Portland Landscape Design and Arborist Tree Service

Arboriculture | Pruning Glossary

One of several topics from the M. D. Vaden Advice Index

Edited by Mario Vaden - 2009

Image: Hyperion in January of 2008 - see largest coast redwoods

Aeration: Making holes or sending air into root zones.

old growth Sitka Spruce forest log

ANSI A300: American National Standards Institute - standards tree care practices.

ANSI Z133.1: American National Standards Institute; standards of safety for tree care.

Antitranspirant: Chemical applied to reduce water loss through leaves and stems.

Anvil pruner: Tool with a blade that presses onto a flat surface - inferior to bypass pruner.

Arboriculture: Science of tree development and care.

Backfill: Soil and amendments to refill a hole around roots / in a trench.

Balled and burlapped: Trees grown and wrapped in burlap with twine or wire - B&B.

Bare root: Plants shipped without ball of soil, may be in moist compost.

Bark: Outer layer of branches, twig and trunks; the protective outer layer.

Branch: A stem that is attached to another larger stem, leader or trunk.

Branch bark ridge: Protruding bark above the union (crotch) of two branches or leaders.

Branch collar: An overlap of tissue of branch and branch, or branch and trunk, often appearing as a small bulge or collar giving a ringed appearance.

Bud: Small dormant apical or lateral meristem tissue which can “break forth” from a leaf axil, twig tip, apex of the tree, or from beneath the bark, and develop into a flower, twig or leaves.

Buttress root – large root that flares from the trunk near ground level.

Bypass pruner: Pruner with curved cutting blade and hook which slide past each other.

Cambium: Layer of meristematic cells, not far under the bark; producing the phloem layer which is closer to the bark, and the xylem tissue which is toward the inside; xylem basically being called” wood”.

Canopy: The branches and leaves altogether - the top of the tree. (the crown)

Carbohydrate: “Energy” food like sugars, starches, produced by photosynthesis.

Cavity: Opening or hollow in trunks or limbs of a tree - might be from decay or damage.

Central leader: Main central stem of a tree - “central” often implies the presence of one leader rather than several existing. A leader that’s outstanding amongst several leaders may be called the central leader, but all leaders together mean a tree is a multiple-leader tree.

Certified arborist: Professional tree service person certified with International Society of Arboriculture. Experience and tests and continuing education involved.

Co-dominant stems or trunks: Two equally competing terminal branches or leaders.

Compaction: Compression of soil that causes loss of pore space and causes soil to be more impenetrable, and less permeable.

Crotch: Top of the union or merging of two branches, or branch and trunk, or two leaders.

Crown: Portion of the tree above ground comprised of all the branches and foliage.

Crown cleaning: Removal of water sprouts, dead growth, dying growth, diseased tissue, broken limbs and structurally bad growth. Suckers are from ground level.

Crown reduction: It’s not topping. It is a reduction of the canopy incorporating proper pruning cuts and acceptable foliage removal.

Decay: Deterioration of wood tissue by fungus and bacteria.

Deciduous: Plants or trees that drop leaves, needles or foliage in winter.

Desiccation: Drying-out, or dried-out.

Dieback: When ends of twig or branches defoliate, decline and die back to remaining live plant parts. A totally dead tree has no dieback.

Dormant: A state of “rest” or halt in growth - trees almost always have something going on internally within either trunk or roots in the winter. The state of the tree that is dormant is fairly short. For example, after leaves fall, the roots continue to grow.

Drip line: The perimeter or boundary of the canopy at ground level. However far the branches extend to each side of the trunk, that’s how far out on the ground the drip line is - a circular area in general terminology.

Drop cut: The second handsaw, or chainsaw, cut in the process of a 3-cut branch removal procedure.

Drop zone – The general area where branches are dropped to or lowered to with rope, during tree pruning or removal. Evergreen: Trees that retain leaves or needles all year. Not the same term as “conifer” ( A larch is a conifer, but is deciduous and looses needles in the cold season).

Extension pruner: A hook and blade bypass pruner on a telescoping, fixed, or snap-together sections handle, operated by pulling a rope to close the cutting parts. May or may not have a saw blade attached. Fail: When a tree, trunk or branch breaks or falls. It did not succeed - hence “fail”.

Flush cut: An improper pruning cut that removes the branch collar and damages trunks or leaders. Flush cutting is not a “technique” but lack of it.

Girdling root: A root growing around part of the trunk or all of it that is restricting its expansion or outward growth.

Guying: Securing, repositioning or stabilizing of a tree with ropes, wires or cables attached to stakes or anchoring devices embedded in the ground or customized anchoring.

Hand pruners: A small tool designed for one-handed pruning cuts of small twigs and branches.

Hardened off: Gradually and successfully adjusted or acclimatized to a new environment whether it is a change in light, heat, cold or moisture.

Hardiness: The potential and inherent ability to withstand temperature extremes, temperature levels - this is climate and weather condition related.

Hardiness zone: Sections of a country, states or regions designated or assigned a number or letter or both, indicating the high and low temperatures as known from years in the past.

Heading back: Pruning shoots or twigs by 1/4 to 1/2 or so.

Heartwood: The inner wood of a trunk.

Horizon: A layer of the soil profile - a horizontal layer - depth varies.

Included bark: The bark or tissue lodged in the crotch of two branches, two leaders, or branch and trunk, which is a weak attachment. It is at the same area a bark ridge would be, only a bark ridge “ridges-up” whereas included bark is enfolded like a crease.

Lateral: A side branch or twig extending from another one.

Lateral bud: Vegetative buds on sides of twigs or branches.

Lateral root: Roots extending outward off main or buttress roots.

Leader: A main terminal leader of the tree. There can be two or more in which case the tree is a multiple leader tree. In very loose vocabulary, these could be considered trunks, but since they emerge from the trunk, above ground level, the correct term is “leader” or “leaders”.

Lopper: A pruning tool with two handles which cuts with a scissor-like action. This is a “hand-tool” but takes two hands.

Mature height: The tallest anticipated height a tree is expected to reach. This can be a deceptive term. It could be considered the highest the average group of gardeners and tree experts “envision” a tree becoming.

Meristem: Plant tissue that can divide to form new cells. This can be apical meristem at the tip of a leader, the tip of roots, and in the cambium layer below the bark which divides to produce new wood and other tissues, providing added girth to the trunk or branches.

Multiple leaders: Co-dominant stems competing for the dominant growth extension of tree. The term “competing” can be misleading, because many multiple leaders function and grow almost equally as if in unison at nearly identical rates. If not thinned to just one “leader”, the group of them is nearly all needed after the tree matures to a degree.

Mycorrhizae: “Fungus root” is the meaning and this is a symbiotic relation of fungus on, or attached, to roots and the roots with the fungus. Each benefit. Healthy soil retains this, but compaction and pesticides can damage or prevent it.

Native: A species that historically occurred or naturalized in a geographic region as opposed to being introduced.

Node: The point of attachment of leaves and axillary buds (the area of stem between nodes is called an internode).

Permanent branch: A branch that is intended to, and probably should be, left in place for the permanent branch structure of a tree - basically a scaffold limb.

pH: The measure of acidity in soil or mulch. Even tissue can have a pH.

Phloem: The food transport tissue of the tree, just outside the cambium and below the bark - basically the trees “downward freeway” for nutrient transport.

Photosynthesis: The food producing process usually occurring in leaves that results in the use of carbon dioxide and the release of oxygen.

Pole pruner: Same as “extension pruner”. Pole saw – A saw on a pole. See “extension pruner” and “pole pruner” - basically the same. The poles may have the saw, the pruner or both, attached.

Pollarding: A pruning technique to restrict tree height. Basically pruning back to the same framework of limbs every year - a cutting of every shoot. Causes fist-like knobs that need to remain.

Pruning: Removal of weakness in a tree, or dead growth. Removal of living limbs to direct the growth of a tree. In short - with technique, removing twigs and branches.

Radial trenching: A technique for improving soil aeration or drainage in root zones the trenches radiate from trunk in a pattern resembling bicycle spokes. This prevents cross-cutting large roots.

Raising: Removal of lower, lowest, branches for headroom, clearance or improved air circulation in the environment of the tree.

Reduction: A branch removal pruning, with technique, to reduce the overall dimensions of a tree canopy.

Restoration: Pruning to bring a tree’s form, branch structure or health to an improved state.

Root ball: The remaining roots and soil around the base of a tree trunk after it is dug for transplanting, or after harvest in a tree farm.

Root flare: The base of the tree that “flares” outward at the trunk collar between the main trunk and buttress roots.

Root pruning: Cutting roots, for whatever planned profitable reason, to prepare for transplant, to protect concrete like sidewalks, to prepare to sink root barrier in the ground, to eliminate root grafts with other trees that could transfer disease in the soil area.

Scabbard: A sheath for a pruning saw or hand pruners. Scaffold limb (s): Permanently planned and retained, larger limbs of the tree.

Scion: A detached shoot or cutting with buds, used to insert in another plant or tree or on a root stock for propagation.

Soil analysis: The results of a chemical test that determines soil pH, and nutrient content including nitrogen, phosphorus and potassium, as well as other minerals.

Stomata: Plural of “stoma” - the minute openings in a leaf though which gases and moisture can pass. Most often on the underside of the leaf.

Stress: A condition of a tree (not good) that means it’s not in a state of premium or reasonable growth. This can be the result of factors from drought, too much light or shade or the presence of chemicals.

Subordinate: Pruning a branch or leader to reduce it’s domination in relation to nearby branches and leaders.

Sucker: A shoot originating from a root or lower trunk - sprouts and water sprouts are shoots from up above.

Sunscald or Sunburn: Damage to tissue from too much exposure to sun, or because exposure to sun was increased too rapidly, as when a tree is removed from the sunset side of another tree causing immediate change from full shade to full sun on the trunk of the remaining tree.

Taper: A decrease in the diameter of trunk and branches from the base toward the tip.

Terminal bud: The bud at the apex of a stem - main central leader tip, the bud there.

Tree: A woody plant 2” or greater in diameter measured at ground level.

Tree protection zone: The area of soil and roots around a tree, usually fenced or marked off in a construction or traffic zone for protection to the soil, roots and trunk. A minimum of 8 to 10 feet and 1’ per inch of diameter at breast height - DBH - is proper.

Thinning: A selective pruning or thinning of stems and branches to increase air, moisture, or light penetration to canopy or ground. This can reduce the load bearing weight of snow and ice in winter.

Topping: Non-selective, “crew-cut” or severe style cutting of, and across the top of the tree, usually leaving large cross-cut stubs. Loose term is “hat rack” or “hat racking”.

Transpiration: the exuding of water vapor from pores - stomata- in leaves aiding nutrient transport.

Transplant: Moving a tree or shrub from one location to another - not usually thought of as from nursery or tree farm to a landscape.

Transplant shock: The tree is having a “TOUGH TIME” after being moved from point A to point B - that’s about the best way to say it.

Tree wrap: Material wrapped around tree trunks or limbs to protect from sunburn or for protection during transportation. Trunk: The lowest base stem that supports the tree - the link between the roots below, and the canopy above.

Tunneling: Boring a hole - a tunnel to be specific - under root zones, or through root zones, as opposed to trenching across entire roots - this is to reduce root damage, and can leave the soil surface undisturbed in many cases. Turgid: Sufficient water pressure in tissues.

Undercut: An undercut is the first of 3 cuts in the multiple 3 cut system to remove a branch without tearing bark. The undercut, and top cut are both made a little way out from the branch collar and trunk.

Vertical mulching: A boring or drilling of soil in the root zone and filling with porous material or other soil to improve aeration and water penetration, as well as introduce mycorrhizae, nutrients or organic matter.

Water sprout: A vertical shoot from a branch, or upper trunk, that is usually fairly speedy growing compared to most other branches.

Weak crotch: When 2 or more branches or leaders meet at a union which is weak - in most cases a weak “V” shaped crotch or union. Often, the bark in-between has included bark, contributing to the weakness.

Wound dressing: A coating or paint originally made to coat pruning cuts or wounds, proven to cause acceleration of decay. Not recommended except in isolated specific cases for control of insect or disease on a few species of trees.

Xylem: Water and nutrient conducting tissue inside the cambium, and produced by the cambium. It is usually the greater portion of the inside of the trunk called, in general terms - “wood”.


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