search
  1. Kansas Forest Service
  2. »About Us
  3. »Glossary of Terms

Kansas Forest Service

Kansas Forest Service
2610 Claflin Road
Manhattan, KS 66502
785.532.3300

Subscribe to our mailing list
* indicates required
* Email Address

First Name

Last Name

Glossary

Abiotic

Nonliving; also refers to plant problems caused by nonliving agents, such as drought, lawn mowers, string trimmers, and so forth.

Abscisic Acid

A growth-regulating chemical found in plants that cause the stomata to close during drought stress. Active Ingredient: (AI) The chemical in a pesticide formulation primarily responsible for phytotoxicity to its target and which is identified as the active ingredient on the product label.

Adventitious

A plant part that appears in an area where it normally would not, such as adventitious roots or shoots emerging from stems.

Allelochemicals

Chemical substances produced by plants that protect them from their natural enemies and environmental stress. Examples of allelochemicals include tannins and other phenolic compounds (such as tannin acid), terpenes (such as pine resins and fragrant chemicals in herbs and spices), and alkaloids (such as nicotine and morphine).

ANSI A300

The American National Standards Institute standard for pruning trees and shrubs in landscapes.

ANSI Z60.1

The American National Standards Institute standard for nursery stock.

ANSI Z133.1

The American National Standards Institute standard for safe working practices in and near trees.

Apical Dominance

A growth pattern in which a plant maintains a strong central stem, or leader, due to inhibition of lateral buds by a chemical signal from the terminal buds.

Arboriculture

The science and art of caring for trees, shrubs and other woody plants in landscape settings.

Arborist

A person possessing the technical competence through experience and related training to provide for or supervise the management of trees or other woody plants in a landscape setting.

Auxin

A growth-regulating chemical that can inhibit lateral bud development but that can also stimulate cell enlargement and initiation of roots in other parts of the plant.

Balled-and-Burlapped

A term that describes trees and shrubs harvested with the root system enclosed in a soil ball that is held together with burlap and twine, a wire basket, or both.

Bark

Nontechnical term applied to all tissues outside the vascular cambium in a woody stem.

Bare-Root

Trees and shrubs harvested with an exposed root system and with no soil covering their roots.

Basal Flare

The transitional are from a tree's stem to its root system. Normally the stem flares out to a larger diameter as it approaches the root area.

Biomass

The total mass, at a given time, of living organisms of one or more species per unit area (species biomass) or of all the species in the community (community biomass).

Biotic

Alive; caused by living agents. Usually a reference to a disease caused by living microorganisms.

Branch Bark Ridge

A more or less commonly occurring raised area of bark tissue in the union of two branches or two stems or in the union of branch and stem.

Branch Collar

A swelling at the base of a branch where it joins the trunk or larger branch resulting from overlapping trunk and branch tissue.

Branch Protection Zone

A thin zone of starch-rich tissue at the base of a branch where chemicals are deposited to retard the spread of discoloration and decay.

Branch Stub

The part of the branch beyond the collar inadvertently left following branch removal.

Branch Union

The place where two branches or stems join or where a branch meets a trunk.

Border tree

A tree jointly owned by adjacent property owners due to its location on the property line.

Bracing

Installation of steel rods or bolts through the stems or limbs to reducing twisting or splitting of the wood.

Bulk Density

A measurement of the mass of soil per unit volume, usually grams per cubic centimeter.

Cabling

Installation of steel cables, attached to lag screw or bolts placed in tree limbs, to provide additional support or to limit movement and stress of limbs.

Caliper

Trunk diameter measured 6 inches from the ground; if caliper is greater than 4 inches, the measurement is taken 12 inches from the ground.

Callus

A term synonymous with wound wood.

Callus Tissue

Tissue formed when the plant is wounded by pruning, insects, and other sources of mechanical injury. Callus tissue grows over the wound, isolating it from undamaged tissue and the external environment. Also known as wound periderm tissue.

Cambium

The tin layer of cells in the inner bark that gives rise to the conductive tissues, xylem, and phloem.

Candle Stage

The period of time after budbreak when shoot elongation normally occurs in conifers.

Canker

A depression or opening in the bark usually caused by a fungus or bacterium.

Carbohydrates

Materials (sugar and starch) produced by plants during photosynthesis that serve as an energy source.

Causal Stage

Either a biotic or an abiotic agent that causes a disruption of a plant's normal growth or physical properties.

Cavity

An open and exposed area of wood, where the bark is missing and internal wood has been decayed and dissolved.

Central Leader

A dominated stem located more or less in the center of the canopy.

Certified Arborist

An arborist who has passed an exam and received, on a regular basis, continuing education administered by the International Society of Arboriculture (Champaign, IL).

Chlorophyll

The name given to the green pigment in the plant cells that is responsible for absorbing light energy during photosynthesis.

Clean (cleaning)

Removes dead, broken, rubbing, or diseased branches and foreign objects; could also include removing or subordinating weakly-attached branches.

Codominant Stem

A stem growing at about the same rate, and with nearly the same diameter, as another stem originating from the same union; often the piths are connected in the union.

Compaction

The compression of soil, causing a reduction of pore space and an increase in the density of the soil.  Tree roots cannot grow in compacted soil.

Compartmentalization

Physiological process that creates the chemical and physical boundaries that limit the spread of disease and decay organisms. Compost: Mixture that consists largely of decayed organic matter used for fertilizing and conditioning soil.

Conifer

Plant that bears seeds in a cone.

Conk

The large sporte-bearing structures of wood-decay fungi.

Containerized

Plant material grown in a nursery and placed in a container before shipment.

Core Sample

A sample of wood extracted from a trunk or branch, using an increment borer tool. The resulting core can be analyzed for characteristics of growth, structure, and decay, and for species identification.

Critical Root Zone

Portion of the root system that is the minimum necessary to maintain vitality or stability of the tree.  Encroachment or damage to the critical root zone will put the tree at risk of failure.

Crown Cleaning

The removal of dead, dying, diseased, crowded, weakly attached, and low-vigor branches and watersprouts from a tree crown.

Crown Thinning

Includes the practice of crown cleaning and the selective removal of branches to increase light penetration and air movement in the crown.

Crown Raising

The removal of the lower branches of a tree in order to provide clearance for buildings, pedestrians, vehicles and vistas.

Crown Reduction

Pruning practice which is used to reduce the height and/or spread of a tree.

Crown Restoration

Pruning to improve the structure and appearance of a tree that has been topped, severely pruned, or damaged by storms.  Restoration pruning typically requires several prunings over a number of years to redevelop a strong branching structure.

Cultivar

A cultivated variety of a species typically propagated by cuttings, tissue culture, grafting, or budding. Decay Progressive deterioration of organic tissues, usually caused by fungal or bacterial organisms, resulting in loss of cell structure, strength, and function.  In wood, the loss of structural strength.

Deciduous

Perennial plant that loses all its leaves at one time during the year.

Decurrent

Round-headed tree form; no leader to the top of the canopy in an open landscape without pruning.

Defoliation

Loss of leaves.

Diagnosis

The process of determining the cause of a disorder.

Diameter at Breast Height (DBH)

Stem diameter measured at a point 4.5 feet above the ground.

Disease

Any disturbance of a plant over some period of time that interferes with its normal structure, function, or economic value and that induces symptoms.

Disorder

Any disease caused by a noninfectious (non-living) agent.

Dominant Leader/Trunk

The one stem that grows much larger than all other stems and branches; at least 1/3 bigger than the lateral branches located nearby.

Dormancy

In plants, period of inactivity during winter or periods of cold.

Dormant

Seasonal quiescent state in which the plant suspends growth.  Usually occurs during winter months.

Double Leader

Two co-dominant stems originating more or less in the center of a tree and jointly assuming the role of the leader.

Drop Cut

Making three cuts, beginning with an undercut, to remove a branch to prevent bark tearing.

Encircling Roots

Roots that grow in a circular manner rather than radiating out from a plant's root collar area.

Epicormic Sprout

A shoot that arises from latent or adventitious buds - also known as watersprouts - that occurs on stems and branches and on suckers produced from the base of trees. IN many plants, a symptom of stress; in a few species, a natural trait.

Espalier

A plant trained to grow flat against a support (such as a wall).

Evergreen

Plant that retains its leaves for more than one growing season.

Excurrent

Conically shaped tree form with a dominant leader or trunk extending to the top of the tree.

Feature Trees

Trees located by themselves with few other trees nearby surrounded by turf, ground cover, or shrubs.

Fertilization

The process of adding nutrients to a tree or plant; usually done by incorporating the nutrients into the soil, but sometimes by foliar application or injection directly into living tissue.

Foliage

The live leaves or needles of the tree; the plant part primarily responsible for photosynthesis.

Frost Crack

Longitudinal cracks in the stems of trees and shrubs that run parallel to the wood grain and extend to the center of stems and branches. Usually associated with extremely cold temperatures and previous wounds.

Fruiting Structure, or Fruiting Body

A fungal structure made of mycelium and containing spores.

Fungicide

A chemical compound that is toxic to fungi.

Gall

An abnormal swelling or growth of plant tissue that is initiated by a pathogen, insect, or mite.

Girdling Root

A plant root that encircles the plant rather than spreads out radially from the plant.

Glazing

To give a smooth, glossy surface to a substrate. Soils can become glazed and somewhat imperious to water and roots.

Graft (or bud) Union

The point where the cut surfaces of two plants join to form a living union.

Grafting

Method of plant propagation by attaching a bud or a scion of one plant, forming a living union.

Growth Increment

The incremental growth added as new wood each growing season over existing wood. This is seen as growth rings in cross-sections of wood.

Growth Ring

A new layer of xylem produced by the secondary growth system (cambium) typically demarcated by a visible change in color. Hardiness Ability of a plant to survive low temperatures.

Hardwood

Trees that lose their leaves in autumn; also refers to the wood produced by these trees.  Hardwoods are the predominant type of tree in the deciduous forest.

Hazardous Condition

A condition in a tree that could result in injury to people or damage to property.

Heading

A pruning cut in which the cut removes a branch to a stub, a bud, or a lateral branch not large enough to assume the terminal role.

Heading Cut

A type of pruning cut that prunes a shoot no more than 2 years old back to a bud; cutting an older stem back to a lateral branch less than 1/32 the diameter of the cut stem; cutting a stem to an indiscrimate length.

Heartwood

Xylem in the center of a trunk or branch that receives deposits from other portions of the tree; wood lacking living cells.

Herbicide

A chemical that kills plants or inhibits their growth; intended for weed control.

Horticulture

Cultivation of fruits, vegetables and ornamental plants. Included bark Bark pinched or embedded between two stems or between a branch and trunk preventing formation of a branch bark ridge; an indication of a weak union; a crack in the union.

Insecticide

A chemical that kills insects.

Integrated Pest Management

System of controlling pests and their damaging effects through mechanical, chemical, biological, cultural and regulatory techniques. Landscape Areas of land that are distinguished by differences in landforms, vegetation, land use, and aesthetic characteristics.

Latent Bud

A suppressed bud lying just beneath bark, capable of forming a shoot, that grows enough each year to stay even with the bark.

Lateral Branch

A stem arising from a larger stem.

Leader

A stem that dominates a portion of the canopy by suppressing lateral branches.

Liners

Young seedlings planted in a container or field nursery for growing on to a landscape sized trees.

Lion's Tailing

The improper practice of pruning out the inside lateral branches of a tree.  Lion's tailing, by removing most of the inner foliage, displaces the weight to the ends of the branches and may result in weakened branch structure, limb breakage, sunburned branches, and watersprouts.

Live Crown Ratio

The ratio of the top portion of the tree baring live foliage to the cleared lower portion that includes the trunk, without live foliage.

Macronutrient

An essential element required by plants in relatively large quantities.

Mature Trees

Trees that have reached at least 75 percent of their final height and spread.

Microclimate

Environmental conditions of a specific limited area.

Micronutrient

An essential element required by plants in relatively small quantities.

Mitigation

Action taken to alleviate potential adverse effects on wetlands and fish habitat undergoing modification.  Also commonly used to mean compensation for damage done.

Mulch

Any material such as wood chips, straw, sawdust, leaves, and stone that is spread on the surface of the soil to protect the soil and plant roots from the effects of raindrops, soil crusting, freezing, and evaporation.

Mycorhizae

Fungal organisms that form beneficial associations with plant roots, increasing the effective surface area of the roots for absorption of water and nutrients from the soil.

Natural Tree Form

The form that develops in the trees native habitat without disturbance from human activities.

Natural Pruning

The natural death of branches on the stem of a tree from such causes as decay, or deficiency of light or water, or snow, ice and wind breakage.

Natural target pruning

Pruning technique in which only branch tissue is removed, with the cut placed just beyond the branch collar.

Nutrients

The substances, such as mineral elements and compounds, including water and air, that a plant synthesizes into the complex compounds of tissue.

Node

The point on a stem where a leaf and bud emerge. Branches emerge from nodes.

Overmature

Tree or stand that has passed the age of maturity where the rate of growth has diminished and the trees are weakened.

Over-mature Trees

Trees that have reached their final height and spread that are declining in vigor.

pH

A logarithmic measure of acidity or alkalinity. A pH level of 7 is neutral. A pH level of 1 through 6 is acidic, and 8 through 14 is alkaline.

Phloem

Living cells located just outside the cambium that moves sugars and other components about the plant.

Photosynthate

A product that results from photosynthesis; a source of chemically stored energy.

Photosynthesis

The process that turns light energy into chemical energy in green plants.

Pith

The center, typically soft portion of a branch or stem that forms the first year that lacks living tissue.

Plant Growth Regulator

A substance used for controlling or modifying plant growth processes without severe phytotoxicity.

Pollarding

The specialized training technique used to maintain a tree at a specified height with regular heading to the exact same position; not the same as topping.

Pollarding Cut

A pruning cut that removes sprouts back to the same location annually or every other year.

Postemergence

Refers to pesticides or herbicides applied after emergence of the specified crop or weed.

Preemergence

Refers to pesticides or herbicides applied before emergence of the specified crop or weed.

Pruning

Selective removal of woody plant parts of any size, using saws, pruners, clippers, or other pruning tools.

Pruning Cycle

The interval or time between each pruning.

Radical Crack

A crack beginning from a ring crack that forms along a ray and may extend to the bark.

Rays

Long groups or plates of living cells that extend from the phloem into the xylem toward the center of the trunk.

Reduction Cut (Drop-Crotch Cut)

Reduces the length of a branch or stem back to a live lateral branch large enough to assume the apical dominance - this is typically at least one-third the diameter of the cut stem.

Renovate

Cutting a shrub back to the ground or nearly so in order to increase vigor.

Resistograph

A gear-driven drilling instrument which inserts a three-millimeter-diameter probe into a tree, and graphically or digitally records resistance to the probe; used to detect decay and defects.

Respiration

The series of reactions, occurring in the mitochondria, by which sugar is broken down to provide energy for plant functions. Oxygen is consumed and carbon dioxide released during respiration.

Restore (Restoring, Restoration)

The process of improving the structure of a tree that was previously topped, damaged, vandalized, or overthinned.

Ring Crack

A crack that forms along a wall 4.

Root Problems (Defects)

Conditions in the root system that could lead to poor health, or plants falling over such as circling roots, cut roots, decayed roots, no trunk flare, and deep planting.

Root Pruning

removes circling and girdling roots around trunk base; a technique of cutting many roots on a tree growing in a field nursery or landscape to prepare it for digging; cutting roots regularly to help keep a plant small.

Root System

The portion of the tree containing the root organs, including buttress roots, transport roots, and fine absorbing roots; all underground parts of the tree.

Root Zone

The area and volume of soil around the tree in which roots are normally found.  May extend to three or more times the branch spread of the tree, or several times the height of the tree.

Rounding over (Roundover)

Reducing the size of a tree by pruning the outer edge of a canopy with small-diameter (typically less than 2 inches) heading cuts; diameter of the cuts are typically small compared to a tree that was topped. Sapling A young tree about 1 to 3 years old.

Scion

A cutting of a twig or shoot that is grafted onto another twig or shoot.

Scorch

"Burning" of leaf margins caused by infection or unfavorable environmental conditions.

Senescence

The process of aging, decline, and death.

Slime Flux

A liquid composed of bacteria and their byproducts, that ooze out of wounds in trees.

Softwood

Cone-bearing trees with needles or scale-like leaves, also refers to the wood produced by these trees. Softwoods are the predominant type of tree in coniferous forests.

Soil

A dynamic natural body composed of mineral and organic materials and living forms in which plants grow.

Soil Amendment:

Material added to soil to alter its physical or chemical properties.

Soil Compaction

The reduction of the total pore space in a soil, especially the macropores.

Species

The main category of taxonomic classification into which living organisms are subdivided, comprising a group of similar individuals having a number of correlated characteristics.

Standards

Industry accepted definitions and principles.

Starch

A chain of sugars linked together that stores chemical energy for later use by the plant.

Stress

Unfavorable deviation from normal. The action on a body of any system of balanced forces whereby strain or deformation results.  In arboriculture, the adverse alteration of tree health by abiotic or biotic factors.

Structural Pruning

Pruning that influences the orientation, spacing, growth rate, strength of attachment, and ultimate size of branches and stems resulting in a strong tree.

Structure

The spacing, orientation, and size of branches relative to the trunk; the arrangement of trunk and branches; the tree's architecture.

Subordination

(Subordination Pruning, Suppression) Removing the terminal, typically upright or end portion of a parent branch or stem to slow growth rate so other portions of the tree grow faster.

Sunscald

The term applied to dead or injured bark and cambial tissues. Sunscald results from cold bark temperatures followed by warm bark temperatures. This condition usually occurs when thin bark tissues are warmed well above air temperatures in the winter months due to bright, sunny exposures. When temperatures suddenly drop from passing clouds or the onset of evening, freezing injury to the warmed tissues occurs. Also called frost cankers.

Taper

The thickening of a stem or branch toward its base.

Target

Any person or object within reach of a falling tree or part of a tree, that may be injured or damaged.

Thinning

Pruning technique in which branches are removed at their point of origin.

Topping

An inappropriate technique to reduce tree size that makes heading cuts through a stem more than 2 years old; a type of pruning cut that destroys tree architecture and serves to initiate discoloration and perhaps decay in the cut stem.

Translocation

Transfer of nutrients (or virus or herbicide) through a plant.

Transpiration

Evaporation of water vapor from foliage.

Tree Habit

The form or shape taken on by the canopy.

Tree Protection Zone

A designated area around trees where maximum protection and preservation efforts are implemented to minimize soil compaction, etc.

Tree Spikes

Devices that are attached to boots and used by tree workers to aid in tree climbing. Their use inflicts tree wounds.

Urban Forestry

Management of naturally occurring and planted trees in urban areas.

Utility Arborist

An arborist with specialized training who prunes trees near energized wires and other utility equipment.

Vigor

Overall health; the capacity to grow and resist physiological stress.

Visual Tree Assessment

Method of evaluating structural defects and stability in trees.

Wall 1

A term used to describe the boundary formed by plugging of xylem vessels, sometimes in response to injury; the weakest boundary that resists movement of discoloration and decay up and down the xylem.

Wall 2

A term used to describe the boundary between one growth ring and the next; a boundary that resists movement of discoloration and decay in toward the pith usually considered stronger than wall 1.

Wall 3

A term used to describe the boundary formed by rays; a boundary that resists movement of discoloration and decay around the trunk along growth rings usually considered stronger than wall 2.

Wall 4

A term used to describe the boundary formed by a reaction zone along the cambium in response to injury; the strongest boundary that resists movement of discoloration and decay into wood formed after injury.

Water Sprouts

Stems arising from interior branches often growing upright and vigorously, often as a result of a stress such as over pruning, drought, or root damage.

Weak Crotch

(Union) A union with included bark; a union that is relatively weak compared to other unions.

Winter Kill

Plants injured by cold winter temperatures or from becoming deadclimitized on warm days followed by cold nights.

Witches' Broom

Proliferation of many shoots near the end of a branch in response to the death of the terminal bud.

Woody

Plant type that contains secondary xylem.

Wound Closure

The process of forming callus and woundwood over a wound such as a pruning cut.

Woundwood

Differentiated woody tissue forming around a wound; such as a pruning cut. See callus for comparison.

Xylem

The woody part of the tree that begins on the inside of the cambium.