Glossary of Terms


arboretum (ahr-buh-ree-tum)

1. a site where trees are grown for education and research

arboriculture (ahr-bur-ah-kuhl-cher)

1. the art and science of caring for individual trees

arborist (ahr-buh-rist)

1. one possessing the necessary skills to care for individual trees

abatement ~ see hazard abatement
abdomen ~ the third and rearmost region of insect body
abiotic disease ~ disease resulting from nonliving agents
abscissic acid~ plant hormone that triggers leaf and fruit drop
abscission ~ leaf and fruit drop
abscission zone ~ area where cellular breakdown leads to leaf and fruit drop
absorbing roots ~ fine, nonwoody roots that take up minerals and water
absorption ~ taking up
accelerated erosion ~ rapid type of erosion induced by human activities
acclimation ~ process by which plants adapt to a different environment
acorn ~ hard-shelled, one-seeded nut of an oak, characterized with a cup (cap)
accident reconstruction ~ process of establishing the dynamics of an accident
accuminate ~ having an apex the side of which is gradual concave and taper
act of God ~ violent act of nature without human interference
actual damages ~ amount of damages awarded for actual or real loss or injury
acute ~ disorder that develops in a short period of time; sudden onset
adaptability ~ genetic ability to adjust to different environments
adequate ~ sufficient to solve a task at a level of thoroughness warranted
adpressed ~ in close, tight proximity
adventitious ~ bud/sprout/root developing outside usual order of time or place
advocate ~ one who represents a client, or helps a client achieve a goal
aeration ~ air provision to the soil
aerial root ~ adventitious root that hangs down from a stem or branch
aerial rootlet ~ small, root-like organ, on the stem of some climbing vines
aerosol ~ suspension of colloidal particles in a gas
aesthetic ~ visually pleasing landscape characteristic
afforestation ~ forest establishment in a deforested area
aging ~ orderly changes over time of an organism (genetically designed)
aggregate fruit ~ fused fruit cluster, individual ovaries, but all from one flower
aggregation ~ process whereby soil particles are bound together
air-layering ~ procedure to induce root development above natural grade
air terminal ~ uppermost point of a lightning protection system
allelopathy ~ inhibitory effect of natural plant chemicals upon another plant
allocation ~ carbon distribution process
alluvial soil ~ soil that develops from waterborne sediment; usually quite fertile
alternate ~ one leaf per node, alternating direction each node
alternate host ~ unlike host species needed by a pest to complete life cycle
anatomy ~ study of plant structure and composition
angiosperm ~ flowering, vascular plant, with covered seeds (hardwood)
anion ~ negatively-charged ion; resulting from molecule dissociation
annual ~ plant (started from seed) completing its life cycle in one year
annual rings ~ see growth rings
ANSI ~ American National Standards Institute (tree care operations standards)
antagonism ~ plant growth interference directly by another plant
anterior ~ toward the front or head (of an insect)
anthocyanin red or purplish plant pigment
antigibberellin ~ plant growth regulator; opposite effects of gibberellin
anthracnose ~ plant disease (fungi) characterized by limited necrotic lesions
antibiotic ~ damaging to life (chemicals usually of microbial origin)
antibody ~ specific protein produced by an organism in response to an antigen
anvil pruner ~ tool that cuts branches against a flat surface (not recommended)
apex ~ see apical
apical ~ having to do with the tip
apical bud ~ see terminal bud
apical dominance ~ upward terminal growth at the expense of lateral growth
apoplast ~ network of vessels, fibers, cell walls and open spaces in wood
appraisal ~ placing a monetary value on a plant by competent authority
appropriate ~ fitting a particular set of facts, circumstances or assignment
arbitration ~ organized process for resolving disputes outside of a courtroom
arboretum ~ site where trees are grown for education and research
arboricultural consultant ~ see consulting arborist
arboriculture ~ art and science of caring for individual trees
arborist ~ one possessing the necessary skills to care for individual trees
architecture ~ overall design (for a tree; tree crown shape)
ASCA ~ American Society of Consulting Arborists
asexual ~ vegetative; without sexual organs
asexual reproduction ~ propagation other than from seed; grafting, air-layering
assimilation ~ taking-up of elements & transforming them into plant tissue
assumption ~ fact/information not actually known, but believed to be true
attenuation ~ light intensity reduction through a canopy
autopsy ~ examination to determine death; possibly other than natural causes
auxin ~ plant growth regulator that governs cell elongation
avirulent ~ see nonpathogenic
axillary bud ~ leaf axil bud
back cut ~ cut made on the backside of a face cut, used to fell a tree
backfill ~ soil/amendments placed/replaced into the planting hole near roots
bacteria ~ plural of bacterium
bacterial wetwood ~sapwood/heartwood disease caused by anaerobic bacteria
bacterium ~ single-celled microorganism lacking chlorophyll and mitochondria
balled and burlapped ~ tree rootball wrapped in burlap for moving
barber-chairing ~ tendency of a tree or branch to pivot on a notch while felling
bareroot planting ~ installation of plants with naked/exposed roots
bark ~ protective covering of woody plants
bark crack ~ see growth crack
bark scribing ~ skillfully cutting away torn bark; leaving a smooth edge
bark tracing ~ see bark scribing
barrier zone ~ wall that separates inner infected wood from healthy wood
basal ~ see stem
basal flare ~ see root flare
basin ~ drained area where margins dip towards a common center
B&B ~ balled and burlapped
bell cap ~ cover device placed on an exposed, upright drainage tile
beneficial pruning ~ natural target pruning; only necessary plant parts removed
beneficial root pruning ~ beneficial pruning of roots (often during construction)
berm ~ ditch shoulder
berry ~ fleshy fruit containing more than one seed
biennial ~ plant (started from seed) completing its life cycle in 2 seasons
biodegradable ~ capable of decay by microorganisms
biological control ~ pest control method using natural predators or antagonists
biology ~ the science of living things
biomass ~ total dry organic matter at a given time of living organisms
biosphere ~ portion of the air, land and sea where living organisms exist
biotic disease ~ disease resulting from living agents
biotic potential ~ unrestricted growth rate of a species under ideal conditions
bipinnate leaf ~ double-pinnate
bird’s eye ~ small burl-like structures (dimples) that occur in some hardwoods
bisexual ~ functional male and female reproductive organs on the same plant
blade ~ broad, flat part of a leaf
bleeding ~ see gummosis
blight ~ sudden, severe wilting/death; disease that kills young growing tissues
blister ~ pest-induced leaf bubble
blowdown ~ see windthrow
blue stain ~ imparted by blue stain fungi, spread by boring beetles (conifers)
BOD ~ biological oxygen demand; amount of oxygen required to decompose
bog ~ wet, poorly drained, highly acidic, peat-accumulating wetland
bole ~ see stem
bone-faced wound ~ bright, case-hardened wound, with limited internal decay
bonsai ~ highly-developed pruning method of keeping a potted tree small
borer ~ see wood borer
boundary ~ border that defines an area
boundary line tree ~ tree owned in common by 2 adjoining landowners
bow ~ gradual downward branch curve
bracing ~ artificially supporting a weakened tree part with metal rods/screws
branch ~ extension of a tree’s stem, smaller than a stem, larger than a twig
branch angle ~ branch attachment angle
branch attachment ~ structural connection between branch & branch or stem
branch bark ridge ~ ridge created when adjoining branches push bark outwards
branch collar ~ swelling or shoulder area of a branch attachment
branch spacing ~ relative distance between branches (effects union strength)
brash wood ~ type of reaction wood that is weaker than normal wood
broadcast ~ scattered evenly across the surface
broadleaf ~ deciduous or evergreen tree with flat, broad foliage
brood tree ~ tree harboring breeding insects
brownfield ~ site of previous industrial activity, with disturbed/tainted soil
brown rot ~ brown, often crumbly, advanced wood decay (cellulose is digested)
brush ~ shrubby vegetation
bud ~ dormant shoot structure
budding ~ specialized grafting where a single bud is used (vs. a whole branch)
bud pruning ~ lateral bud removal, to prevent branch development
buffering capacity ~ soil ability to maintain pH
buffer zone ~ vegetative land strip used to enhance/protect natural resources
builder ~ one who acquires improved lots and oversees construction
bulk density ~ weight-per-unit-volume of a material
burl ~ see gall
burning ~ excessive commercial fertilizer root damage (may reverse sap flow)
bush ~ see shrub
butt ~ lower stem and upper buttress root area of a tree
buttress roots~ 3 to 11 large structural roots that spread laterally from the butt
buttress wood ~ see tension wood
butt rot ~ advanced butt decay
bypass pruner ~ proper tool that cuts branches by pushing past a flat surface
cabling ~ artificially supporting a weakened tree part with cables
caliper ~ see diameter
callus ~ undifferentiated tissue that forms at wound margins
cambium ~ meristematic cell layer that develops phloem and xylem
canker ~ localized, often sunken, necrotic lesion, with well-defined margins
canker face ~ outer surface of a canker (usually within margins)
canopy ~ expanded leafy top of a plant
capsule ~ dry, thin-walled fruit, that splits partly open at maturity
carbohydrate ~ organic carbon/water product of photosynthesis
carrying capacity ~ habitat capacity to sustain animal population indefinitely
carotenoid ~ yellow, orange or red plant pigment
case plan ~ organized analysis of a project; a budget of time and effort
caterpillar ~ butterfly or moth larva
cation ~ positively-charged ion; resulting from molecule dissociation
cation exchange capacity ~ soil ability to absorb and hold cations
catkin ~ compact, often drooping cluster of reduced, stalkless flowers
causal agent ~ biotic or abiotic agent capable of causing disease
caveat emptor ~ (latin) let the buyer beware
cavity ~ open tree hollow
CEC ~ cation exchange capacity
cell ~ basic structural building block of an organism
cellulose ~ world’s most abundant organic compound; made up of glucose units
central leader ~ see stem
chain of custody ~ control of evidence during dispute/resolution process
chambered pith ~ twig pith that’s divided crosswise by plates or membranes
channelization ~ converting a natural stream into a ditch for flood control
character ~ distinctive feature exhibited by all individuals
check ~ radial separation starting from the outside (normal drying of cut wood)
chelate ~ chemical compound that controls mineral solubility
chemotropism ~ plant growth towards a chemical stimulus
chernozem ~ type of black, fertile soil developed under a mixed-grass prairie
chlorophyll ~ complex green pigment found in chloroplasts
chloroplast ~ plant cell photosynthesis site
chlorosis ~ abnormal foliage yellowing
chronic ~ disorder occurring over a long period
civil engineer ~ one who designs grading, drainage and utility plans
class ~ taxonomic group between division and order
clay ~ very fine soil, with mineral particles less than .00008 inch in size
claypan ~ compact clay subsoil
clearcut ~ complete removal of all forest trees in one operation
clearing ~ open forest or woodland space
climate ~ long-term weather manifestation
climax community ~ stable, terminal stage of an ecological succession
clinometer ~ instrument used for measuring the height of trees
clone ~ genetically-identical, asexually-produced organism
closure ~ see wound closure
cluster effect ~ naturally-occurring groups of trees of similar characteristics
CODIT ~ compartmentalization of decay in trees (4 model walls)
codominant branches ~ two adjoining, near equal-size branches
codominant stems ~ two adjoining, near equal-sized stems
codominant tree ~ when a tree’s crown helps form the upper canopy
cold hardening ~ increasing plant cold resistance
cold hardiness ~ subfreezing temperature tolerance
collar crack ~ butt crack originating in buttress roots (associated with rot)
colloidal ~ matter of very fine particle size
community ~ assemblage of plants and animals living in a given area
compaction ~ total soil porespace reduction
comparative fault ~ responsibility is proportional to respective party conduct
compartmentalization ~ dynamic tree defense process that forms boundaries
compensatory damages ~ damages for compensation to injury party for losses
competition ~ active demand of organisms for contested resources
complaint ~ paper which sets forth a civil plaintiff’s claims
compost ~ humus-rich soil created by fermenting/decomposing organic matter
compost heap ~ alternating layers of fresh & old organic matter to decompose
compound leaf ~ leaf possessing two or more leaflets
compression fork ~ expansion (and the resulting failure) due to trapped growth
compression wood ~ reaction wood in conifer root/branch/stem (leeward side)
concealed foreign object ~ inorganic body inside tree (i.e. metal, concrete, ect)
conduction ~ carrying water and elements
cone ~ seed-bearing structure of a gymnosperm (conifer)
conelet ~ immature cone
cone-scale ~ scale of a cone
confidentiality ~ duty not to reveal information which is obtained in confidence
conflict of interest ~ independent representation impossible due to prior facts
conifer ~ cone-bearing tree (see gymnosperm)
conk ~ substrate-projecting, fruiting body of wood decay fungus
conk rot ~ see red rot
conservation ~ sustained natural resource productivity
consulting arborist ~observes trees, draws conclusions & subscribes treatment
consulting forensic witness ~ assists one side in a dispute; does not testify
consulting report ~ oral/written presentation of a consulting arborist to client
container-grown ~ plant grown in a container
continuing education requirements ~ required to retain society membership
continuous pith ~ see solid pith
contributory negligence ~ participants of injury cannot recover damages
control ~ non-treated experimental unit
controlled-release fertilizer ~ see slow release fertilizer
cordate leaf ~ heart-shaped
cork cambium ~ meristematic tissue that develops cork and bark
corm ~ solid, underground stem; like a bulb without scales
corridor ~ linear land strip reserved for disturbance
cortex ~ primary plant tissue separating vascular & epidermis in stems & roots cost-effective ~ usefulness of specified inputs to produce specified outputs
cover ~ area occupied by vegetation
crack ~ circumferential & radial separations in wood and bark
cradle knoll ~ resulting pit and mound of a tree uprooting
crenate leaf ~ round-toothed margins
cricket canker ~ canker initiated by the boring of crickets
critical-risk tree ~ see extreme risk rating
critical root zone ~ land area 1 foot beyond dripline (crucial to tree survival)
crook ~ sharply-angled curvature in branch or stem (often due to loss of leader)
cross-pollination ~ transfer of pollen from one plant to another for fertilization
cross section ~ perpendicular sectional cut of wood
crotch ~ inward side of branch or stem attachment
crown ~ branch-bearing tree portion
crown class ~ relative individual tree size
crown cleaning ~ removal of diseased, dying, dead and dangerous branches
crown diameter ~ maximum and minimum crown width average
crown raising ~ providing clearance through lower branch removal
crown reduction ~ height/sides reduced to sufficiently-sized laterals (1/3)
crown restoration ~ restoring the natural crown shape of a mal-pruned tree
crown restructuring ~ see crown restoration
crown rot ~ advanced decay in plant crowns
crown thinning ~ selective removal of laterals to improve health and stability
cultivar ~ cultivated plant variety; group of closely related plants
cultivated ~ planted and maintained by man
cultural control ~ method of pest control through environmental changes
culture ~ artificial growth & propagation of organisms on nutrient media/plant
culture index ~ stem section culture on a defined medium to test for microbes
cumulative ~ collective effect over a period of time
cup shake ~ ring shake that circles the central portion of the stem
curative ~ pertaining to or used in the cure of diseases
cuticle ~ waxy, outside leaf epidermis layer
cytokinen ~ plant hormone involved with cell division
damping-off ~ stem rot of seedling (often the most serious nursery disease)
DBH ~ diameter at breast height (4.5 feet above natural grade average)
deadwood ~ any wood on woody plants, other than greenwood
deadwooding ~ see crown cleaning
decay ~ result of decomposition
decay column ~ contiguous, usually longitudinal, decayed area in a tree
decibel ~ unit of measurement of the intensity of sound
deciduous ~ annually leaf-shedding plant
decline ~ general reduced vigor of entire tree
decomposition ~ process of decay organisms breaking down organic matter
decurrent crown ~ lateral branch spreading tendency of a tree
defect ~ structural weakness in a tree
defendant ~ party against whom relief/recovery is sought in an action/lawsuit
deficiency ~ insufficient supply of minerals
defoliate ~ leaf loss
defoliator ~ leaf-consuming pest
demonstrative evidence ~ audio & visual presentations explaining testimony
dendrocronology ~ study of tree growth rings
dendrology ~ study of trees
dentate leaf ~ perpendicular tooth margins
den tree ~ tree with a weather-tight cavity that supports wildlife
depletion ~ natural resource demand exceeding supply
deposition ~ sworn, court-recorded testimony outside a courtroom
desert pavement ~ stony desert surface caused by excessive soil erosion
design criteria ~ site aspects and required plant function considerations
dessication ~ drying out of tissue
destructive testing ~ tangible items are disposed of during an examination
detention pond ~ temporary, flood containment basin
diameter ~ stem thickness (see DBH)
dicot ~ see dicotyledon
dicotoyledon ~ plant embryo having two seed leaves
dieback ~ progressive death of leaves, stems or roots; beginning at the tips
differentiation ~ specialized cell development
diffuse porous ~ uniform size and distribution of vessels (angiosperms)
dioecious ~ male and female flowers produced on separate plants
directional pruning ~ altering growth tendencies through removal of laterals
dirt ~ see soil
discolored wood ~ injury-altered wood; chemically-altered color (darker)
discoloring fungi ~ fungi associated with the coloring of wood
discontinuous ring ~ interrupted growth ring due to partial cambium dormancy
discovery ~ processes used before trail to uncover facts of the case
disease ~ deviation from normal functions (disruption, dysfunction or depletion)
disease complex ~ diseases resulting from two or more biotic agents
disease cycle ~ chain of events in disease development
disinfest ~ to kill disease organisms on the surface before infection
disinterested ~ free of self-seeking & personal bias; impartial & objective
dissemination ~ spread of inoculum from diseased to healthy plants
division ~ propagation by the separation of new plants from existing plants
dominant tree ~ crown extends above upper canopy layer
dormant ~ reduced physiological activity
dormant bud ~ bark subsurface bud more than a year old; sleeping bud
dorsal ~ belonging to or situated on or near the upper surface (of insects)
double-serrate leaf ~ toothed margins with smaller teeth within
down tree ~ tree lying on the ground
drainage ~ excess water removal
drainage tile ~ manmade tile or pipe, used to carry off excess water
drench ~ liquid poured on and through soil (pesticide or fertilizer)
drift ~ unintended pesticide movement
drill-hole fertilization ~ tree fertilization application method using a soil auger
drip irrigation ~ localized watering method that reduces run-off
drill-testing ~ small-diameter drilling into woody tissue to test for soundness
dripline ~ imaginary ground line, immediately below horizontal crown extension
drop-crotch pruning ~ see crown reduction
dropzone ~ hazard area where tree parts are dropped/lowered during removal
drought crack ~ radial stem split caused by wood shrinkage
drought tolerance ~ plant ability to postpone dehydration
drum-lacing ~ rootball-securing method of balled and burlapped trees
due care ~ performance level necessary to fulfill assignment requirements
duff ~ partially-decomposed organic matter beneath litter
earlywood ~ wood forming early in the growth season
earthing-up ~ protective mounding of soil over plant roots (sun, frost)
easement ~ an interest & right of use one entity has over another’s property
ecdysis ~ see molt
ecology ~study of inter-relationships between organisms and their environment
ecosystem ~ earth unit that includes all interacting organisms and components
ectomycorrhizae ~ beneficial root fungus, (often) visible mycelium strands
edema ~ swelling caused by excessive moisture; leaf or stem surface bumps
edge tree ~ forest tree at the edge of a recent forest clearing
elasticity ~ capacity of bodies to return to original shape
element cycling ~ soil element replacement by decomposition
element deficiency ~ sufficient essential element shortage to affect growth
elephant’s foot ~ bulging butt, resembling an elephant’s foot
elite sprout ~ rapidly-growing sprout, from a single bud
embedded bark ~ see included bark
emergency service restoration ~ allowable proper pruning deviation
emergent tree ~ crown completely above upper canopy layer
endemic ~ characteristic to a restricted area
endomycorrhizae ~ beneficial root fungus, grows between cell wall/membrane
end weight ~ mass concentration on branch end
energy ~ power that moves matter or drives natural processes
energy allotments ~ to distribute energy that best serves long-term survival
engagement letter ~ employment contract used by expert witness/consultant
enjoined ~ to require a person, by act of court, to abstain/desist from some act
entire leaf ~ toothless margins
environment ~ sum of all external conditions affecting organism survival
enzyme ~ protein molecule catalyst
epicormic ~ dormant/adventitious bud, shoot or branch arising from the stem
epidemic ~ dangerous pest outbreak
epidermis ~ outermost cell layer
epinasty ~ growth distortion
epiphyte ~ non-parasitic hitchhiking plant
eradication ~ elimination of an established pathogen from a planting area
erosion ~ wearing away of land surface by environmental conditions
escaped ~ initially spread by cultivation; now reproducing without human aid
ESP ~ exchangeable sodium percentage
espalier ~ training a tree or shrub to grow flat along a support
essential elements ~ any 1 of 16 required elements for plant growth
establishment ~ caring for a new planting until it becomes a landscape fixture
ethylene gas ~ naturally occurring plant hormone that triggers fruit ripening
etiology ~ the study of the causes or origins of disease
evaluation cycle ~ time period between scheduled hazard inspections
evapo-transpiration ~ plant moisture lost to evaporation and transpiration
evergreen ~ plants that hold their leaves for a long period of time
excavation ~ soil removal to required grade
excurrent crown ~ pyramidal tree growth tendency
exfoliating ~ peeling off by layers
exotic ~ introduced species, not naturally-occurring
expert ~ possesses special knowledge, skill or education in a particular field
expert opinion ~ experts are allowed to render opinions about what happened
expert testimony ~ verbal/written presentation; beyond knowledge of laymen
expert witness ~ person having special knowledge not held by general public
extra-high-strength cable ~ type of cable up to 3 times stronger than standard
extreme risk rating ~ failure is imminent & likely to hit target
exudation ~ oozing-out
face cut ~ notched cut used in felling trees
failure ~ defective tree part (or tree) loss
false crotch ~ branch lowering rigging device
false heartwood ~ age-altered wood primarily occurring longitudinally
false ring ~ later growth ring formed by growth interruption
family ~ group of related genera (taxonomic division under order)
fatigue ~ diminution of wood strength due to excessive loading
fatwood ~ abnormally-high resin in conifer wood (synonym lighterwood)
feathering ~ prolific sprouting; indicates threatened survival
fee simple ~ ownership of all land rights
felling ~ cutting down standing timber
fermentation ~ decomposition of carbohydrates in the absence of oxygen
fertilizer ~ essential plant element supplement
fertilizer analysis ~ nitrogen, phosphorus and potassium percentage
fertilizer burn ~ plant injury resulting from excessive fertilizer salts
fiduciary duty ~ to subordinate one’s interest to those of another (due care)
field capacity ~ soil moisture content following gravitational water drainage
filamentous ~ threadlike
filtrate ~ liquid which has passed through a filter
fill ~ see soil fill
final status conference ~ pretrial preparation process of a expert witness
fire blight ~ blight caused by a bacterial pathogen (can resemble fire injury)
fire scar ~ fire-accentuated plant injury
fitness ~ relative competitive ability
fleck ~ minute spot
flooding ~ incoming waterflow exceeds drainage
flower ~ reproductive organ of angiosperms (hardwoods)
flush cut ~ destructive pruning cut made within the branch collar
foliage ~ plant leaves
foliar analysis ~ laboratory analysis of foliage mineral content
foliar application ~ applied directly to foliage
food ~ any substance that provides the energy essential for life
foot rot ~ advanced butt decay
forcing ~ artificially inciting growth outside of normal growth season
forensic expert ~ provides expertise in court for the resolution of disputes
forest ~ an ecosystem characterized by dense & extensive tree cover
forester ~ one possessing the necessary skills to care for forests
forestry ~ the art and science of caring for forests
fork ~ usually the v-angle attachment of codominate stems and branches
form ~ see framework or architecture
FOT ~ foreign object in tree (nails, concrete, bricks, ect.)
foundation ~ factual/technical basis which supports expert opinion/testimony
fracture ~ see crack
fragmentation ~ process by which a landscape is broken down into islands
framework ~ basic structural design (for a tree; stem and scaffolds)
frass ~ wood fragments of borers or solid larval excrement of defoliators
friable ~ soil that is rich, light and easily worked with the fingers
frond ~ very large, divided leaf (of palms & ferns)
frost crack ~ wood separation of predisposed wood during cold weather
fruit ~ seed-bearing organ of a flowering plant (ripened ovary)
fruiting body ~ fungus spore-bearing organ (synonym mushroom or puffball)
Frye rule ~ expert opinion must have a reasonable degree of acceptance
fuelwood ~ firewood
full-fluted drill bit ~ full length fluting to facilitate drill-testing
fumigate ~ to apply a vapor-active disinfectant to kill/control pests
fungal mat ~ dense mass of fungi mycelium
fungicide ~ chemical that controls/kills fungi
fungus ~ nongreen, nonvascular, tubular, filamentous plant
gall ~ localized plant tissue swelling (synonym burl)
galleries ~ see wood galleries
generating system ~ upon shedding, new parts are formed in new positions
generation ~ period of time required to complete an insect life cycle
genetics ~ the study of heredity (especially organism traits & characteristics)
genus ~ fundamentally similar group of species (above species/below family)
geotropism ~ growth response to gravitational force
germination ~ seed or spore rupture and seedling emergence
germ tube ~ hypha resulting from an outgrowth of the spore wall or cytoplasm
gibberellin ~ plant hormone involved in cell elongation
girdling ~ stem or buttress root constriction; to encircle
glasphalt ~ type of durable asphalt which uses crushed glass instead of sand
grading ~ intentionally raising or lowering the natural soil grade
grading contractor ~ one who alters site elevation to conform to grading plan
graft ~ placing a plant in close cambial contact with another plant
graft crack ~ crack that forms after wood dries out from improper grafting
grain ~ wood fiber direction relative to the stem axis
gravitational water ~ water that drains from the soil
green manure ~ the bodies of green plants that have been plowed under soil
greenwood ~ any wood on woody plants, other than diseased or dead wood)
ground cover ~ herbaceous plants and lowest scrub occupying an area
grounded ~ electrically connected to the earth
ground rod ~ 10-foot copper rod used to ground a lightning protection system
ground water ~ water that has infiltrated the ground (vs. runoff water)
gouting ~ tumorlike swellings caused by the feeding of sucking insects
growth crack ~ shallow, longitudinal bark separation
growth regulator ~ plant growth-modifying hormone
growth ring ~ distinctive, annually cumulative, wood cell layering
guard cells ~ cells that regulate a stomate
gully reclaimation ~ the mending of a gully; either physically or by vegetation
gummosis ~ gum exudation of trees (especially cherry, peach & plum)
guying ~ temporarily securing an unstable tree to the ground with lines
gymnosperm ~ flowering, vascular plant, with exposed seeds (conifer)
habitat ~ place where animals, plants or people normally live and develop
habitat fragment ~ remnant of wildlife habitat
hanger ~ broken or detached, lodged tree part
hardening-off ~ increasing indoor plant adaptability for outdoors
hardiness ~ plant cold-tolerance
hardiness zones ~ predetermined regions separated by hardiness
hardscape ~ asphalt or concrete landscape paving
hardwood ~ see angiosperm
harvesting ~ felling, skidding, loading and transporting logs (synonym logging)
hazard ~ assessed defective tree that presents a danger to life and/or property
hazard abatement ~ reducing or eliminating a hazard
head ~ first region of an insect body (eyes, mouth parts & antennae)
heading ~ see topping
heal collar ~ see branch collar
health ~ the ability to resist strain
hearsay ~ statement made by a witness outside of the trier of fact
heart rot ~ advanced heartwood decay
heart shake ~ wood separations in the center of the stem
heartwood ~ age-altered, protective wood, between sapwood and pith
heartwood rot ~ advanced heartwood decay
heat island ~ confined, urban, heat-absorbing area
heaving ~ lifting of soil/roots by alternating freezing and thawing conditions
hedge ~ living fence of shrubs (usually uniformly sheared)
hedgerow ~ narrow band of trees and shrubs that divide two open areas
heeling-in ~ protective soil covering of plants until more favorable conditions
held out ~ offered or presented as or represented or warranted to be
herb ~ plant with a soft, non-woody stem, drying to ground winter
herbaceous ~ pertaining to plants that do not develop much woody tissue
herbicide ~ pesticide for killing/controlling plants
high grading ~ harvesting the best forest crops, leaving the worst
high-impact felling ~ felling tree or tree parts directly to unprotected surface
high-risk tree ~ failure may occur during increased loading
hinge ~ area of wood between face cut and back cut, used to control felling
hip canker ~ localized, lower stem depression (usually of pines by rust fungi)
holding wood ~ see tension wood
hollow ~ enclosed tree cavity; result of advanced decay
hollow pith ~ twig with a space where the pith should be
home range ~ total area occupied by an animal during its life cycle
honeycombing ~ small lenticular separations in wood
honeydew ~ sticky secretion of sucking insects (particularly aphids & scales)
hook and blade pruner ~ see bypass pruner
horizon ~ soil profile layer (A, B, C, D & E)
hormone ~ organic chemical transported from one organism part to another
host ~ organism that sustains another organism
host range ~ various plants which a pathogen can infect
hummock ~ small, rounded rise of organic matter
humus ~ dark, microbial breakdown of plant and animal residue
hybrid ~ offspring of genetically different parents
hydroculture ~ see hydroponics
hydrogel ~ water-absorbing, crystalline polymer
hydrologic cycle ~ circular movement of water from ocean, to clouds, to rain
hydroponics ~ growing plants in a water/element medium (vs. soil medium)
hyperparasites ~ organisms that parasitize pathogens
hypothesis ~ rational configuration of assumed facts subject to specific proof
immune ~ not affected by or responsive to disease
impartial ~ favoring neither side; treating all alike; being unbiased or equitable
impervious cover ~ land cover greatly-limiting infiltration (asphalt, concrete)
implant ~ stem-inserted pellet used to treat disorders
included bark ~ bark embedded in closely-angled stem & branch attachments
incidence ~ degree or range of occurrence
increment ~ annual girth increase of plant branch, stem or root
increment borer ~ xylem core extracting auger
independence ~ freedom in fact & appearance from prejudicial influences
indicator tree ~ representative of other trees on a site
indigenous ~ specified area native
infection ~ establishment of a feeding relationship between host/parasite
infection court ~ pathogen infection site
infestation ~ considerably-concentrated pest attack
infiltration ~ downward entry of water into soil
infiltration rate ~ infiltration speed
injunction ~ judicial order directing a person to do/refrain from an act
injury ~ see wound
inoculate ~ to place inoculum in an infection court
inorganic ~ non-living matter
inorganic fertilizer ~ mineral fertilizer not derived from plants & animals
insect ~ adult characterization of a body with a head, thorax & abdomen
insecticide ~ pesticide used to kill/control insects
insoluble ~ will not easily dissolve in water
installation ~ setting a plant into the ground to grow
instar ~ life stages of an insect larva between molts
integrated pest management ~ biological, chemical and cultural pest controls
integrity ~ quality of being candid, sincere, honest & of a sound moral principle
intercellular ~ between or among cells
interception ~ canopy seizure of precipitation
interface ~ space between two landscape surfaces
intermediate tree ~ crown extends into lower portion of upper canopy
internode ~ between two successive nodes
interveinal tissue ~ leaf tissue between veins
intracellular ~ within or through a cell or cells
introduction ~ installation of nursery stock into an established landscape
inundate ~ see flooding
in vitro ~ in an artificial environment; in a glass
in vivo ~ within a living organism
ion ~ electrically-charged molecule
IPM ~ integrated pest management
irruption ~ sudden organism population increase; followed by a steep decline
ISA ~ International Society of Arboriculture
isolate ~ microbe culture separated/confined to a pure culture
joint & several liability ~ harmed person can recover damages from either party
juvenile ~ immature plant having not reached breeding age
kernel ~ inner, softer part of a seed, fruit stone or nut
key ~ dry, one-seeded fruit with a wing
kingdom ~ primary division between plants and animals in taxonomy
kino veins ~ outer cambium barrier zone that forms as the result of injury
land developer ~ one who acquires unimproved land & prepares it for use
landfill ~ method of solid waste disposal; dumping, compacting & soil-covering
land planner ~ one who develops conceptual land-use plans & feasibility
landscape ~ defined land area, designed for human use and enjoyment
landscape architect ~ one who develops theme & designs plans for landscapes
landscape contractor ~ one who installs plants to conform to landscape plans
land trust ~ non-profit entity/private landowner mutually-beneficial relationship
larva ~ immature life stage of an insect
latent ~ present but not manifested or visible
latent bud ~ see dormant bud
lateral ~ side or offshoot branch
lateral branch ~ see lateral
lateral bud ~ vegetative bud on the side of a stem
lateral root ~ side-branching root that grows horizontally
latewood ~ xylem wood forming late in the growing season
leach ~ tendency for elements to wash down through soil
leader ~ topmost shoot
leaf ~ major energy-trapping organ of plants
leaf apex ~ blade tip
leaf base ~ blade bottom
leaf blotch ~ irregular-shaped, diseased area on foliage
leaf cast ~ untimely foliage shedding
leaf framework ~ midrib and vein scaffolds
leaflet ~ single compound leaf blade
leaf margin ~ outer leaf blade edge
leaflet midrib ~ leaflet axial vein
leaf midrib ~ leaf axial vein
leaf scar ~ twig scar left from abscission
leaf sinus ~ space between two leaf lobes
leaf spot ~ see spot
leaf stalk ~ leaf-supporting stem (synonym petiole)
leaflet stalk ~ leaflet-supporting stem (synonym petiolule)
lean ~ departure from vertical
learned treatise ~ publication which is considered authoritative in a field
leave tree ~ marked tree left standing for wildlife/seed production
leeward ~ lean side of tree
legacy tree ~ aged tree retained as a biological heritage
lenticel ~ bark opening permitting gas exchange
lesion ~ well-marked, localized diseased area
lethal ~ fatal; causing death
leveling ~ grading surface prior to fill
licensee ~ person granted permission by owner to enter/remain on land
lichen ~ symbiotically-related fungus/alga composite
life cycle ~ sequence of developmental growth stages in an organism
lighterwood ~ see fatwood
lightning protection system ~ unit that safeguards trees from lightning injury
lignin ~ complex polymer that binds cellulose units (the “glue” of wood cells)
limb ~ see branch (sometimes called a large branch; we make no distinction)
limiting factors ~ any factor in the environment that limits organism growth
liquid injection ~ soil-injected liquid tree fertilizer
litter ~ non-decomposed tree shedding debris
live-crown-ratio ~ relative green crown proportion
living fence ~ shrub/tree strip forming property boundary
loading ~ applying external force to a structure
loam ~ ideal soil containing near equal parts of sand, silt and clay
lobe ~ projecting leaf blade segment
lodged tree ~ tree that’s lost anchorage, coming to rest in another tree
log ~ down tree stem/scaffold, debranched, of a determinate length
logging ~ see harvesting
loose heart ~ see cup shake
lopping ~ see topping

low-impact felling ~ controlled lowering of tree or tree parts to surface
low-risk tree ~ failure is unlikely in the immediate future
macroelement ~ essential plant element required in large quantities
macroinjection ~ large amounts of chemical directly injected into sapstream
macronutrient ~ see macroelement
macropore ~ soil space larger than .002 inch in diameter, usually air-filled
maintenance ~ keeping an established landscape in an existing state
mal-pruning ~ destructive pruning habits
manure ~ animal refuse (usually of stables and barnyards)
marl ~ earthly deposit of calcium carbonate, usually mixed with clay
marsh ~ water-saturated, poorly-drained, peat-less wetland (salt or fresh)
masked symptoms ~ symptoms appearing only under certain conditions
mature ~ sexually reproductive tree having nearly reached its potential height
mediation ~ method of dispute resolution in which an impartial 3d party assists
meristem ~ undifferentiated tissue, where active cell division takes place
metabolism ~ the multitude of processes that maintain life
metamorphosis ~ series of developmental changes in insects, from egg to adult
microbial insecticide ~ microorganisms applied to plants for insect control
microbe ~ see microorganism
microburst ~ sharp, forceful updrafts (major cause of branch fractures)
microclimate ~ climate within a small, specific area
microelement ~ essential plant element required in small quantities
microflora ~ composite of microscopic plants
microinjection ~ small amounts of chemical directly injected into sapstream
micronutrient ~ see microelement
microorganism ~ organism too small to been seen by the unaided eye
micropore ~ soil space smaller than .002 inch in diameter, usually water-filled
microscopic ~ too small to been seen by the unaided eye
midrib ~ see leaf or leaflet midrib
mildew ~ plant disease characterized by a thin coating of mycelial growth
MLO ~ mycoplasmalike organism
mineral streak ~ vertical columns of discolored wood (associated with wounds)
minimum irrigation ~ supplemental watering only during drought
miticide ~ pesticide the controls/kills mites
mixed stand ~ group of trees dominated by two or more like-species
moderate-impact felling ~ felling tree or tree parts to a protected surface
moderate-risk tree ~ failure may occur during excessive loading
moisture sensor ~ shuts down irrigation at a programmed soil moisture level
mold ~ profuse fungal growth
molt ~ shedding of the outer skin or cuticle
monocot ~ see monocotyledon
monocotyledon ~ plant with a one seed leaf embryo
monoecious ~ plant with both sexes
moonrings ~ colored heartwood bands that may spread about heartwood core
morphology ~ study of plant part shapes
mortality ~ average age of death due to natural causes for a given species
mosaic ~ disease symptom characterized by mottling or variegated patterns
mottle ~ disease symptom characterized by irregular light/dark patterns
muck ~ highly-decomposed organic soil (more complete than peat)
mulch ~ applied, loose, organic/inorganic soil surface covering
multiple infection ~ invasion of a host by more than one parasite
mushroom ~ see fruiting body
mutation ~ abrupt heritable change in an individual
mycelium ~ mass of fungal filamentous cells
mycoparasitism ~ parasitism of one fungus on another of a different species
mycoplasma ~ microscopic plants (intermediate size between bacteria/viruses)
mycorrhizae ~ beneficial, symbiotic root fungi on/in fine, nonwoody roots
NAA ~ National Arborist Association
native species ~ species present prior to european settlement
natural condition ~ condition not the result of any human activity
natural forest ~ naturally-occurring forest, not planted or managed by man
naturalized ~ non-native successfully established and reproducing naturally
natural pruning ~ natural branch dying and shedding
natural resource ~ any component of the natural environment useful to man
natural target pruning ~ pruning cuts made just outside the branch collar
necrosis ~ localized plant tissue death
needle ~ slender conifer leaf
needle cast ~ untimely needle shedding
needle sheath ~ needle base tissue that binds together the needles
negligence ~ failure to use such care as a reasonably prudent person would
negligence per se ~ conduct which may be declared negligent without proof
nematicide ~ pesticide that controls/kills nematodes
nematode ~ microscopic, parasitic, wormlike animals; moving freely in soil
neutral soil ~ soil near 7.0 soil pH (not sour or sweet)
niche ~ the place within the habitat of an organism necessary for survival
nip-back ~ pruning the plant tip to encourage lateral growth
node ~ slightly enlarged stem area, where flowers/leaves/branches arise from
nomenclature ~ naming system
nonpathogenic ~ unable to cause disease (synonym avirulent)
noxious plant ~ plant legally identified as troublesome
nuisance ~ unlawful/unreasonable use of own property injuring another owner
nurse tree ~ tree that aids in the growth of adjacent tree (s)
nut ~ dry fruit or seed, with a hard shell and firm inner kernel (kernel as well)
nutlet ~ 1 of several small, nut-like parts of compound fruit, containing a seed
nutrient cycling ~ see element cycling
nymph ~ young stage of an insect (similar in form to the adult)
objectivity ~ concerned with reality, facts & reasonable assumptions
obligate ~ species that is limited to its specific habitat
oblique leaf ~ lop-sided
obtuse leaf ~ rounded, semi-circular
occupancy rating ~ level of use by people of a potential target
ocedema ~ watery plant tissue swelling
old-growth forest ~ late-successional stage of undisturbed, usually-virgin forest
open grown trees ~ spaced so their crowns are not growing together
opposite ~ two opposing leafs at each node
order ~ taxonomic division between class and family
ordinance ~ method of enacting laws by municipalities
organic fertilizer ~ fertilizer derived from plants/animals
organic layer ~ organic matter on soil surface
ornamental ~ any ornamental plant grown to beautify a landscape
osmosis ~ water diffusion through plant membrane
ovary ~ female flower part that develops fruit
overfertilization ~ excessive mineral application (especially nitrogen)
overmature ~ declining mature tree reaching the end of its natural life span
overskirting ~ over-raising and/or overthinning the lower crown
overstory ~ uppermost canopy in a multi-storied forest or woodland
overtapping ~ extensive tapping, leading to tree decline
over-thinning ~ excessive green lateral removal
overtopped tree ~ see suppressed tree
overwinter ~ to survive the winter
ovulate ~ having seed-bearing organs only
ovule ~ where seeds develop in an ovary
palmate leaf ~ radiating, fan-like, compound leaf
parasite ~ organism that subsists from another living organism
parenchyma ~ vertically or horizontally arranged living, food-storing wood cells
parent branch ~ see stem
parent limb ~ see stem
parent material ~ soil bedrock material
parthenogenesis ~ reproduction without male fertilization
pathogen ~ causal disease agent
pathology ~ the science of the essential nature of disease
pavement base ~ porous, compacted rock and/or gravel
PDA ~ personal digital assistant (handheld computer)
PDR ~ purchase of development rights
peal ~ bark separation from tree (usually a tear)
peat ~ organic soil material, with recognizable original plant parts
pencil rot ~ rot column/hollow associated with dead branches (cedar/cypress)
penetrometer ~ instrument used to measure physical soil compaction
percolation ~ downward movement of water through soil
perennial ~ plant that requires more than 2 years to complete its life cycle
periderm ~ secondary tissue of stems/roots (phellem, phellogen & phelloderm)
permafrost ~ permanently frozen soil in tundra/artic regions
permanent wilting point ~ point at which a plant can no longer derive water
permeability ~ ease with which gases, liquids & roots penetrate soil
pest ~ plant-injurious organism
pesticide ~ chemical used to kill/control pests
petiole ~ see leaf stalk
petiolule ~ see leaflet stalk
petri dish ~ culture container
pH ~ logarithmic measure of acidity/alkalinity soil properties (scale of 0 to 14)
PHC ~ plant health care
pheromone ~ insect hormone sexual attractant
phloem ~ food-conducting tissue of plants
phorophytes ~ host plant used by epiphytes for support
photoperiod ~ required length of daylight for plant growth
photosynthesis ~ food-making process in green plant foliage
phototropism ~ plant growth influenced by light
phylum ~ primary taxonomic division within kingdom
physiological disorder ~ non-pest plant problem (usually urban stress)
physiology ~ study of plant life function
phytotoxic ~ poisonous to plants
pigment ~ substance that appears colored due to light wavelength absorption
pinnate leaf ~ compound leaf with leaflets along each side
pioneer ~ new plant arrival in the early stages of succession; lichens, weeds
pioneer pathogen ~ aggressive organism that opens the host’s defense barriers
pioneer root ~ large, long lateral root, with few or none second-class roots
pipet ~ plastic/glass tube used to transfer measured amounts of liquid
pitch ~ see resin
pitch tube ~ projecting, conifer resin cylinder (often incited by bark beetles)
pith ~ stem or branch central core
plaintiff ~ person who brings a lawsuit or action for injuries to his rights
plant ~ cellulose-celled, living organism, without locomotion or sense organs
planted forest ~ forest, the majority of which, is planted by man
plant growth regulator ~ see plant hormone
plant health care ~ prescribed plant care through periodic diagnostics
plant hormone ~ plant substance that affects growth
planting ~ see installation
plow ~ see till
pocket rot ~ small pockets of rotted wood surrounded by solid wood
pod ~ dryish fruit (especially legumes), usually with flattened and split seeds
podzol soil ~ grayish, acidic, often infertile soil, developing under forest cover
pollard ~ close head of shoots
pollarding ~ annual, radical pruning back to pollards, to regulate tree growth
pollen ~ mass of pollen grains
pollen grain ~ microscopic, tree sperm particle (often yellow)
pollen-sac ~ part of an anther containing the pollen
pollination ~ pollen deposition on a receptive female flower or cone
population ~ total number of individuals of a species occurring in a given area
porosity ~ relative soil pore volume
powdery mildew ~ white or grayish fungal growth on foliage surface
PPD ~ people pressure diseases (see urban tree decline)
prairie ~ near-level, treeless, usually featureless, fertile grassland
precipitate ~ insoluble compound formed by the chemical reaction of solubles
precut ~ stub-cutting a branch prior to natural target pruning to prevent tearing
predator ~ aggressive organism that externally feeds on other organisms
predisposed tree ~ environmentally weakened, susceptible tree
preliminary opinion ~ first stage of an expert witness’s opinion-forming process
prescribed burning ~ type of controlled, beneficial, forest floor burning
prescription ~ acceptably-ranged, planned treatment of specific health problem
prickles ~ slender, sharp outgrowths of stem tissue beneath the epidermis
primary elements ~ nitrogen, phosphorus & potassium
primary host ~ principle host where the sexual form is found
primary succession ~ ecological succession developing in an unoccupied area
privilege ~ communication between parties unreachable by opposition party
pro bono ~ (latin) for the public good; services provided free of charge
producer ~ plant that produces its own food (vs. parasites)
profession ~ occupation based on an organized body of specific knowledge
professional ethics ~ principles promulgated by entities to guide entity conduct
professionalism ~ to know, do & support at a high level a chosen field/activity
professional negligence ~ professional failure of reasonable standards of care
profile ~ treated experimental unit
propagate ~ reproduction by sexual or vegetative (asexual) means
prop root ~ see stilt root
protectant ~ pesticide that prevents pest establishment on host surface
protection wood ~ wood altered to a higher state of protection
protection zone ~ formed at the base of dying or properly pruned branches
prothorax ~ first thoracic segment bearing the first pair of legs (no wings)
protocol ~ series of steps usually followed in a technical or specialized area
prudence ~ carefulness, attentiveness & good judgment applied to act/conduct
pruning ~ unwanted plant part removal; control size, shape, fruiting & flowering
pruning lift ~ crown raising to a specified height or branch diameter
public interest ~ collective well-being of the community served by a profession
public trust ~ public trust or acknowledgement in the expertise of experts
PUD ~ planned urban development
punitive damages ~ damages other than compensatory; awarded to punish acts
punk ~ spongy (often wet) wood caused by advanced decay
pupa ~ immature, immobile insect stage, between larva and adult
pupate ~ to become a pupa (pass through a pupal state)
pure stand ~ group of trees dominated by 80 % (or more) like-species
quarantine ~ legislative control of plant transport to control disease
radial branch spacing ~ relative branch distance around stem
radial trenching ~ shallow excavations radiating out from a tree (to fertilize)
rain shadow ~ area that receives less rain due to a high land mass
rain shutoff device ~ inhibits irrigation at a predetermined amount of rainfall
raising ~ see crown raising
ram’s horn ~ inward rolling of woundwood, often preventing wound closure
range ~ area where plants naturally reproduce
rapid taper zone ~ root growth area with rapidly-diminishing diameter
ray ~ distinctive, radially-extending tissue, across tree xylem and phloem
ray shake ~ radial wood separation following radial parenchyma
reaction wood ~ wood altered as a response to lean
reaction zone ~ protective chemical boundary about developing infected wood
reagents ~ solutions used in the analysis of soils and plant tissues
reasonable care ~ degree of care which a prudent person would exercise
reasonable foreseeability ~ reasonable anticipation that injury is a likely result
reasonable man standard ~ what a reasonable man would do under like-factors
reasonable probability ~ degree of certainty needed to support expert opinion
red rot ~ advanced, reddish-brown heartwood decay by the white rot fungus
rehabilitative pruning ~ selective sprout removal to rehabilitate topped trees
related consulting ~ consulting in fields related to arboricultural consulting
remnant forest ~ fragment of preexisting forest
report ~ see consulting report
request for admission ~ a party requests the other party to admit known facts
request for production ~ written request to a party to produce documents
residual stand ~ group of trees remaining after intermediate harvest
resin ~ water-insoluble, gummy xylem fluid or exudation (of conifers/gums)
resin duct ~ enlarged parenchyma cell; mostly axial, in conifer latewood
resinosis ~ resin exudation of conifer wounds
resistance ~ tendency to withstand disease
resistance breeding ~ selection & propagation of pest-resistant individuals
resistograph ~ drill-testing instrument that measures wood soundness on paper
respiration ~ plant process of converting carbohydrates into energy (burning)
response ~ resulting action or answer from a stimulus
restoration ~ returning an ecosystem or habitat to its original state
restoration pruning ~ see crown restoration
retained tree ~ see retention
retaining wall ~ soil-bearing structure to support fill or retain natural grade
retention ~ leaving desirable remnant trees during land development
retention pond ~ runoff containment basin for recharging ground water
rhizome ~ underground stem from which new plants grow from the nodes
rhizomorph ~ thick mycelium strand, non-individualistic hyphae (root-like)
rhizosphere ~ immediate, fine root environment
rhizotron ~ windowed chamber for observation and research of root growth
right-of-way ~ see easement
ring-porous ~ well-defined, large-diameter pores in earlywood (angiosperms)
ring rot ~ column of ring-shaped advanced decay (usually of conifer branches)
ring shake ~ circumferential wood separation following a growth ring
ring spot ~ disease symptom characterized by yellowish or necrotic rings (viral)
rip cut ~ top cut made without prior under-cut, often resulting in branch tearing
risk assessment ~ risk identification, analysis & evaluation
rogue ~ hand remove/destroy individual, pest-infested or diseased plants
rootball ~ tree root/soil containment
root barrier ~ controls growth by trapping, constricting, deflecting or inhibiting
root cap ~ non-meristematic root tip covering
root channel ~ soil cavity left by decomposed root
root channeling ~ use of barriers to direct roots to desired area
root collar ~ see root crown
root crown ~ converging stem/buttress root area
root crown inspection ~ extensive, physical root crown examination
root flare ~ upper buttress root, normally exposed on natural grades
root growth control barrier ~ see root barrier
root hair ~ microscopic, modified, epidermal root cell protuberance
root pruning ~ indiscriminate root cutting during construction (see beneficial)
root zone therapy ~ prescribed remedy for soil problems within plant root zone
rot ~ obvious, advanced decay
rub tree ~ left tree to protect other trees from skidding injury during harvesting
rules of evidence ~ rules that determine what is & is not admissible in disputes
runner ~ long, slender trailing stem that can take root and produce new plants
runoff ~ non-intercepted precipitation (especially on slopped, compacted soils)
rust ~ (often rust-colored) obligate, fungal pustules or cankers on green plants
SAF ~ Society of American Foresters
salinity ~ relative concentration of salts in soil or water
samara ~ see key
sand ~ very coarse soil, with mineral particles .002 – .08 inch in size
sanitation ~ see crown cleaning
sap ~ soluble, aqueous vascular fluid/exudation (mostly hardwoods)
sapling ~ young tree, larger than a seedling, smaller than a juvenile
saprophyte ~ organism that feeds solely on dead organic matter
sapstreak ~ star-burst pattern of discolored wood in infected cross-section
sapwood ~ dynamic, water & mineral-transporting, outer xylem wood
sapwood rot ~ advanced sapwood decay
SAR ~ sodium absorption ratio
savanna ~ subtropical, level, lowland area (grassy or woody)
SCA ~ Society of Commercial Arborists
scaffold ~ primary structural branch (usually directly attached to stem (s))
scald ~ superficial necrosis of epidermal tissue (forming large spots)
scale ~ thin, membrane-covering of the bud or twig base
scavenger ~ see saprophyte
scion ~ shoot/bud that is implanted/grafted to a rooted plant for propagation
SCISA ~ Southern Chapter International Society of Arboriculture
scorch ~ leaf shriveling and browning
screen ~ shrub or tree strip that filters noise, light and objectionable scenes
scribing ~ see wound scribing
scrub ~ stunted trees or shrubs with low economic value
SCUCFA ~ South Carolina Urban & Community Forestry Council
secondary host ~ host of which only asexual reproduction occurs
secondary pest ~ pest that primarily attacks predisposed plants
second-growth forest ~ subsequent emerging forest
sedentary ~ remaining in a fixed position
seed ~ ripened plant ovule
seedling ~ emerging plant from a seed, smaller than a sapling
seed tree ~ tree left for seed production
segment ~ subdivision of an animal body or appendage
selective cutting ~ harvesting only trees ripe for market
self-corrected lean ~ reestablishing the center of gravity
self-pruning ~ see natural pruning
serrate leaf ~ forward-pointing, sawtooth margins
shade intolerant ~ light-demanding plant
shade tolerant ~ plant that reproduces well under reduced light conditions
shade tree ~ urban, medium to large broadleaf, usually with a decurrent crown
shake ~ separation of wood in trees (see ring or ray shake)
shall ~ mandatory ANSI Standards requirement
shearing ~ evenly clipping back the outer foliage of shrubs and trees
shedding ~ separate one tree part from another (from abscission to dieback)
sheet irrigation ~ type of irrigation in which surface water flows like a sheet
shelter belt ~ rows of trees/shrubs arranged to reduce desiccation & erosion
shepherd’s crook ~ sharply downward-curved branch or stem (known defect)
shigometer ~ instrument that detects wood decay by electrical resistance
shoot ~ young, tender, actively-growing, aerial outgrowth from a plant body
shothole ~ leaf with small holes (necrotic leaf spots have fallen out)
should ~ advisory ANSI Standards requirement
shoulder wood ~ see branch collar
shrub ~ woody plant lacking a dominate stem; rarely over 15 feet in height
side pruning ~ removal of laterals to provide right-away clearance
sign ~ visual manifestation of an agent that causes a problem (see symptom)
silt ~ intermediate soil, with mineral particles .00008 to .002 inch in size
siltation ~ the filling up of a body of water with water-borne sediment
simple leaf ~ single, one-part leaf
sink ~ plant part that is an energy drain to the whole system
sinker root ~ downward growing root
sinus ~ space between leaf lobes
site analysis ~ determination of plant conditions, needs and environment
skeletonizer ~ leaf-consuming pest that leaves the leaf framework
skid ~ to drag or haul a down tree or log, from stump to skid yard
skid road ~ access cut through the forest for skidding (synonym twitch trail)
skid yard ~ log collection and loading site
slash ~ forest residue from storm or harvest
slime flux ~ (often foul-smelling) discharge of bacterial wetwood
slime mold ~ fungus-like organism (possessing animal & plant characteristics)
slit planting ~ installing seedlings into a soil cut; closing with foot pressure
slope ~ measured change in surface elevation
slough ~ low, swampy, slow-draining ground
slow-release-fertilizer ~ coated fertilizer that releases nitrogen slowly
SMA ~ Society of Municipal Arborists
snag ~ standing dead tree (at least 6’ high) without leaves and most branches
soft rot ~ the digestion of the middle layer of the secondary cell wall
soil ~ plant growth medium of unconsolidated minerals and organic matter
soil amendment ~ additive that improves soil properties
soil analysis ~ laboratory test to determine mineral composition and pH
soil auger ~ soil core removing device
soil compaction ~ see compaction
soil consistency ~ soil ability to resist deformation
soil core ~ cylinder section showing horizons
soil cut ~ removing soil to a desired elevation
soil density ~ soil weight relative to volume
soil engineer ~ one who assesses soils & prepares specifications for soil work
soil fill ~ placing soil to a desired elevation
soil fire ~ smoldering fire that consumes organic materials in soil subsurface
soil horizon ~ see horizon
soil mounding ~ raised earth due to lost root anchorage on the windward side
soil plasticity ~ ability of clay to be molded
soil profile ~ cross-sectional view showing horizons
soil retaining wall ~ see retaining wall
soil strength ~ load-supporting ability
soil stripping ~ vegetation and topsoil removal
soil structure ~ soil particle arrangement
soil texture ~ relative particle size
solar energy ~ radiant energy generated by the sun
solen ~ see runner
solid pith ~ continuous pith in twig center, neither chambered, nor hollow
sooty mold ~ dark, velvety, mycelium plant coating (growing in honeydew)
sorting ~ to arrange or separate according to similar characteristics
sounding ~ striking woody tissue (with a mallet) to acoustically test soundness
source ~ carbohydrate-producing plant part
sour soil ~ acidic soil (below 7.0 soil pH)
sp. ~ species (plural spp.)
sphagnum ~ fibrous, moss-like plant material (used for its water holding ability)
sparsely vegetated ~ less than 10% vegetative cover
species ~ group of similarly-reproducing organisms
specimen ~ sample that is typical of the group or whole
specimen tree ~ preserved, usually mature, representative of a species
spider-heart ~ see star shake
split ~ see crack
spoil bank ~ mounds of overburden that accumulate during strip mining
spore ~ propagative fungi body
sporophore ~ see fruiting body
spot ~ limited, circular to oval, chlorotic or necrotic area on a leaf/plant part
spraying ~ act of broadcasting plant parts with atomized pesticide or fertilizer
springwood ~ see earlywood
sprout ~ adventitious shoot
spur ~ short side twig, often bearing a cluster of leaves
stag-headed ~ dead branches protruding through a live crown
stain ~ discolored sapwood caused by fungi
stalk ~ see leaf stalk
stalking ~ supporting a newly-installed plant
stand ~ group of like-species trees, somewhat uniform in size
standard down conductor ~ lightning protection system copper cable
standard of care ~ reasonable degree of care required of prudent professionals
standards of practice ~ guidelines promulgated by professional societies
stand average height ~ average height of all the trees in a stand
standing dead tree ~ free-standing dead tree, of at least breast height
starch ~ complex carbohydrate (reserve plant food)
star shake ~ radial cracks spread outward from a circumferential shake
statute ~ act of legislature declaring, commanding or prohibiting something
stem ~ principal woody plant axis, from which buds and shoots develop
stem analysis ~ complete stem examination of growth rings, taper & volume
stem bark ridge ~ ridge created when adjoining stems push bark outwards
stem injection ~ deliberate chemical introduction into the sapstream
sterility ~ sexual reproduction dysfunction
stilt root ~ aerial root that has taken root in the ground and grown into a prop
stimuli ~ agent or action able to incite a response in an organism
stimulus ~ plural of stimuli
stippling ~ speckled or dotted areas
stomata ~ small, leaf or stem pore, that permits gas exchange
stool ~ living stump (usually sprouted)
strain ~ injurious, irreversible, energy blockage, disruption or drain
strangulation ~ physical girdling
stratum ~ distinctive canopy layer
strain ~ necrosis along vascular bundles in leaves or stems
stress ~ natural processes beginning to function at limits of available energy
stringy rot ~ advanced, strand-like, fungal decay
strip mining ~ physical (by machine) removal of surface ore; leaving ugly scars
strobilus ~ see cone
stroma ~ compact vegetative structure (on or within fruiting bodies are formed)
structural integrity ~ soundness of a structure (framework) to remain upright
structural roots ~ see buttress roots
smut ~ fungus with sooty spore masses
stubbing ~ see topping
stub cut ~ destructive pruning cut made away from the branch collar
stump ~ in-ground remains of a felled tree (usually less than breast high)
stumpage ~ commercial value of timber as it stands
stump cutting ~ see stump grinding
stump grinder ~ gas/diesel-powered machine used to shred stumps into mulch
stump grinding ~ stump removal using a stump grinder (to below ground)
stump removal ~ stump expulsion by grinding, extracting, blasting or burning
stump sprout ~ dormant bud or adventitious shoot from a tree stump
stunting ~ suppressing plant growth
suberin ~ waxy material that coats the inside walls of the outer bark or phellem
subbase ~ replacement fill
subgrade ~ graded, compacted native soil
subjective ~originating from/influenced by one’s personal interests/prejudices
subsoil ~ that layer of soil normally found under topsoil
subspecies ~ organism intermediately between species and variety
subtropical forest ~ regional forest, averaging above 50 degrees (F) 5-8 months
succession ~ gradual supplanting of one organism community for another
sucker ~ shoot arising from below ground (root or rhizome)
sudden limb drop ~ sudden branch failure (often on a warm, windless day)
sunscald ~ scald caused by sudden exposure to light (of foliage or bark)
supplement ~ element additive to remedy deficiency
supporting root ~ woody root that anchors a woody plant to the ground
suppressed sprout ~ short-lived, slow-growing watersprout
suppressed tree ~ crown is completely canopy-covered
susceptibility ~ inability to withstand pest attack
sustainability ~ forest capacity to maintain health & integrity for the long run
swamp ~ slow-moving, above-ground water, near neutral pH, peat-less land
sweet soil ~ alkaline soil (above 7.0 soil pH)
symbiotic relationship ~ mutually-beneficial association of unlike organisms
symplast ~ network of living cells in bark and wood (axial & radial parenchyma)
symptom ~ function is altered (see also sign)
syndrone ~ totality of effects produced in a plant by one disease
synergistic ~ host response to pathogens exceeding the response to individuals
systemic ~ acting throughout the entire organism
taiga ~ northern conifer forest biome; typically composed of spruce, fir & pine
tannin ~ astringent phenol derivation widely distributed by plants
tanning ~ color-altering of chemical reaction wood by pioneer pathogens
taper ~ relative change in branch or stem diameter
tapping ~ intentional tree-wounding to obtain sap or resin (i.e. sugar maple)
tap root ~ dominant, descending root
target ~ life or property potentially affected by tree failure
target canker ~ target-shaped, perennial canker (usually strumella or nectria)
taxonomy ~ systematic classification
TDR ~ transfer of development rights
telephone pole tree ~ single-stemmed tree, without visible root flares
temperate forest ~ regional forest, averaging above 50 degrees (F) 2-4 months
tenants in common ~ individuals holding the same land by several/distinct title
tension wood ~ reaction wood in hardwood root/branch/stem (windward side)
terminal ~ see leader
terminal bud ~ bud on stem apex (synonym apical bud)
terminal bud scale scar ~ visible twig mark; useful in measuring annual growth
terracing ~ method of lowing grade in stages
territory ~ wildlife-defended area
test tube ~ slender glass/plastic tube; closed at one end (scientific testing)
thinning ~ see crown thinning
thorax ~ second or middle region of insect body (with six true legs attached)
thorn ~ stout, sharp woody outgrowth of twig, branch or stem
throughfall ~ precipitation that falls through a canopy
through pruning ~ center crown removal, to provide right-away clearance
till ~ intentional soil surface disturbance for cultivation (synonym plow)
timber ~ forest crop, other than fuelwood
timberline ~ see tree line
tissue ~ group of cells of similar structure and function
tissue analysis ~ analysis of leaf tissue for micro and macroelements
tissue culture ~ cultivation of cells/tissue/organs in a sterile synthetic medium
tissue testing ~ see tissue analysis
tolerant ~ capable of sustaining disease without serious damage
topiary ~ shearing a tree or shrub into a desired shape (more than once a year)
topping ~ destructive, tree height reduction, indiscriminate to nodes/laterals
topsoil ~ surface soil layer which is disturbed during cultivation
tort ~ wrongful act involving personal injury, for which a civil action may exist
toxicity ~ capacity of a substance to produce an injury
toxic tort ~ act or event in which a contaminant injuries persons or property
tracheid ~ single resin or sap transport cell of gymnosperms (conifers)
tracing ~ see wound scribing
tradeoff ~ when benefits derived from treatment outweigh the injury caused
transcript ~ a written version of verbal statements
translocation ~ movement of foods and wastes within a plant
transmission ~ spread of a pathogen from plant to plant
transpiration ~ leaf surface water loss
transplant ~ relocating nursery stock
transplant shock ~ stress following transplant
transport ~ dynamic or absorptive transfer of food and elements through plants
treble damages ~ damages given by statute, found by jury & tripled in amount
tree ~ large, woody perennial, with well-defined stem, height rarely under 15 ft
tree injection ~ see stem injection
tree island ~ lowering soil grade around an isolated tree or group of trees
tree lawn ~ reserved space between curb and sidewalk for planting trees
tree line ~ limit of tree growth (altitude, latitude, aridity, flooding & pollution)
tree log ~ see dendrocronology
tree peninsula ~ lowering soil grade around a narrow woodland strip
tree preservation ~ tree protection before, during & after construction
tree protection zone ~ only arborist-supervised soil disturbances allowed
tree spade ~ gas/diesel-powered machine that digs up and moves trees
tree stand ~ see stand
tree stand delineation ~ general accounting of existing vegetation
tree well ~ natural tree grade preserved from soil fill with retaining wall
tree wrap ~ protective sheath on newly-installed trees (not recommended)
trenching ~ open excavation for utility installation
trespass ~ unlawful interference with the property or rights of another
trier of fact ~ judge, jury or panel which determines the issues of controversy
tropical forest ~ regional forest, averaging 65+ degrees (F) the coldest month
tropism ~ plant response to external stimulus
truncated soil ~ upper soil loss, whether by erosion, grading or excavation
trunk ~ see stem
TSI ~ timber stand improvement (removal or killing of defective trees)
tuber ~ much-thickened, underground stem which bears “eyes” (potato buds)
tundra ~ biome of low artic vegetation; between tree line & perpetual ice/snow
tunneling ~ enclosed excavation for utility installation
turbidity ~ reduction of transparency of a liquid due to suspended particles
twig ~ smallest woody division off a branch; the current year’s growth
twitch trail ~ see skid road
undercut ~ see precut
undergrowth ~ herbaceous cover, lower shrubs & lowest trees, under a canopy
understory ~ all vegetation under an overstory
uniform ~ trees forming an orderly, even canopy
urban forestry ~ art and science of caring for urban forests, woodlands & parks
urban plaza tree ~ tree growing in a mostly paved area
urban tree decline ~ declines initiated by people and their cultural habits
u-shaped discolored streak ~ indicates insects have bored in & back out again
utility ~ entity that delivers a public service (i.e. electricity, telephone & cable)
utility engineer ~ one who designs utilities and develops plans
utility space ~ physical area occupied by utility’s facilities to ensure operation
valuation ~ analysis of monetary value; not constrained by appraisal duties
VAM ~ vesicular-arbuscular mycorrhizae (common of endomycorrhizae)
variation ~ differences in like-species trees, due to genetics/environment
variety ~ distinctive, breeding subdivision of a species
vascular ~ plants having phloem and xylem-conducting elements
vector ~ pathogen-transmitting organism
vegetation ~ see ground cover
venation ~ leaf vein arrangement
ventral ~ of or relating to the belly (the lower surface of an insect)
verdict ~ trial decision by a jury in a criminal or civil case
vertical branch spacing ~ relative branch distance along the stem
vertical mulching ~ filling vertically-drilled soil holes with porous material
vessel ~ vascular, water-conducting wood element
viability ~ state of being alive
vigor ~ genetic capacity to resist stress and strain
viroid ~ smallest known agent of infectious disease
virulence ~ pathogen propagule number required to cause a disease response
virus ~ submicroscopic, disease-producing, intracellular parasite
vista pruning ~ selective crown thinning to improve a view from a vantage point
vitality ~ ability to grow under the condition an organism finds itself in
volunteer top ~ shoot assuming dominance after a tree looses its central leader
v-pruning ~ see through pruning
wanton conduct ~ reckless disregard for the rights and safety of others
waterborne ~ suspended and/or carried by water
water-holding capacity ~ moisture-holding ability of soil
water-insoluble nitrogen ~ non-water-soluble nitrogen fertilizer
watershed ~ region drained by a single stream or drainage network
watershoot ~ see sprout
watersprout ~ see sprout
water table ~ upper level of water-saturated ground
weed ~ wild-growing, competitive, valueless, unwanted small plant
weed tree ~ competitive, valueless, unwanted tree
wetland ~ transitional area between aquatic and terrestrial ecosystems
wetting agent ~ surfactant compound that reduces surface tension of water
wetwood ~ see bacterial wetwood
wing ~ thin, flat, dry, shelflike projection on a fruit or seed or along side a twig
white rot ~ advanced, whitish wood rot (both cellulose & lignin are digested)
whorled ~ leaves arranged in a circle around a point on the stem
wilt ~ leaf-drooping response to water loss
windbreak ~ strip of trees/scrubs maintained to alter windflow/microclimate
windshake ~ see ring or ray shake
windthrow ~ down tree by natural causes (usually uprooted by wind)
windward ~ tree side away from lean
winter drying ~ foliage desiccation due to dry winds & cold-restricted water
wire basket ~ metal rootball cage, used in small plant transplanting
witch’s broom ~ disorderly clump of shoot development
wolf tree ~ spreading tree that over-occupies desired species’ growing space
wood ~ highly-ordered arrangement of cells (with walls of cellulose and lignin)
wood borer ~ destructive wood-boring insect
wound closure ~ process of woundwood closing a tree wound
wound scribing ~ creating smooth wound margins by cutting away loose bark
wound tracing ~ see wound scribing
wood galleries ~ wood borer tunnels (also termites, carpenter ants & worms)
woodland ~ plant community comprised of spreading trees and open areas
woody plant ~ perennial plant, with stem (s) and branches containing lignin
wound ~ sufficient injury to induce compartmentalization response in trees
wound dressing ~ tree wound preservative that protects decay microorganisms
woundwood ~ large, woody (lignified) ribs that close woody plant wounds
xylem ~ principle water-conducting & supporting tissue of higher plants
yeast ~ single-celled fungi (often clumped), commonly grow in exudation
yellows ~ term given to a group of diseases caused by mycoplasmas
zone line ~ boundary of different species of deadwood-inhabiting organisms
zoning ~ basic means of land use regulation by dividing a community into zones

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