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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.


Meaning "not enclosed".


Meaning "dwarf", from the Greek "nanos".


Means "dwarf" in Latin.


The term given to the neat striped surface of a lawn after mowing.


Pellets of naphthalene mixed with volatile, scented oils are used sometimes to deter cats and dogs from fouling in the garden.

naphthylacetic acid

This is an active ingredient of some hormone rooting powders and is a type of plant hormone.

narcissus basal rot

Discolouration and rotting occurs through bulb turning them dark brown and dry up.

narcissus bulb fly

Bulbs fail to grow, leaves appear thin and sparse. Flowers do not appear. Maggots eat out centre.

narcissus eelworm

Plants produce stunted or distorted foliage and flower stems.

narcissus fly

An insect pest of Narcissus causing no flowers to be produced, and only weak, grassy leaves. The cut bulbs reveal maggots.

narcissus leaf scorch

Leaves emerge red-brown and scorched. Brown spots appear on foliage and fungal bodies may develop.

narcissus smoulder

Infected bulbs produce deformed, chlorotic shoots with black-brown withered leaf tips. In wet weather may become covered with grey spores.

narcissus viruses

Distinct yellow mottling and streaking on stems and leaves accompanied with distorted size and stunting.


A plant naturally occurring (indigenous) in an area and not introduced from elsewhere.


Generally used to mean things which have not been affected or changed by human intervention.


Thoroughly established in an area, but originally coming from another region.

natural selection

A process whereby organisms most adapted to their environment are more likely to survive and reproduce. In this way the offspring will be more likely to survive and continue the species. Natural selection is an underlying force for the process of evolution.


Boat-shaped, such as the bracts and flowers of some grasses.


Means "cloud-like" in Latin.


Refers to the place where the new growth appears from a bulb.

neck rot (collar rot)

Also called collar rot. Stem base turn brown and rots.


A term meaning the death of plant tissue. "Necrotic spots" would mean that small parts of the plant had died.


A sugary fluid produced by many species of angiosperms, often in the flowers. It is fed on by insects such as butterflies and moths whilst also picking up and depositing pollen enabling pollination. In order to attract insects such flowers are often showy, brightly coloured and fragrant.


Meaning "nectar-bearing" or having nectaries.

nectar robbing

Bees which cannot reach the nectar cut holes in the base of the flower petals.


A gland which gives out a sugary liquid (nectar) and serves to attract insects and some birds which will enable pollination. The nectaries are usually sited at the base of the flower so that the animals will brush against the anthers and styles to facilitate the transfer of pollen. The nectaries are usually sited at the base of the flower so that the animals will brush against the anthers and styles to facilitate the transfer of pollen.

nectria canker

Woody plants appear flaked on areas and white pustules may appear.


Usually refers to the spine-like leaves of pine trees or other conifers; the needles are thin and have a waxy coating to withstand harsh weather.

needle blights and casts of pines

Needles of young trees discolour and may be shed prematurely. Tiny fruiting bodies can be seen on the needles and shoots may die back. The fungi can overwinter on fallen needles.

needle rusts of conifers

Needles become discoloured, may develop orange fungal pustules followed with white spores and fall from tree.


Means "dis-regarded" in Latin.


This is a small worm usually less than a few millimetres long, such as the "chrysanthemum eelworm" and the "stem eelworm" which are plant pests. They may be found in soils, water and animals which feed on plants. Some nematodes can be used for biological control such as those that are parasitic on slugs.

nematode (eelworms)

This is a small worm usually less than a few millimetres long, such as the "chrysanthemum eelworm" and the "stem eelworm" which are plant pests. They may be found in soils, water and animals which feed on plants. Some nematodes can be used for biological control such as those that are parasitic on slugs.


Means "of the woods" in Latin.

Neogene period

A period of time in the Earth's development 2 to 23 million years ago. Flowering plants and mammals were the dominant terrestrial life forms. Large scale earth movements and volcanic activity create many of the current mountain formations.


Prominent veins, eg in a leaf or petal.

net virus

This is a virus which causes damage to the network of veins on a leaf.


Refers to a flower which is sterile since it may have no sexual organs. This is usually a result of hybridisation by humans who wish to create modified flowers for ornamentation such as double flower forms with extra petals.

neutral soil

Used to describe soil with a pH reading around 7.0, which is neither acid nor alkaline. Horticulturists sometimes regard pH readings between 6.5 and 7.5 as neutral.


This is a technique to control bud growth on a tree and may be used as a way of shaping the tree. A nick or small cut can be made into the cambium layer below a bud to inhibit its growth, whereas a nick above the bud will stimulate the bud into growth.


This is used as a pesticide against aphids and other insects. It can be used as a smoke in greenhouses but it must be used with care since it is toxic to humans.


Means "black" in Latin.


Meaning "turning black".


This is another term for 'pinching out'. Nip can also refer to the blackened leaf tips which are the result of frost.


Means "Japanese" in Latin.


This is a chemical compound containing nitrogen (a salt of nitric acid). Nitrates are a component of many fertilizers for supplying the macronutrient nitrogen to plants. Excess nitrates in water run-off into rivers increases the quantities that can enter drinking supplies, where the nitrates and other compounds such as pesticides are pollutants.

nitrate of ammonia

Another name for ammonium nitrate.

nitrate of lime

Another name for calcium nitrate.

nitrate of potash

This is another name for potassium nitrate or saltpetre.

nitrate of soda

Another name for sodium nitrate or nitratine.


Another name for sodium nitrate or nitrate of soda.


This is a chemical compound containing nitrogen (a salt of nitrous acid). However, in the nitrite form the nitrogen is not available for absorption by the plant roots.


A chemical fertilizer composed of ammonium nitrate and calcium carbonate. It supplies nitrogen and is useful for acid soils.


This is a chemical element (symbol N) which as a gas comprises about 80% of the air. It is an essential plant macronutrient (for healthy foliage and other tissues) which can be absorbed by the roots when it is in an available form (nitrates) in the soil solution. If deficient then the plant will suffer a loss of green in the leaves and stunting.

nitrogen cycle

This is a cyclical process in which nitrogen is used by plants, animals and other organisms to build proteins and other compounds in their tissues. It is passed on through the food chain and reused by processes including decomposition, denitrification and nitrogen-fixing.

nitrogen deficiency

Nitrogen is a macronutrient and a shortage will cause all the plant leaves to slowly go pale green then yellow. The plant is slow growing with weak, short new growth and few, if any flowers.


Some plants such as legumes (members of the pea family Leguminosae) can "fix" or add nitrogen compounds to the soil, via nitrogen-fixing bacteria in their root nodules. Nitrogen-fixing is an important part of the nitrogen cycle and makes nitrogen available to the plant for absorption. (In this symbiotic relationship the bacteria receive carbohydrates in return.)


Means "snow white" in Latin.


Means "noble" in Latin.


Refers to organisms which are active at night. This term may refer to flowers that open at night only.


A point on the stem where one or more leaves arise, and also where the branches arise.

no-dig system

A style of cultivation which emphasises natural organic methods with little digging since it is considered that digging breaks down the soil structure, encourages weeds and increases the loss of nutrients from the soil. Mulches may be used and planting is done as close as possible to the surface.


Meaning "knotty". There are other similar terms such as nodular and nodulous which may mean having a knotty appearance as if covered with nodules.


Means "having nodes" in Latin.


A small rounded swelling, as on the roots of members of the pea family (Leguminosae). The nodules of such leguminous plants contain bacteria that can "fix" or incorporate nitrogen from the air into the soil solution (nitrogen-fixing).


Refers to the binomial scientific naming system. There is a botanical convention (International Code of Botanical Nomenclature) that the species name is in lower case and that the binomial name is printed in italics. The botanical convention is that variety or subspecies or form names are in lower case if they are of natural origin, and printed with initial capital letters if they are human-made or cultivars (often the latter is placed in quotes). Nomenclature in this package adheres to the botanical convention, but cultivar names are not placed in quotes since they are distinguished by having initial capital letters and are distinguished clearly in their own box. The other parts of the Latin names are also clearly placed in separate boxes.


Having 9 sets of chromosomes.


Refers to materials that are inorganic. The term is often used to refer to materials manufactured by humans or loosely to food products that have not been produced by organic farming methods.


Refers to a flower that hangs upside-down, possibly because of a bending petiole.


Refers to a plant with no vascular (woody) tissue. For example, algae are non-vascular plants.


Refers to the fruiting shoot of a biennial plant in its second year of growth. A novirame arises from the primocane which is the stem or branch of a biennial plant in its first year of growth.

NPK fertilizer

Refers to the contents of nitrogen, phosphorus and potassium macronutrients. Usually this includes nitrates, phosphates and potash.


This is the parenchymous tissue inside the ovule of a seed plant, and may be used diagnostically to identify the species. The nucellus contains the embryo sac.


Meaning "nut bearing".


Meaning "nut-like".

nuclear stock

This can refer to plants which have been propagated from cuttings and which are known to be free of disease.


The part or organelle of the cell containing the chromosomes.


Means "nude" in Latin.


Means "coin-like" in Latin.


Refers to any place that propagates and grows plants.

nursery bed

Refers to an area of soil reserved for raising seeds and seedlings prior to transferring them to their permanent positions.


A one seeded fruit with a hard (woody) outer covering.


Means "nodding" in Latin.


Generally refers to the macronutrients and micronutrients needed by plants which they usually obtain from the soil via the roots.

nutrient deficiency

The nutrient or nutrients which are lacking could be any of the macronutrients or micronutrients. Often areas between the veins on leaves become yellow, although no distorting of the leaves are obvious.

nutrient film technique

'NFT" is a hydroponic plant growing system, where a solution of plant nutrients flows through a gently sloping tube or gutter in which the plant roots form. This technique has been used in commercial greenhouse tomato and lettuce production. Although NFT requires the management of sophisticated pumping and nutrient dosing equipment, it has advantages of bringing the crop to market more rapidly and may produce more economic crops.


Latin name honouring T.Nuttall.

nut weevil

A pest of nut species where maggots feed in the kernels.


Refers to the young stage of certain insects, such as aphids, where they are mobile, without wings and often of a different colour.

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