Abiotic - The non-living components of the environment, such as air, rocks, minerals, water, coal, peat, plant litter, etc.

Absorption - The process by which a solution passes from one system to another, e.g., a herbicide passes from the soil solution into a plant root cell or from the leaf surface into the leaf cells.

Achene - Small, dry, one-seeded fruit.

Acid soil - A soil having a preponderance of hydrogen ions (low pH) over hydroxyl ions (high pH) in the soil solution; thus a soil with a pH below the neutral range (pH 6.6 to 7.3).

Acre - An area of land containing 43,560 square feet, roughly the size of a football field, or a square that is 208 feet on a side.

Active ingredient (ai) - The chemical in a herbicide formulation primarily responsible for its phytotoxicity and which is identified as the active ingredient on the product label.

Acuminate - Having a leaf tip whose sides are concave and tapering to an elongated point.

Acute - Leaf shape, having margins tapered to a point.

Adjuvant - Any substance in a herbicide formulation or added to the spray tank to modify herbicidal activity or application characteristics.

Adsorption - The process by which an ion (or charged particle) in a solution bonds to a charged surface, e.g., a herbicide adheres to a soil colloidal surface like clay, or organic matter.

Adventitious bud - A bud which develops at the base of a needle cluster, on a root, or on woody tissue on a branch or leader, when the end of the branch or leader is injured or cut off.

Afforestation - Establishing a forest on an area which has not previously had trees growing on it.

Alkaline - Referring to soil pH of 7.0 and higher, performance of some tree and shrub species is affected in these soils because needed nutrients e.g., iron, become insoluble and unavailable to the plant.

Alkaline soil - Soil having a preponderance of hydroxyl ions (high pH) over hydrogen ions (low pH) in the soil solutions; thus a soil with pH above the neutral range (6.6 to 7.3).

Allelopathy - The adverse effect on the growth of plants or microorganisms caused by the action of chemicals produced by other living or decaying plants.

Alternate - Bud or leaf arrangement (singly) along a stem at spiraled intervals.

Annual ring - The growth layer of one year, as viewed on the cross section of a stem, branch, or root.

Antagonism - An interaction of two or more chemicals such that the effect when combined is less than the predicted effect based on the activity of each chemical applied separately.

Anther - The pollen containing part of a stamen.

Anthracnose - A disease usually characterized by ulcer-like leaf or fruit spots and caused by fungi that produce asexual spores in the type of fruiting body called an acervulus.

Apiculate - Ending abruptly in a short-pointed leaf tip.

Appressed - Lying close and flattened against.

Aquifer - A sand, gravel, or rock formation capable of storing or conveying water below the surface of the land.

Arcuate venation - To arch or curve like the veins in dogwood (Cornus).

Ascending - Rising somewhat obliquely and curving upward.

Astringent - Pungent, strong odor or taste.

Awl-shaped - Oval shaped, with sharp pointed end, e.g., juniper leaves.

Axillary - Pertaining to the area where the leaf petiole and stem are connected or the axil.

Band treatment - Applied to a linear restricted strip on or along crop rows rather than continuously over the field area.

Basal treatment - Applied to encircle the stem of a plant just above the soil surface such that foliage contact is minimal. A term used mostly to describe treatment of woody plants.

Bedrock - Unbroken solid rock, overlain in most places by soil or rock fragments.

Biological control - The use of organisms or viruses to control parasites, weeds, or other pests.

Biosphere - The part of Earth's surface, soil, water and its immediate atmosphere occupied by living organisms.

Bipinnate - Twice pinnate (as in honey-locust leaves).

Blade - The broad, flat, green part of the leaf.

Bole - The main trunk of a tree.

Bract - A modified leaf from the axil of which a flower or flower cluster arises.

Broadcast treatment - Applied as a continuous sheet over the entire field.

Broad-elliptic - Wider than elliptic.

Browse - Portions of woody plants including twigs, shoots, and leaves used as food by such animals as deer.

Browseline - The uppermost limit on trees and tall shrubs to which livestock and big game animals browse. (syn. grazing line.)

Browser - Large mammals that feed on the young growing parts of trees or shrubs.

Buttressed - Broadened base or arched root flare of the trees trunk.

Calcareous soil - Soil containing sufficient free calcium carbonate (lime) or calcium-magnesium carbonate (dolomite) to effervesce visibly when treated with cold 0.1 M HCl in water.

Calyx - Outermost whorl of modified leaves in a flower, usually green, but sometimes showy colored.

Cambium - The layer of cells between the inner bark and wood of a tree where cell division takes place.

Candle - The new bright green and tender shoot growth all conifers produce in the spring.

Canopy - The upper level of a forest, consisting of branches and leaves of taller trees.

Capsule - A fruit structure consisting of two or more chambers.

Catkin - A scaly-bracted spike of unisexual flowers.

Cell - The basic structural unit of all living organisms. An organism may be composed of a single cell (e.g. bacteria) or many cells working together (all "higher" organisms, including man).

Chaffy - Covered with small thin, dry scales.

Chemical name - The systematic name of a chemical compound according to the rules of nomenclature of the International Union of Pure and Applied Chemistry (IUPAC), Chemical Abstracts Service, or other organization.

Chemical tolerance - Ability to continue normal growth or function when exposed to a potentially harmful agent (there is no general agreement as to the distinction between herbicide tolerance and herbicide resistance in plants).

Chlorosis - A leaf symptom due to mineral deficiencies where the leaf will remain green next to the veins and become yellow from the margins inward.

Chlorophyll - The green photosynthetic substance in plants which allows them to capture solar energy.

Ciliate - Fringed with hairs on margin.

Clay - Soil particles less than .002 mm in size.

Clone - A plant group derived from a single individual through vegetative reproduction. Example: A clone of many aspen trees may sprout from the roots of a single aspen tree, after it is cut.

Co-Dominant - A tree receiving full light from above, but comparatively little from the sides. Such trees usually have medium sized crowns.

Community - The populations of species living in a common ecosystem.

Compatibility - The characteristic of a substance, especially a pesticide, of being mixable in a formulation or in the spray tank for application in the same carrier without undesirably altering the characteristics or effects of the individual components.

Competition - The active acquisition of limited resources by an organism which results in a reduced supply and consequently reduced growth of other organisms in a common environment.

Compound - A leaf that is made up of more than one leaf blade, termed leaflets.

Compressed stone - Flattened stone.

Concentration - For herbicides, the quantity of active ingredient or parent compound equivalent expressed as moles or mass per unit volume or per unit mass of the resulting solution or mixture. Expressions of percent should be avoided or used only for expressions of mass per mass.

Conical - Cone-shaped.

Conifer - A tree belonging to the Order Coniferales which is usually evergreen, cone-bearing and with needle, awl or scalelike leaves such as pine, spruce, fir and cedar; often referred to as a "softwood."

Coniferous - Cone bearing trees and shrubs.

Connate - Like parts fused together into one.

Conservation - The protection, improvement, and use of natural resources according to principles that will assure their highest economic and social service.

Contact herbicide - A herbicide that kills primarily by contact with plant tissue rather than as a result of translocation; only the portions of the plant which actually come in contact with the chemical are affected.

Convex - Curved like the outer surface of a sphere.

Coppice - To regrow wholly or mainly from sprouts.

Corymb - Flat-topped or convex flower cluster, outer flowers opening first.

Crenate - Toothed with round, shallow teeth.

Crown - The branches and foliage of a tree, the upper portion of a tree.

Crown classification - Individual trees in a stand may be classified according to the relative size and height of their crowns compared to other trees in the stand. In descending order of crown height and size the classes are: dominate, co-dominate, intermediate, suppressed.

Crown cover - The canopy of green leaves and branches formed by the crowns of all trees in a forest. (syn. leaf canopy.)

Cultivar - A cultivated variety as distinguished from a botanical variety.

Cuneate - Wedge-shaped.

Cyme - Flat-topped flower cluster, central flower opens first.

Damping-off - The killing of young seedlings by certain fungi that cause decay of the basal stem or roots.

Deciduous - Not persistent, leaves falling in autumn.

Decurrent - Spreading branches, lack of central leader.

Defoliation - The loss of leaves or foliage on a plant or tree.

Defoliant - A chemical that causes the leaves to fall from a plant.

Dehiscent - Splitting open along seed capsule or pod to emit individual seeds.

Dentate - Teeth along leaf margins are pointed outward.

Den tree - A hollow tree used as a home by a mammal.

Desiccant - Any substance or mixture of substances used to accelerate the drying of plant tissue.

Dicotyledon (dicot) - A member of the Dicotyledonae; one of two classes of angiosperms usually characterized by the following: two seed leaves (cotyledons), leaves with net venation.

Dieback - The progressive dying, from the tip downward, of twigs, branches or tops.

Dioecious - Male and female flowers on separate plants.

Directed application - Precise application to a specific area or plant organ such as to a row or bed or the leaves or stems of plants.

Dispersible granule (DG) - A dry granular formulation that will separate or disperse to form a suspension when added to water.

Dominate trees - Those trees within a forest stand which extend their crowns above surrounding trees and capture sunlight from above and around the crown.

Doubly serrate - Many large and small serrations along the leaf margin.

Drupe - Fleshy fruit with a pit or stone.

Drupelet - A small drupe.

Ecosystem - An ecological entity consisting of the biotic community and the nonliving environment functioning together in an inseparable interacting system.

Ecotype - A population within a species that has developed a distinct morphological or physiological characteristic (e.g. herbicide or biotic pest resistance) in response to a specific environment and that persists when individuals are moved to a different environment.

Edge - The boundary between open land and woodland or two other ecological communities. This transition area between environments provides valuable wildlife habitat.

Elliptic - Longer than wide with rounded ends, like an ellipse.

Emulsifiable concentrate (EC) - A single phase liquid formulation that forms an emulsion when added to water.

Emulsifier - A substance that promotes the suspension of one liquid in another.

Endocarp - The inner layer of the pericarp of a seed, e.g. stone fruit.

Entire margin - Unbroken, without teeth or lobes.

Environment - The sum total of all biological and physical factors affecting an organism, population, or community.

Epicormic branching - Branches which grow out of the main stem of a tree, arising from buds under the bark. Severe epicormic branching increases knottiness, thereby reducing the quality of lumer sawn.

Epidemic - A temporary widespread outbreak of disease.

Erose - Irregularly toothed or eroded.

Erosion - Detachment and movement of soil or rock by water, wind, ice, or gravity.

Evergreen - Trees which retain green foliage throughout the year. Not all conifers are evergreens. An example is larch, a deciduous conifer.

Excurrent - Tree growth is pyramidal, similar to spruce tree, central leader.

Exfoliate - The natural habit of trees for the bark to peel off in shreds or thin layers.

Fascicle - A small bundle, e.g., 2 to 5 needles per cluster in pines.

Filament - Portion of the stamen comprising the stalk.

Fireblight - Bacterial disease causing leaves of susceptible plants to blacken but remain attached to the twigs. Affects pear, apple, crabapple, cotoneaster and mountain-ash.

Firebreak - A natural or constructed barrier utilized to stop or check fires that may occur or to provide a control line from which to work. Sometimes called a fire lane.

Fissures - Pertains to furrows created in bark as the tree grows.

Flowable (F) - A two-phase formulation containing solid herbicide suspended in liquid and that forms a suspension when added to water.

Foliage - Growth of leaves on a tree or other plant.

Follicle - A dry, dehiscent fruit developed from a simple ovary and splitting along one suture.

Forb - Any herbaceous plant other than grass on a prairie site.

Fork - A defect characterized by division of the main stem or bole of a tree into two or more stems.

Frill treatment - Placement of a herbicide into a series of overlapping ax cuts made through the bark in a ring around the trunk of a tree.

Frost crack - A vertical split in the wood of a tree, generally near the base of the bole, from internal stresses and low temperatures.

Furrowed - Having longitudinal grooves or fissures.

Gall - A pronounced swelling or outgrowth on a plant.

Girdling - To encircle the stem of a living tree with cuts that completely sever bark and cambium.

Glabrescent - Becoming hairless at maturity.

Glabrate - Nearly glabrous or becoming glabrous with age.

Glabrous - Without hair, smooth.

Glandular - Small, usually shiny bumps on the surface.

Glaucescent - Slightly glaucous.

Glaucous - Covered with a waxy bloom or whitish material that rubs off readily.

Globose - Spherical.

Granular (G) - A dry formulation consisting of discrete particles generally <10 cubic mm and designed to be applied without a liquid carrier.

Growth rate - With reference to wood, the rate at which the wood substance has been added to the tree at any particular point; usually expressed in terms of number of rings per inch. Growth rate bears an inverse relationship to number of rings per inch. Also applies to volume, value, or other types of increase in trees or stands.

Growth rings - The layers of wood laid down each growing season, also called annual rings. These rings frequently are visible when a tree is cut and may be used to estimate the age of the tree, as well as to determine the rate of its growth.

Hardwood - A term used to describe broadleaf, usually deciduous, trees such as oaks, maples, ashes, elms, etc. It does not necessarily refer to the hardness of the wood.

Heartwood - The inner core of a woody stem, wholly composed of nonliving cells and usually differentiated from the outer enveloping layer (sapwood) by its darker color.

Heel-in - To store young trees prior to planting by placing them in a trench and covering the roots or rooting portions with soil.

Herbaceous - Lacking a persistent stem above ground dying back in fall.

Herbaceous vegetation - The low-growing, non-woody plants in a forest understory, including wildflowers and ferns.

Herbicide - A chemical which kills herbaceous (non-woody) plants. In common usage, however, often used interchangeably with the words phytocide (plant killer) and silvicide (tree killer).

Herbicide resistance - The trait or quality of a population of plants within a species or plant cells in tissue cultures of having a tolerance for a particular herbicide that is substantially greater than the average for the species and that has developed because of selection for naturally occurring tolerance by exposure to the herbicide through several reproductive cycles.

Hispid - Covered with bristly hairs.

Horizon, soil - A layer of soil approximately parallel to the land surface with more or less well-defined characteristics that have been produced through the operation of soil forming processes. 1) A-Horizon: the upper horizon of the mineral soil, which features an accumulation of humified organic matter intimately associated with the mineral fraction. 2) E-Horizon: a light-colored horizon of maximum leaching. 3) B-Horizon: the horizon of accumulation to which materials such as clay, carbonates or iron oxides have been added by percolating waters. 4) C-Horizon: the weathered soil parent material.

Humus layer - The top portion of the soil which owes its characteristic features to its content of humus. The humus may be incorporated or unincorporated in the mineral soil.

Hybrid - A sexually produced cross between two closely related species.

Imbricate - Overlapping, like shingles on a roof.

Imperfect (flower type) - Lacking stamens or pistils, but not both.

Impressed - Bent inward, furrowed as if by pressure.

Inconspicuous - Small, not readily noticed by the naked eye.

Incorporate - To mix or blend a herbicide into the soil.

Incurved - Curved inward.

Infiltration - The downward entry of water into the soil. This is distinct from percolation, which is movement of water through soil layers or material.

Insecticide - Any chemical used to destroy insects and other small invertebrates.

Insipid - Lacking taste, smell or quality; dull.

Internode - Part of stem between two nodes.

Interplant - To set young trees among existing forest growth of similar age and/or size, planted or natural, to bring the stand to a fully stocked condition.

Intolerance - The characteristic of certain tree species which does not permit them to survive in the shade of other trees, e.g. aspen and Norway pine are intolerant; sugar maple and balsam fir are tolerant.

Invert emulsion - The suspension of minute water droplets in a continuous oil phase.

Lanceolate - Lance shaped, broadest at base of leaf blade. Much longer than broad, tapers to the leaf tip.

Lateral buds - Those buds below the terminal buds where side branches arise.

Layby application - Applied and incorporated with or applied after the last cultivation of a crop.

Layering - A method of propagation in which adventitious roots form on a stem while it is still attached to the parent plant. Occurs naturally with some species.

LD50 - The dose(quantity) of a substance that will be lethal to 50% of the organisms in a specific test situation. It is expressed in weight of the chemical(mg) per unit of body weight (kg) and the toxicant may be fed (oral LD50), applied to the skin (dermal LD50), or administered in the form of vapors (inhalation LD50).

Leaching - Downward movement of a pesticide, fertilizer or other soluble material through the soil as a result of water movement.

Leader - A terminal leader is the uppermost branch or vertical tip of the tree. It eventually becomes the tree stem or trunk.

Leaflet - A single segment of a compound leaf.

Leaf margin - Refers to leaf edge.

Leaf scar - The mark which remains where a leaf falls off a twig.

Leggy - Pertaining to over growth of trees or shrubs where stem growth is lengthened and weak. Devoid of lateral branches.

Lenticel - A breathing pore in young bark, appearing as a light-colored, often lens-shaped, dot, e.g. on birch.

Loam - A soil textural class containing 7 to 27% clay, 28 to 50% silt, and less than 52% sand.

LRA - Land resource area, designation of soil types within the state or regional boundaries.

Machine, planting - Mechanical equipment which opens a hole or furrow and closes it again and firms the soil about a tree seedling which is usually inserted by hand.

Macronutrient - A chemical element necessary in relatively large amounts (usually greater than 500 ppm in the plant) for the growth of plants. These elements consist of C, H, O, Ca, Mg, K, P, S, and N.

Main stem - The portion of a tree between ground level and the division into major branches, usually referred to as the bole.

Malodorous - Bad smelling.

Mast - Nutlike fruits of trees, such as acorns, beech, and chestnuts. Mast is valuable as a source of food for many wildlife species.

Mature tree - A tree that has reached the desired size or age for its intended use. Size or age will vary considerably depending on the species and intended use.

Micro-encapsulated formulation (ME) - Herbicide enclosed in capsules (or beads) of material to control the rate of release of active ingredient and thereby extend the period of activity.

Micronutrient - A chemical element necessary only in extremely small amounts (usually <50 ppm in the plant) for the growth of plants. These elements include B, Cl, Cu, Fe, Mn, Mo, and Zn.

Miticide - A chemical that is used to control or kill mites.

Monocotyledon (monocot) - A member of Monocotyledonae; one of two classes of angiosperms, usually characterized by the following: one seed leaf (cotyledon), leaves with parallel venation, root systems arising adventitiously and usually diffuse (fibrous).

Mortality - Death or destruction of forest trees as a result of competition, disease, insect damage, drought, wind, fire, and other factors.

Mottled - An irregular spotting or alternating color on leaves, stems and other plant parts.

Mucronate - Abruptly terminated by a short, sharp leaf tip.

Mulch - Any material such as straw, wood or bark chips, leaves, plastic film, loose soil, etc., that is spread on the surface of the soil to protect the soil and plant roots from the effects of rain drops, soil crusting, freezing, and evaporation, or to control weeds.

Needle - Elongate, linear, sharp-pointed leaf.

Node - Joint on a stem, represented by point of origin of a leaf or bud.

Nonselective herbicide - An herbicide which will kill or harm all or most plant species.

Non-target species - A species not intentionally affected by a pesticide.

Noxious weed - A plant defined by law as being especially undesirable, troublesome, and difficult to control.

Oblique - Lop-sided, one side of leaf base is larger, wider or more rounded than the other.

Oblong - Two to three times longer than broad.

Obovate - Inversely ovate.

Obovoid - Leaf shape that is inversely egg-shaped or obovate.

Obtuse - Rounded, approaching semi-circular.

Opposite - Buds or leaves growing in pairs but separated by a stem.

Oval - Twice as long as broad, widest at the middle, both ends rounded.

Ovate - Egg shaped in outline, narrower at the tip.

Overstocked - The situation in which trees are so closely spaced that they are competing for resources, resulting in less than full-growth potential for individual trees.

Overstory - The canopy in a stand of trees. In contrast to the understory which is low growing woody or herbaceous vegetation forming a layer beneath the overstory.

Overtop application - A broadcast or banded application applied over the canopy of crops such as by airplane or a raised spray boom of ground equipment.

Overtopped crown class - Trees with crowns entirely below the general level of the crown cover receiving no direct light either from above or from the sides. (syn: suppressed.)

Ovoid - Three dimensional, egg-shaped.

Palatable - Appetizing taste, savory.

Palmate - With three or more lobes, veins or leaflets arising from one point, often five to seven.

Panicles - Loose, irregular compound flower clusters.

Pathogen - A living organism capable of causing disease in a particular species or range of species.

Pectinate - Like a comb, with many or few narrow pinnate divisions.

Peduncle - Primary flower stalk.

Pelleted formulation - A dry formulation consisting of discrete particles usually larger than 10 cubic millimeters and designed to be applied without a liquid carrier.

Pendulous - Hanging down, drooping.

Percolation - The downward movement of water through soil.

Perfect (flower type) - Having both functional stamens and pistils.

Pericarp - Sometimes used to designate a fruit, technically the ovary wall.

Persistent - Hang on through winter or long period of time, e.g. plant parts: fruits, seeds, leaves, etc.

Persistent herbicide - A herbicide that, when applied at the recommended rate, harms susceptible crops planted in normal rotation after harvesting the treated crop, or that interferes with regrowth of native vegetation in non-crop sites for an extended period of time.

Persistence time - The time required for a pesticide to become inert. Arbitrarily assumed to equal four half-lives when measured persistence time is not available.

Pesticides - Chemical compounds or biological agents used for the control of undesirable plants, animals, insects or diseases.

Pesticide interaction - The action or influence of one pesticide upon another and the combined effect of the pesticide(s) on the pest(s) or crop system.

Petiole - The stalk of a leaf.

pH - The measure of the acidity or alkalinity of soil. Descriptive terms commonly associated with certain ranges in pH are: extremely acid <4.5; very strongly acid, 4.5-5.0; strongly acid, 5.1-5.5; moderately acid, 5.6-6.0; slightly acid, 6.1-6.5; neutral, 6.6-7.3; slightly alkaline, 7.4-7.8; moderately alkaline, 7.9-8.4; strongly alkaline, 8.5-9.0; and very strongly alkaline, >9.1.

Phloem - The tissue in higher plants which transports organic nutrients manufactured in the leaves to other portions of the plant.

Phytotoxicity - Injury or death of plants due to exposure to a chemical.

Pilose - Long, soft hairs.

Pinnate - Compound leaf with leaflets on either side of central axis.

Pith - Spongy center of a twig; if it has crosswalls, it is called "chambered."

Plantation - An artificially reforested area established by planting or direct seeding. Contrast with a natural forest stand which is established naturally.

Plant growth regulator (PGR) - A substance used for controlling or modifying plant growth processes without severe phytotoxicity.

Planting bar - A hand tool used in making a slit-hole in which trees are planted.

Plumed - Feathery.

Polygamo-dioecious - Part of flowers are perfect and part are unisexual with male and female flowers on separate plants.

Polygamo-monoecious - Sexual condition in which some perfect and staminate flowers are on the same plant.

Pome - Fleshy fruit with a core, such as a crabapple.

Postemergence (POST) - (1) Applied after emergence of the specified weed or crop. (2) Ability to control established weeds.

Preemergence (PRE) - Applied to the soil before emergence of the specified weed or crop.

Preplant application - Applied before planting or transplanting a crop, either as a foliar application to control existing vegetation or as a soil application.

Preplant incorporated (PPI) - Applied and blended into the soil before seeding or transplanting, usually by tillage.

Pruning - The removal of live or dead branches from standing trees. With forest trees, pruning is generally done along the trunk to remove the side branches (which cause knots in the wood) to produce a higher quality wood (knot-free).

Pubescent - Covered with short, soft hairs.

Racemes - Pedicled flowers along one stem.

Range - The geographic area in which a tree species grows.

Rejuvenation - Restore to healthy vigorous growth, often through weed control, pruning, fertilization, irrigation or treatment for insects and diseases.

Release - To free trees from competition by cutting or otherwise removing or killing nearby vegetation and branches. Usually applied to young stands.

Reproduction - The process by which the forest is replaced or renewed. This may be: Artificial Reproduction (by means of seeding or planting); Natural Reproduction (from natural seeding or sprouting.

Residual herbicide - A herbicide that persists in the soil and injures or kills germinating weed seedlings for a relatively short period of time after application.

Resinous - Sticky with resin.

Resistance - Ability to withstand exposure to a potentially harmful agent without being injured (There is no general agreement as to the distinction between herbicide tolerance and herbicide resistance in plants.)

Restricted-use pesticide - A pesticide which is designated as such by the Environmental Protection Agency because it is felt that it may generally cause, without additional regulatory restrictions, unreasonable adverse effects on the environment, including injury to the applicator. A "restricted-use" pesticide may be used only by, or under the direct supervision of, a certified applicator.

Reticulate - Like a net, netted venation.

Revolute - Stem or leaf rolled lengthwise so as to expose the top side and conceal the bottom side.

Rhombic - With four nearly equal sides, but unequal angles.

Roots - That portion of the tree which is generally underground and which functions in nutrient absorption, anchorage and storage of food and waste products.

Rose hips - Fruit containing the ovary and seeds of the Rosa species.

Rugose - Rough, covered with wrinkles.

Rufous - Reddish brown.

Saline soil - A soil condition in which soluble salts are present in the soil in sufficient quantity to affect the ability of certain plants to absorb water from the soil. Trees and shrubs do best on soils with salinity levels below 2.0 deciSiemens per meter (dS/M) or millimhos per centimeter (mmhos/cm). However, many plants are able to perform satisfactorily on soils with salinty levels between 2 to 8 dS/M. Only a limited number of species survive at salinity levels between 8 and 16 dS/M. No species grow well on soils with salinity exceeding 16dS/M. The following chart quantifies the ranges of salinity:

  Measurement           Range
 less than 2.0       not saline
     2-4        very slightly saline
     4-8           slightly saline
     8-16         moderately saline
     16+           strongly saline 

Samara - Dry, one-seeded fruit with a membranous wing.

Sand - Mineral soil particles .05 to 2.0 mm in size.

Scale - Bud covering or tiny, blunt leaf.

Scalping - Removing a patch or strip of sod in preparation for planting trees.

Schizocarp - Winged, paired samara-like fruits, e.g. maples.

Scurfy - Scaly or flaky on the surface.

Sediment - Solid material that is in suspension, or transport, or that has been moved from its original location by wind, water, gravity, or ice.

Seepage - Percolation of water through the soil from unlined canals, ditches, laterals, watercourses, or water storage facilities.

Selective herbicide - A chemical which is effective only against certain species and is able to control unwanted plants without serious injury to desirable species.

Senescence - Refers to old age, decline in older trees.

Serrate - Fine, sharp teeth that point upward or forward along the leaf margin.

Serrulate - Finely saw-toothed leaf margin.

Setose - Leaf margins are covered with bristles.

Sessile - With no stalk or petiole.

Shade tolerance - Relative ability of a tree species to reproduce and grow under shade. Tree species are usually classified in descending order of shade tolerance as: very tolerant, tolerant, intermediate, intolerant, and very intolerant.

Shearing - The operation of cutting off trees and brush at ground level by pushing a bulldozer blade along the frozen surface in winter. The stems and trunks are sheared off at ground level.

Shelterbelt - A multi-row wind barrier of living trees and shrubs maintained for the purpose of protecting farmsteads and agroforestry crops by providing wind protection, reduction in energy costs, snow control and aesthetic values.

Showy - Attractive, pertaining to aesthetic value.

Shrub - A low-growing perennial plant with persistent woody stems and low branching habit.

Silt - Mineral soil particles .002 to .05 mm in size.

Sinus - The space between lobes.

Site - An area evaluated as to its capacity to produce a particular forest or other vegetation based on the combination of biological, climatic and soil factors present.

Site preparation - Treatment of a site with mechanical clearing, burning, or herbicides, to prepare a site for planting.

Slash - Debris left after logging, pruning, thinning, or brush cutting; also, large accumulation of debris after wind or fire. It includes logs, chunks, bark, branches, stumps and broken understory trees or brush.

Slash disposal - Treatment of slash to reduce the fire hazard or for other purposes.

Slope - A term of measurement in percent indicating the increase in height over the distance measured. An increase of one foot over a distance of five feet is expressed as a 20 percent slope.

Snag - A standing dead tree used by many species of birds and mammals for feeding and nesting.

Sodic soil - A soil with a pH of >8.5 that contains sufficient sodium to adversely affect crop production and soil structure. The soil structure has been altered through the dispersion of organic matter and clay particles resulting in a dense layer restrictive to moisture and root growth. The shallow root zone above the sodic layer predisposes plants to drought stress. Sodic soils may be found associated with saline conditions.

Softwood - Generally, one of the botanical groups of trees that in most cases have needle or scale-like leaves; the conifers; also, the wood produced by such trees.

Soil - (1) The unconsolidated mineral material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. (2) The unconsolidated mineral matter on the surface of the earth that has been subjected to and influenced by genetic and environmental factors of: parent material, climate (including moisture and temperature effects), macro- and microorganisms, and topography, all acting over a period of time and producing a product (soil) that differs from the material from which it is derived in many physical, chemical, biological and morphological properties, and characteristics.

Soil amendment - Any substance added to the soil that alters physical, chemical, or biological properties, e.g. gypsum, lime, fertilizers, sawdust, etc.

Soil reaction (see pH)

Soil texture - The relative proportion of sand, silt, and clay in the soil.

Soluble concentrate (SC) - A liquid formulation that forms a solution when added to water.

Soluble granule (SG) - A dry granular formulation that forms a solution when added to water.

Soluble powder (SP) - A dry formulation that forms a solution when added to water.

Species composition - The mix of tree species occurring together in the same stand.

Spot treatment - A herbicide applied to restricted area(s) of a whole unit; i.e., treatment of spots or patches of weeds within a larger field.

Spray drift - Movement of airborne spray from the intended area of application.

Sprout - A tree that grows from the stump or root sucker of a parent tree, not of seed origin. Basswood is frequently of sprout origin.

Spur - A saclike or tubular projection on sepal or petal, or a very short fruiting branchlet on apple, pear, or other woody plants.

Stalked bud - Bud whose outer scales are attached to a stalk above the base of the bud axis.

Stamen - Male organ in the flower, pollen bearing.

Stem - The portion of a tree that supports the branches; also called the bole.

Stockade - To fortify or surround.

Stoloniferous - Producing runners that root above the ground surface.

Stomata - Minute openings on the surfaces of leaves and stems through which gases (e.g., oxygen, carbon dioxide, water vapor) and some dissolved materials pass into and out of plants.

Stomatiferous - Many pores on the epidermis of a leaf and appearing as many white dots or nodes.

Stone - A hard, one-seeded endocarp of a drupe.

Striate - With fine longitudinal lines or ridges.

Strobili - Inflorescence marked by scales as in a cone.

Subcordate - Nearly heart-shaped.

Subglobose - Somewhat or nearly round.

Subopposite - A bud/leaf arrangement in which they are close to being opposite from each other, but one is slightly lower than the other.

Subsessile - Nearly stalkless.

Subshrub - A woody or somewhat woody, perennial, winter-hardy plant. The stems of which annually die back partially or wholly to ground level. Resprouts every spring.

Sucker (suckering) - A shoot arising from a root or lower part of the stem of a plant.

Sucker - Synonymous with sprout.

Sunscald - A type of winter injury in which the bark on the southwest side of a stem, branch, or trunk is killed.

Suppressed (see Overtopped, Crown classification) - The condition of a tree characterized by low growth rate and low vigor due to competition with overtopping trees.

Susceptibility - The sensitivity to or degree to which a plant is injured by a herbicide treatment.

Synergism - An interaction of two or more factors such that the effect when combined is greater than the predicted effect based on the response to the factors applied separately.

Taproot - A deep centralized rooting habit of certain tree and shrub species, e.g., oak species.

Terminal bud - Bud at the tip or distal end.

Ternate - Parts occur in threes.

Texture - A somewhat subjective analysis of the tree's appearance from a distance including such characteristics as leaf size, branch angles, branch spacing, symmetry of form, e.g. bur oak is considered coarse while false indigo is considered fine. Deciduous trees may have a fine or medium texture in summer, whereas in winter the bare branches may have a coarser texture.

Thinning - Removal of trees in an overstocked stand to give the remaining trees adequate room for growth.

Tolerance - The capacity of a tree to develop and grow in the shade of and in competition with other trees. Trees able to grow in full or partial shade are considered "tolerant".

Tomentose - Densely woolly, soft hairs and matted.

Trade name - A trademark or other designation by which a commercial product is identified.

Translocated herbicide - A herbicide that is moved within the plant. Translocated herbicides may be either phloem mobile or xylem mobile. However, the term frequently is used in a more restrictive sense to refer to herbicides that are applied to the foliage and move downward through the phloem to underground parts.

Transplant - A tree which has been removed from its original seedbed and replanted one or more times in a nursery.

Tree - A woody plant having a well-defined stem, more or less definitely formed crown and usually attaining a height of at least 10 feet.

Trifoliate - Three leaflets per leaf.

Trilobed - Three lobed, e.g. leaves or fruit.

Trunk - Main stem or bole of a tree.

Truncate - Shape of leaf base that attaches to the petiole, ends abruptly, as if cut off.

Tuberculate - Bearing tubers, a short, thickened organ.

Two-ranked - Appearing to come from only two sides of the twig; not equally distributed around the twig, e.g., elm.

Umbel - Flower cluster with peduncles springing from same point.

Underplant - To set out young trees or sow seed under an existing stand.

Understocked - A stand of trees so widely spaced that, even with full growth potential realized, crown closure will not occur. Understocking indicates a waste of resources, as the site is not fully occupied.

Understory - The lesser vegetation (shrubs, seedlings, saplings, small trees) within a forest stand which forms a layer between the overstory and the herbaceous plants of the forest floor.

Valvate - Edges coming together without overlapping.

Vapor drift - The movement of pesticides as vapor from the area of application after the spray droplets have impinged on the target.

Venation - Pertaining to the vein pattern in the leaf blades.

Water table - The highest point in a soil profile where water continually saturates the soil on a seasonal or permanent basis.

Weed - An unwanted plant.

Well stocked - The situation in which a forest stand contains trees spaced widely enough to prevent competition yet closely enough to utilize the entire site.

Wettable powder (WP) - A finely divided dry formulation that can be readily suspended in water.

Wetting agent - (1) A substance that serves to reduce the interfacial tensions and causes spray solutions or suspensions to make better contact with treated surfaces. (2) A substance in a wettable powder formulation that causes it to wet readily when added to water.

Whorl - A group of three or more leaves at a node, e.g. catalpa.

Wildlife habitat - The native environment of an animal, ideally providing all elements required for life and growth: food, water, cover and space.

Wildlife species - Creatures that are associated with plants, such as insects, mammals and birds.

Wildlife value - A rating value of woody plants to wildlife species.

Windbreak - One or more wind barrier rows of living trees and shrubs maintained for the purpose of protecting crops, feedlots, roadways, farmsteads, gardens, orchards, etc.

Windbreak suitability groups - A guide for selecting the species best suited for different types of soils and for predicting height growth and performance effectiveness.

Woody plants - Plants which live longer than two years and have a thick, tough stem or trunk covered with a layer of cork.

Xylem - The tissue in higher plants which transports water, dissolved salts, and other materials (e.g., pesticides) from the roots to aerial portions of the plant.

Reference Materials