of interior landscaping terminology
Included here are definitions of the more commonly
found abbreviations and words used in the interior
ACOP Approved Code Of Practice
American Institute of Architects
ALCA American Landscape Contractors’ Association
BALI British Association of Landscape Industries
BASIS British Agrochemical Standards Inspection
BPCA British Pest Control Association
BS British Standard
BSI British Standards Institute
CCW Countryside Council for Wales (formerly NCC)
CITES Convention on International Trade in Endangered
COPR Control of Pesticides Regulations
COSHH Control of Substances Hazardous to Health
Continuing Professional Development
(UK) Department of the Environment, Food and Rural
European Federation of Interior-landscaping Groups
EHO Environmental Health Officer
EN English Nature (formerly NCC)
FEPA Food and Environment Protection Act
GRP Glass Reinforced Plastic (often known as fibreglass)
HASWA Health And Safety At Work Act
HSE Health and Safety Executive
ILG Interior Landscape Group (of BALI (q.v.))
ISO International Standards Organisation
LD50 Lethal Dose 50%
LECA Light Expanded Clay Aggregate
MEL Maximum Exposure Limit
MEWP Mobile Elevating Work Platform
mg/kg (or mg.kg-1) Milligrammes per Kilogramme
NCC Nature Conservancy Council (see CCW, EN &
NPK Nitrogen, Phosphorus, Potassium
NPTC National Proficiency Test Certificate
OES Occupational Exposure Standard
PPE Personal Protective Equipment
ppm Parts Per Million
%RH Percent Relative Humidity
Royal Institute of British Architects
RIDDOR Reporting of Injuries, Diseases and Dangerous
RoSPA Royal Society for the Prevention of Accidents
RPE Respiratory Protective Equipment
SBS Sick Building Syndrome
SDS Safety Data Sheet
SNH Scottish Natural Heritage (formerly NCC)
sp Species (singular)
spp Species (plural)
SWL Safe Working Load
ULV Ultra-Low Volume
ABSCISSION The controlled shedding of part of
a plant e.g. separation of leaves from the stem.
ABSCISSION LAYER A thin plate of cells which forms
at the point of abscission (q.v.).
ACID Refers to a material, e.g. soil, water, with
a pH level below 7.0.
ACCIDENT An unforeseen occurrence which results
in injury to persons or damage to property.
ACUMINATE Tapering to a slender point.
ACTIVE INGREDIENT A chemical ingredient from which
preparations are formulated, e.g. Deltamethrin
ADVENTITIOUS Plant growth occurring in an unusual
position e.g. aerial roots (q.v.).
AERIAL ROOT A root that arises above soil level
e.g. as in Monstera deliciosa.
AEROBIC Living or functioning only in the presence
AIR FILLED POROSITY The proportion of the volume
of a growing medium that contains air after it
has been saturated with water and allowed to drain.
ALKALINE Refers to a material, e.g. soil, water,
with a pH level above 7.0.
ALTERNATE A form of leaf arrangement in which
there is one leaf at each node (q.v.), giving
a staggered formation up the plant stem.
ANAEROBIC Living or functioning in the absence
of free oxygen.
ANNUAL RING The growth produced by the stem of
a woody plant in a single year. In transverse
section, it is often possible to distinguish the
separate “rings”, providing an easy
method of ageing the plant.
ANNUAL A plant that germinates, blooms then dies
within a single year.
APICAL At the tip of a branch or stem.
ARISTATE Bearing thistles, often to the extent
of appearing bearded.
ASYMMETRICAL LEAF A lop-sided leaf with one half
larger than the other.
AURICULATE Having ear-shaped lobes at the base
of the leaf.
ANTHER The male part of the flower that produces
AUTOTROPHIC The ability to produce complex organic
substances from simple inorganic compounds e.g.
as in most plants.
AXIL The angle between the upper surface of a
leaf or leaf stalk and the stem that carries it.
AXILLARY BUD New shoots or flowers growing from
the axil (q.v.).
BALI British Association of Landscape Industries.
BARK The protective layer of plant tissue that
grows around the cambium (q.v.). Used as a decorative
mulch (q.v.) when chipped or as a compost additive
when partially decomposed.
BASIDIOMYCETES A group of higher fungi that includes
most of the wood-rotting species. Can cause damage
to the roots of containerised plants, especially
if over-watered and bark mulch gets mixed into
BIANNUAL Growing twice a year.
BIENNIAL A plant which germinates one year and
flowers, produces seed and dies the next, thereby
completing a two-year life cycle.
BIOLOGICAL CONTROL AGENTS Parasites, predators,
viruses, bacteria and fungi. Widely used in horticulture
to control pests.
BIP Abbreviated term used for Philodendron bipinnatifidum.
BIPINNATE Describing a compound leaf with two
rows of leaflets (pinnae) which are themselves
divided into even smaller segments.
BLADE The main expanded part of a leaf as distinct
from its stalk. Also called the lamina (q.v.).
BLOOM A delicate powdery or waxy coating found
on some leaves and fruits e.g. the silvery “frosting”
on Aechmea fasciata leaves.
BONSAI The art of dwarfing trees by root restriction
BRACT A modified leaf, often part of a flower,
which may be either leaf-like or petal-like, and
is sometimes highly coloured e.g. Poinsettia.
BREAK The side shoot that forms after removal
of the growing point.
BUD A shoot in embryonic form containing a miniature
stem, leaf or flower.
BULK DENSITY The dry mass per unit volume of moist
CAMBIUM The area of plant tissue, usually just
below the bark, that is responsible for producing
CAPILLARY ACTION The natural upward movement of
water and other liquids in confined spaces e.g.
plant cells, spaces between soil particles.
CAPITULUM A cluster of tiny florets (q.v.) that
looks like a single bloom e.g. members of the
CARBON CYCLE The circulation of carbon between
living organisations and the environment.
CARNIVOROUS PLANT A plant that is adapted to obtain
food by digesting insects and other small animals,
in addition to photosynthesis. Also called “insectivorous”.
CAROTENOID A yellow, orange or brown pigment found
in leaves, fruit and flowers. Contributes to the
autumn colours in deciduous leaves.
CELLULOSE A carbohydrate forming the main constituent
of plant-cell walls.
CHLOROSIS Abnormal yellowing or blanching of leaves,
usually through lack of chlorophyll or essential
CHLOROPHYLL A pigment in the green parts of plants
involved in the light reactions of photosynthesis
CHLOROPLAST The chlorophyll-containing structures
within the green parts of a plant.
CILIATE Describing leaves, bracts or petals that
are fringed with fine hairs.
CLADODE A flattened stem resembling and performing
the functions of a leaf.
CLASS The group of plants on the next rank below
a division or phylum (q.v.).
COIR Fibre derived from the outer husk of coconuts
which, when partially decomposed, is sometimes
used as an alternative to peat in growing media.
COMPOST Strictly speaking, manure of organic origin
but more commonly used in the landscape industry
to refer to the growing medium.
COMPOUND LEAF A leaf made up of two or more leaflets
(q.v.) attached to the leaf stalk.
CONCENTRATE A formulation containing the active
ingredient at a higher concentration than is normally
used, hence requiring dilution before use.
CONDUCTIVITY A measure of the level of soluble
salts in a growing medium.
CONIFER Popular name for cone-bearing trees belonging
to the order Coniferales. Includes firs, cypresses,
pines and spruces.
CORDATE Heart-shaped; similar to ovate (q.v.)
but with more pronounced basal lobes.
CORIACEOUS Having a stiff or leathery texture
e.g. as in the leaves of Sansevieria trifasciata.
COROLLA Collective term for the petals of a flower
that may be separate or fused.
CORTEX The layer of tissue immediately below the
COSHH Control of Substances Hazardous to Health
COTYLEDON The first leaf or leaves in a germinating
CRENATE Leaf margin with shallow, rounded teeth.
CRISTATE With a crest-like growth in one area
of the leaves, stems or flowers.
CROWN The basal part of a herbaceous perennial
from which roots and stems grow.
CULTIVAR Short for “cultivated variety”
and referring to a plant variety that has originated
in cultivation, rather than in the wild.
CUNEATE Wedge-shaped; usually refers to leaves
which taper from a broad tip to a slender base.
CUTICLE The waxy covering on leaves and stems
that prevents excessive water loss.
CUTIN The complex material from which the cuticle
(q.v.) is made.
DAMPING OFF A disease of plants, especially seedlings,
encouraged by cold, wet soil and crowded conditions.
DECIDUOUS Describes plants that shed their leaves
before the winter or dormant period.
DENTATE Leaf margin with outward-pointing teeth.
DENTICULATE Finely-toothed version of dentate
DICHOTOMOUS STEM One which repeatedly forks into
two diverging branches.
DISTICHOUS Having leaves or flowers arranged in
two vertical rows on either side of the stem.
DIVISION Highest category or grouping in the plant
kingdom; sometimes called Phylum (q.v.). Also
describes a method of propagation that involves
splitting the root-ball into two or more sections.
EFFLORESCENCE The layer of crystalline salts sometimes
found on the surface of old compost.
EMULSION CONCENTRATE A solution of an active ingredient
in solvents together with emulsifiers that allows
it to be diluted with water to the concentration
required for use.
ENDEMIC A plant which grows naturally in a specific
area/country and nowhere else.
ENDODERMIS The innermost layer of cells in a plant.
ENTIRE Having a smooth, undivided edge.
ENTOMOPHOBIA Morbid fear of insects.
ENZYME A protein that acts as a catalyst in a
specific biochemical reaction.
EPIDERMIS The outermost layer of cells in a plant.
EPIPHYTE A plant without soil roots that is supported
on other plants or rocks e.g. orchids, bromeliads.
Also known as “air plants” they are
not parasitic but get nourishment from the rainwater
and debris that collects on their host.
EVERGREEN A plant that retains it foliage throughout
the year, shedding and replacing a few leaves
at a time.
EXOTIC A plant which is not native to the region.
F1 HYBRID The first generation offspring of two
FAMILY A group of similar genera (q.v.).
FASTIGIATE Of erect habit with a conical or tapering
outline e.g. the Lombardy Popular.
FIELD CAPACITY The volume of water held by a growing
medium after it has been saturated and allowed
FLORET One of the tiny flowers that make up a
larger, composite flower or inflorescence (q.v.).
FLOWER The reproductive part of seed-bearing plants.
FORM A term used to describe a sub-species, or
any plant that varies slightly from the norm e.g.
in flower colour or leaf shape.
FORMULATION The term given to describe the physical
nature of the formulated active ingredient, e.g.
wettable powder, gel, etc.
FROND Alternative name for the leaf of a fern
FUNGUS An organism without chlorophyll, which
feeds on organic matter. The cause of many infectious
GENUS A grouping of species with similar characteristics
e.g. Ficus, Dracaena. Collections of similar genera
are grouped into families (q.v.).
GLABROUS Smooth or hairless.
GLOCHID A short, barbed hair, many of which form
tufts on some species of cacti.
GROWING POINT The tip of a stem from which new
GUARD CELL One of the pair of crescent-shaped
cells that control the opening and closing of
the stomata (q.v.).
GYMNOSPERM A member of one of the seed-bearing
classes of plant.
HABIT The general or overall growth pattern of
a plant e.g. bushy, conical, erect.
HARDY Able to withstand prolonged exposure to
cold temperatures, including frosts.
HASTATE Triangular or spear-shaped.
HAZARD A possible source of danger.
HEARTWOOD The inner core of a woody plant which
has ceased to contain living tissue but provides
much of the mechanical support.
HERBACEOUS Without a woody stem.
HETEROPHYLLUS Bearing leaves of different shape
and/or function on the same plant e.g. Hedera
HETEROTROPHIC Describing an organism that feeds
on organic matter produced by other organisms.
Includes fungi and parasitic plants.
HONEYDEW The sweet, sticky secretion left on plants
by insects such as whitefly and aphids.
HSE Health and Safety Executive.
HUMUS Organic constituent of soil, formed by the
decomposition of plant and animal materials.
HYBRID Plant produced by cross-fertilising two
plants of the same family but different species,
variety or genera.
HYDROCULTURE The form of hydroponic (q.v.) cultivation
and maintenance used for interior landscaping.
HYDROPHOBIC Repelling or having an aversion to
HYDROPONICS A method of growing plants in water.
The roots are supported by a sterile medium such
as LECA (q.v.) or sand and nutrients are added
in a balanced liquid fertilizer.
HYGROMETER An instrument for measuring the humidity
of the air.
HYGROSCOPIC Absorbing or attracting moisture from
ILG Interior Landscape Group; section of BALI
INCIDENT An unforeseen occurrence which does not
lead to injury to persons or damage to property,
but which could do so in other circumstances.
INCISED Describing leaves with deeply cut or toothed
INFLORESCENCE A general term for the part of a
plant that bears the flowers.
INORGANIC Of mineral origin.
INTERNODE The section of stem between two nodes
LAMINA The main, usually flattened portion of
a leaf. Also known as the leaf blade (q.v.).
LANCEOLATE Shaped like the head of a lance.
LATERAL BUD A bud which arises on the side of
a main or leading stem.
LATEX Fluid exuded by some species of plant e.g.
the milky secretion in Ficus benjamina.
LEAFLET Any segment of a compound leaf (q.v.).
LECA Trade name for round pebbles of fired clay
used in hydroculture, as a drainage layer in the
base of plant containers or as a decorative soil
LENTICEL Any of the raised pores in the stems
of woody plants that allow gas exchange between
internal cells and the environment.
LETHAL DOSE 50 The measurement of toxicity of
a pesticide needed to kill 50% of laboratory test
animals when given either orally or dermally.
Usually expressed as milligrams of technical material
per kilogram of body weight (mg/kg).
LIGNIN An organic material that strengthens the
cell walls of many plants especially trees.
LIP The lowest segment of orchid and similar flowers;
it usually differs in colour or form from the
LOAM A soil consisting of fine clay, sand and
decayed organic matter.
LUX A unit of illumination or brightness, equivalent
to one lumen per square metre.
MERISTEM The extreme tip of a stem or root containing
actively dividing cells.
MESOPHYLL The inner tissue of a leaf.
METABOLISM All the chemical processes that produce
energy in a living organism.
MICRO-ENCAPSULATION The term given to the formulation
of an active ingredient that has had a “plastic”
coating added to it. This serves as a protective
layer to allow the slow release of the active
ingredient e.g. Osmocote granules.
MICRON One millionth of a metre.
MIDRIB The central vein (q.v.) of a leaf.
MITOSIS Cell division that results in two identical
MONA Trade name for a sub-irrigation system invented
MULCH A layer of organic material, such as bark
chippings or leaf mould, that is spread over the
growing medium for decoration or to retain moisture.
NECROTIC Describing dead plant tissue, which usually
becomes darker in colour. A common symptom of
NEUTRAL Refers to a material, e.g. soil, water
with a pH level of 7.0 i.e. neither acid nor alkaline.
NODE The point at which a leaf or bud joins the
stem and from which lateral shoots grow out.
OASIS Trade name for a light, porous material
used to support artificial and real cut flower
stems in small displays.
OBOVATE Reversed ovate (q.v.), with the point
at the stem end of the leaf.
OPPOSITE Refers to leaves borne in pairs, one
on either side of the stem.
ORDER A grouping of similar families (q.v.). Similar
orders are placed in classes (q.v.).
ORGANIC Of plant or animal origin.
OSMOSIS The passage of a solvent, such as water,
through a semi-permeable membrane, from a dilute
solution to a more concentrated one.
OVATE Egg-shaped; usually refers to the outline
of a leaf, which may be slightly pointed.
OVOID Another word for ovate (q.v.) but more commonly
applied to a whole object rather than just its
PALISADE LAYER The layer of elongated cells just
below the epidermis (q.v.).
PALMATE Describing a compound leaf that has the
appearance of an outspread hand.
PARASITE (From Greek – Para = Beside, Site
= Food) Organism which lives in or on another
organism and feeds on it, for at least part of
PATHOGEN A micro-organism that is capable of causing
PATHOGENIC Causing disease.
PEAT Partially decomposed sphagnum moss or sedge
extensively used in growing media.
PERENNIAL A plant that lives for many years.
PERICYCLE A layer of cells within the endodermis
and most prominent in roots.
PETIOLE The slender stalk joining leaf to stem.
pH A measure of the hydrogen ion (H+) concentration,
and hence of the acidity or alkalinity of an aqueous
PHLOEM Vascular tissue whose principal function
is the transport of sugars and other nutrients
around the plant.
PHOTOSYNTHESIS The process by which green plants
use the sun’s energy to convert carbon dioxide
and water into carbohydrates.
PHYLUM The animal equivalent of “division”
(q.v.) but now often used in its place.
PHYTOTOXIC Poisonous to plants.
PINCHING OUT Removing the growing points (q.v.)
of a plant to stimulate branching lower down the
PINNATE Describing a compound leaf with two rows
of leaflets (pinnae) on either side of the midrib
e.g. as in Nephrolepis exaltata.
PITH Plant tissue found in the centre of many
stems and roots.
PLUMULE The embryonic shoot in a germinating seed.
POT BOUND A plant growing in a pot which is too
small for further root expansion.
RADICLE The embryonic root in a germinating seed.
RELATIVE HUMIDITY The ratio of the actual to the
maximum possible amount of water vapour in the
air at a given temperature. Usually expressed
as % RH.
RESISTANCE The ability of an animal to withstand
the effects of a normally applied concentration
of a chemical and to pass this on genetically
to the next generation.
RESPIRATION The process by which plants break
down sugars, taking up oxygen and releasing carbon
RETICULATE Describing a leaf with a conspicuous
network of veins e.g. Hedera helix.
RHIZOME A horizontal stem, usually growing underground,
which produces roots and shoots and often acts
as a storage organ.
RHOMBOID Almost diamond-shaped.
RISK The likelihood or possibility of suffering
ROOT HAIRS Microscopic root projections responsible
for absorbing water from the soil.
ROOT CAP A hood-shaped layer of cells at the tip
of a root that protects it from abrasion as it
grows through the soil.
RUGOSE Having a wrinkled or corrugated appearance.
SAGITTATE Shaped like an arrowhead.
SAP The solution of mineral salts and sugar that
moves around a plant in the xylem and phloem vessels.
SAPWOOD The outer layer of wood which, in a growing
tree, contains living tissue and reserve food
SBS Sick Building Syndrome (q.v.).
SENSITISER An agent which causes an allergic reaction
when in contact with skin or other parts of the
SERRATE Leaf margin with forward pointing teeth,
rather like a saw.
SESSILE Stalkless leaves or flowers which emerge
directly from the stem.
SHRUB Woody plant with a framework of branches
but little or no central stem.
SICK BUILDING SYNDROME Symptoms such as headache,
lethargy and eye irritation which appear to be
more common amongst workers in so-called “sick”
buildings than in others.
SIMPLE LEAF A leaf that is not divided into separate
SOLUTION A liquid mixture of chemicals, e.g. solid
in liquid or liquid in liquid.
SOLVENT A liquid other than water, which is capable
of dissolving chemical substances.
SPADIX A fleshy flower spike with tiny florets
embedded in its surface. Most commonly found in
the Araceae family e.g. Spathiphyllum wallisii.
SPATHE The large, sometimes highly coloured bract
that surrounds or encloses the spadix (q.v.).
SPECIES A group of individual plants, subordinate
in classification to genus (q.v.), having members
which may breed together and differ only in minor
SPORE The tiny, single-celled reproductive body
produced by fungi, ferns and mosses. Equivalent
to the seeds found in most other plants.
STANDARD Popular term for a tree-like plant with
an unbranched main stem and compact head of foliage.
STOMATES (USA) Small pores, found predominantly
on the underside of leaves, which allow air and
moisture vapour to pass in and out of the plant
(singular = stoma – UK, stomate - USA).
STOPPING Another word for pinching out (q.v.).
SUCCULENT A plant with thick and fleshy leaves,
stems or roots capable of storing water.
SUSCEPTIBILITY The opposite of resistance. The
condition where an animal is unable to withstand
the normally applied concentration of a chemical.
SUSPENSION Insoluble particles uniformly distributed
in a fluid.
SYMBIOSIS An intimate relationship between two
or more different organisms, usually to their
mutual benefit e.g. the nitrogen-fixing bacteria
on tree roots.
SYSTEMIC A pesticide that is absorbed by a plant
and transported throughout its tissue.
TAPROOT The main descending root of a plant.
TENDER A plant that is liable to injury from cold.
Often applied to interior plants that require
minimum temperature of 15?C (59?F).
TENDRIL A thread-like growth, usually arising
from the leaf axil of a climbing plant, which
twines around the supporting structure. In some
cases the leaf stalks act as tendrils.
TERMINAL BUD The uppermost, usually central bud
on a plant.
TERRARIUM A partly or entirely closed glass container
used to house a collection of interior plants.
TESSELLATED Describing leaves and petals which
are chequered with spots or marks in contrasting
TOPIARY The art of clipping shrubs into ornamental
TOXICITY The capability of a chemical material
to injure or kill. Measured by the lethal dose
(LD%) needed to kill a specified percentage of
test animals (usually 50%).
TRACHEID One of the needle-like cells that conduct
water in softwood trees e.g. pine, spruce, and
TRANSLOCATION The conduction of soluble materials
from one part of a plant to another.
TRANSPIRATION The loss of water through a plant’s
TRANSPIRATION STREAM The flow of water from the
roots to the leaves.
TREE A woody perennial plant with a distinct stem
TYPE Specimen having the essential characteristics
of its plant grouping.
VARIEGATED Having leaves or flowers that are striped,
spotted or otherwise patterned in more than one
VARIETY A member of a plant species that differs
from the others in some inheritable way e.g. colour,
leaf shape. It should only be used for naturally
occurring plants, not those bred in cultivation,
which are called cultivars (q.v.).
VEGETATIVE Plant propagation by any method other
than seed germination e.g. layering, grafting.
VEIN A strand of conducting tissue typically found
in leaves. Large veins are sometimes called “ribs”
and the central vein, extending from the petiole
(q.v.) is called the midrib (q.v.).
VESSEL The tube-like duct which carries sap in
WATERLOGGED Saturated with water.
XEROPHYTE A plant that is adapted to living in
very dry conditions e.g. cacti, succulents.
XYLEM Woody vascular tissue used for transporting
water and dissolved minerals.