

Pest affecting red and white currants where upper leaves become twisted, blistered and often tinged red.

currant clearwig moth

Caterpillars tunnel through currants. Shoots may die as stems weakened

currant leaf spot

Brown-black spots develop on leaves, leaves may drop off and fruits shrivel.

cushion scale

Leaves develop sooty mould on upper surface, especially during winter months. Yellow-brown objects are attached to undersides of leaves. Affects camellias, hollies, rhododendrons, evergreen azaleas and euonymus.

cuspidate

Abruptly sharp-pointed.

cuticle

The non-cellular waxy coating of the epidermis of many land plants, which has been secreted onto the surface to reduce water loss.

cutting

A portion of a plant that is removed and used for vegetative propagation. There are a variety of cuttings made: hardwood cuttings, softwood cuttings, semi-ripe cuttings, greenwood cuttings, tip cuttings, root cuttings, basal cuttings, and leaf cuttings.

cutting compost

Refers to any soil or compost which has been prepared for rooting cuttings. Seed and cutting composts usually are moisture-retentive but free-draining and have low nutrient levels to avoid scorching the fine young roots. The rooted plantlets need growing on otherwise they will become straggly and weak.

cutworm

The caterpillar of the turnip moth which feeds at night on stems and leaves. They can cause severe damage, even cutting right through plant tissues at soil level.

cwt or hundred-weight

A measure of weight (cwt) equivalent to 8 stone or 50.8 kilogram.

cyaneus

Means "blue" in Latin.

cycad

A palm-like plant belonging to the family Cycadaceae, which has a long fossil history.

cyme

A broad, more or less flat-topped flower cluster, with the central flowers opening first.

cymose

Having flowers in cymes.

cymose branching

The type of branching in which the apices (plural of apex) abort successively, growth being continued by laterals in each instance.

Cypermethrin

Ingredient of contact insecticides to control ants and some other insects.

Cypress aphid

Sooty moulds develop on foliage and stems produced following sap feeding aphid during summer.

cytokinins

These are plant hormones that control plant cell division. Cytokinins are included in most hormone rooting powders.

cytoplasm

The part of the cell outside the nucleus but inside the cell wall.

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