Glossary of Terms – Indiana Accredited Horticulturist Program

Glossary of Terms

  • Abiotic Disease – abnormal condition of a plant that is caused by a non- infectious agent, i.e.; environment, people
  • Abscission – natural dropping of leaves, flowers and other plant parts.
  • Acid Soil – soils with a pH below 7.0.
  • Active Ingredient – the chemical that actually controls the pest.
  • Aeration – increasing the amount of air space in the soil by tilling or removing cores.
  • Aggregation – combining soil particles
  • Alkaline Soil – soil with a pH above 7.0.
  • Alternate leaf – the arrangement of leaves or buds when they occur singly at a node.
  • Annual – a plant that completes its life cycle, from seed to seed in one year.
  • Annual Ring – the annual growth layer when observed in cross section, the result of water transporting tissues becoming inactive.
  • Apical Dominance – the suppression of lateral bud growth by the terminal bud.
  • Backfill – a soil mixture that balances sand loam, clay and organic matter to obtain a medium with adequate air space for drainage and root growth.
  • Bacteria – one cell microorganisms that multiply by division and cause produce blights, wilts, or leaf spots.
  • Balled and Burlapped [ B & B stock] – trees and shrubs that have been prepared for transplanting by digging with soil around the roots in an undisturbed ball then covered with burlap or similar mesh fabric.
  • Balled and Potted [B & P] – trees and shrubs that have been dug with soil around the roots and placed in a container.
  • Bare-root Stock [B R] – harvested trees and shrubs that have been dug and the soil or growing medium removed from around the roots.
  • Benchmark – a point of defined elevation on a grading plan
  • Biennial – a plant that completes its life cycle in 2 years.
  • Binomial System – a system in which a plant is named with a two part scientific name.
  • Biotic Disease – abnormal condition of a plant caused by a living micro-organism.
  • Branch Collar – enlarged base of the limb that produces the tissue to close a pruning cut.
  • Bud – a young undeveloped shoot or flower.
  • Budding – a propagation method that involves the placement of a bud from the desirable plant on the rootstock of a seedling.
  • Calcium – a nutrient necessary for plant growth, also used to raise pH.
  • Caliper – diameter of a tree measured at 6” above the ground for trees less than 4 inches in diameter. For larger trees, the caliper measurement is taken at 12” above the ground.
  • Candle – the new shoot of growth on a conifer, i.e.; pine and spruce trees
  • Cation Exchange Capacity – measure of soils capacity to hold nutrients
  • Callus Tissue – wound tissue that forms on or below a wounded surface.
  • Cambium – a one or two cell thick zone of cell division that produces phloem and xylem.
  • Cell – the basic microscopic building block of living organisms where growth processes occur.
  • Cell Division – the basis of plant growth which occurs in the meristem.
  • Chlorophyll – the green pigment necessary for photosynthesis.
  • Chlorosis – yellowing of foliage due to the loss or breakdown of chlorophyll.
  • Clay – smallest of the soil particles that combine with silt and sand to determine the soil texture
  • Clone – a group of individuals that have originated from a common plant. Propagation of a clone cannot occur from seed but instead from cuttings, grafts or divisions.
  • Cold Hardiness – minimum cold temperature at which twigs and buds of a plant will survive.
  • Compound Leaf – a leaf divided into two or more parts called leaflets.
  • Contract Documents – plans and specifications and other legally binding documents that define how a project is to be completed.
  • Cool Season grasses – lawn grass species that prefer cooler temperatures and may go dormant when temperatures are above 90 degrees.
  • Conifer – woody trees and shrubs that produce cones, includes pines, spruce, hemlock, juniper, and spruce.
  • Container grown – plants grown continuously in a container, usually in artificial media.
  • Cultivar – a cultivated variety
  • Cuttings – a part of a plant used to develop a new plant with roots, stems and leaves.
  • Dead-heading – removing spent flowers to encourage continued blooming or to improve appearance of a plant.
  • Deciduous – trees or shrubs that drop their leaves at the end of each growing season.
  • Defoliate – loss of plant leaves that is often caused by insects, diseases or environmental conditions.
  • Dermal Absorption – most common method of pesticide exposure to the applicator through the skin or eyes
  • Desiccation – Dehydration or loss of water from the plant tissue.
  • Disease Triangle – Disease management concept that recognizes the need for a host, a pathogen and the correct environment to result in a disease. .
  • Landscape Design – the art of creating a functional and aesthetically pleasing outdoor environment for human use.
  • Design principles – order, unity, dominance, repetition, scale and balance
  • Dicotyledon – a flowering plant so named because it has two cotyledons or seed leaves.
  • Division – a method of propagating plants by breaking the roots or bulbs of the parent plant apart.
  • Dormancy – an inactive period during which a seed or plant rests due to internal causes.
  • Double cut method – A pruning technique used to prevent splitting the tree bark.
  • Elevation – the vertical form of the land surface on a landscape site.
  • Elevation View – a two dimensional drawing that shows a side view of a project.
  • Evergreen – A plant that retains all or most of its foliage year round.
  • Exotic Plants – plants that have been introduced into region or state.
  • Family – a grouping of genera that resemble each other, the family name ends in –aceae.
  • Fertilizer – a material added to soil to provide elements essential for plant growth.
  • Fertilizer analysis – the percent of nitrogen, phosphorous (P2O5) and potassium (K2O) in a fertilizer.
  • Fertilizer, complete – a fertilizer that contains nitrogen, phosphorus and potassium.
  • Fertilizer, incomplete – a fertilizer that contains any combination of nitrogen, phosphorus and potassium, but not all three.
  • Fertilizer, inorganic – fertilizer produced thru mining or manufacturing
  • Fertilizer, organic – fertilizer product that is a by-product of plant or animal residues and usually is slowly available to the plant.
  • Flower – showy part of the plant that produces fruit and seeds.
  • Flushes of growth – growth that originates from the enlargement of a specific number of cells contained within the bud.
  • Fruit – the mature ovary from a flower that functions to protect the developing seeds. An important criterion in the selection of a plant for use in a landscape.
  • Fungi – microscopic thread-like plants that produce spores. Rusts, molds, leaf spots, mushrooms and cankers are produced by fungi.
  • Fungicide – a pesticide that kills or inhibits the growth of fungi.
  • Genus – a group of closely related species.
  • Girdling – the severing or removal of bark on a woody stem.
  • Girdling roots – condition where roots grow around the trunk of a tree and restrict the movement of water, nutrients and food reserves.
  • Grading Plan – a drawing showing the topography, and the location of proposed elements and proposed elevations for a site.
  • Grafting – the process used to join a root stock to a branch or scion to produce a better plant.
  • Hardening Off – the gradual adjustment that plants go through to withstand extreme condition such as colder temperatures.
  • Hardy Bulb – a perennial that forms an enlarged underground structure.
  • Heading back – pruning technique that reduces the stem length to reduce the overall size of a plant.
  • Herbaceous – plants with non-woody fleshy stems.
  • Herbicide – a pesticide used to kill or inhibit plant growth, normally used on weeds.
  • Horizon – layers of soil in an undisturbed site.
  • Hybrid plant – a plant that is the produced by pollenizing the pistil of one species with the pollen of another. Written with an “x” in the scientific name.
  • Inert ingredient – material that the active chemical ingredient is dissolved into.
  • Insecticide – a pesticide used to control insects.
  • Ion – positively or negatively charged particles.
  • Iron [Fe] – a micronutrient needed during photosynthesis.
  • Iron chlorosis – a condition where iron is deficient in the leaf resulting in leaf yellowing with green veins.
  • Internode – the part of a stem located between nodes
  • Juvenility – stage in plant development where growth is in the vegetative mode only and will not produce seeds.
  • Layout Plan – A drawing showing the exact location of proposed site elements. Lateral Bud – a bud at the base of a leaf.
  • Layering – a simple method of propagation by developing roots on the stem of a plant.
  • Leaching – downward movement of water and minerals in the soil.
  • Leaf scorch – a symptom of lack of water in a leaf.
  • Machine Balled – nursery plant that is dug bare root and packaged in sawdust or sphagnum peat moss and wrapped in plastic.
  • Macronutrients – nine elements essential to plant growth and development used in large quantities (carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium).
  • Magnesium [Mg] – nutrient that aids in the development of green color (chlorophyll) in the plant tissue.
  • Maturity – the stage in plant growth at which seeds may be produced.
  • Meristem – tissue in all plants consisting of undifferentiated cells.
  • Metabolism – activity in the cell that includes all the chemistry of life.
  • Microclimate – the environment immediately surrounding a plant or area of a landscape site.
  • Micronutrients – eight elements essential to plant growth and used in small quantities (iron, copper, manganese, zinc, molybdenum, boron, chlorine and nickel).
  • Miticide – a pesticide used to control mites
  • Monocotyledon – a flowering plant with one cotyledon or seed leaf.
  • Mulch – A layer of organic or inorganic material used around plants to moderate soil temperature, conserve moisture and reduce weeds and run-off.
  • Native Plant – plants grown in natural populations in a region or state.
  • Nematocide – chemical used to kill nematodes.
  • Nematode – a microscopic work capable of piercing roots and feeding on them.
  • Nitrogen – nutrient responsible for vegetative growth that becomes part of the protein molecule.
  • Node – area on a stem where leaves are attached and buds formed.
  • Non Selective Herbicide – pesticide which will kill all vegetation it comes in contact with.
  • Non-translocated herbicide – weed killer that does not move when absorbed into the plant.
  • Nutrients – elements necessary for plant growth.
  • Nutrient Deficiency – lack of adequate amount of a plant nutrient or soil conditions that prevent the plant from taking up the nutrient.
  • Opposite leaf – the arrangement of leaves or buds when they occur in pairs at the nodes.
  • Oral Exposure – method of pesticide exposure to the applicator by ingestion through the mouth.
  • Organ – plant parts composed of multiple tissues organized for specific function; leaves, stems, buds roots.
  • Organic matter – partially decomposed plant and animal residue.
  • Ornamental grasses – perennial or annual with grass like habit that is not mowed like turf.
  • Pathogen – A living micro-organism capable of producing a plant disease. ie; fungi, bacteria, viruses and nematodes.
  • People Pressure Diseases – abnormal conditions in plants caused by the ignorance and abuse of people.
  • Perennial – a plant that lives from one season to the next and usually lives for more than 2 years.
  • pH – a measure of a soils hydrogen ion activity on a scale from 0 – 14 that indicates the acid or alkaline condition of the soil. A pH of 7 is neutral.
  • Phloem – the tissue responsible for transporting “plant food” in the plant.
  • Photosynthesis – a metabolic system which produces sugar and oxygen from carbon dioxide, water and light energy.
  • Phytotoxicity – plant injury caused by sensitivity to a pesticide.
  • Phosphorus – nutrient used during early growth and for root development and flower and seed production.
  • Plant tissue – organized groups of large numbers of cells to accomplish a particular function.
  • Planting Plan – a scale drawing showing the location of all plants to be installed on a project.
  • Post-emergent – application of a herbicide after the plant leaf emerges above the soil surface.
  • Potassium [K] – nutrient used by a plant to build a resistance to cold, also used in food or nutrient transport within the plant.
  • Personal Protective Equipment [PPE] – Clothing and equipment necessary to avoid overexposure to pesticides.
  • Pre-emergence – application of a herbicide before the plant leaf emerges from the soil.
  • Potted Plants – nursery stock dug bare root and then planted in a container.
  • Propagation – methods of reproducing plants ie: seeds, cuttings, grafting, budding, division, bulbs.
  • Quarantine – the restriction of movement of plant materials in order to control the spread of a disease or insect.
  • Reentry Statement – details the time interval between application of a pesticide and the entry of an unprotected person into the application site.
  • Rejuvenation – pruning process where the plant is cut back to the ground.
  • Renewal – pruning process used to remove older growth over a 3 year period.
  • Respiration – plant process where stored energy is released to support plant growth.
  • Respiratory exposure – method of pesticide exposure to the applicator through the lungs.
  • Rhizome – underground plant stem that can send out roots at the nodes
  • Root-bound –The root system of a container plant becoming overgrown and circling repeatedly inside the container. Also called pot bound.
  • Root flare – the transition zone between the trunk of a tree and the root system, also called root collar. Should be exposed at the soil surface when planting the tree.
  • Root hair – outgrowths from the cells on the surface of the root, located within one half inch of the root tip.
  • Root pruning – cutting roots to encourage a more compact root system and improve transplanting success.
  • Sand – largest of the individual soil particles
  • Scientific name – a two part name used to identify plants and animals; it consists of the genus and species names. Developed by Carolus Linneaus.
  • Section View – a two dimensional drawing that shows a cut-through side view of a project.
  • Selective herbicide – Pesticide which will control a specific type of weed with little or no damage to other plants.
  • Senescence – stage of plant development where the plant prepares for death of a plant organ.
  • Silt – intermediate sized soil particles
  • Simple Leaf – an undivided leaf blade
  • Slow release fertilizer – fertilizer product which provides nutrient release over an extended period of time.
  • Soil Amendments – materials added to soil to improve texture, aeration, water retention and nutrient retention. Usually organic matter.
  • Soil texture – combination of sand, silt and clay particles.
  • Spot Elevation – an individual point on a project site that is called out on the drawing for its precise elevation.
  • Species – a group of closely related plants, each possessing similar characteristics.
  • Starter fertilizer – a fertilizer applied when planting or seeding containing nutrients to aid root and seedling growth.
  • Stolon – above ground plant stem that can develop new plants at the nodes.
  • Stomates –small plant structures on the underside of the leaf that permit the exchange of gases and water vapor from the leaf to the atmosphere.
  • Sulfur [S] – a macronutrient needed by plants, also a compound used to lower pH.
  • Thatch – dead and decomposing grass plants
  • Thinning – pruning technique where an entire branch is removed.
  • Tissue – a group of cells with a similar function.
  • Tissue Culture – A specialized method of propagation utilizing small amounts of tissue from the parent plant.
  • Translocation – movement of materials around in a plant.
  • Translocated herbicide –a chemical that moves in the plant once it is absorbed by the leaf or roots.
  • Transpiration – evaporation of water from the leaves through the stomates to the atmosphere.
  • Toxicity – inherent ability of a chemical to cause harm to a living entity
  • Tuber – a modified plant structure to store plant food.
  • Turgid – leaves not wilted; having adequate moisture.
  • Variety – a subdivision describing a race or form within a species.
  • Vegetative Propagation – plant reproduction without seed. ie; cuttings, grafting, bulbs, division, budding.
  • Virus – disease causing agent, smaller than bacteria causing leaf spots or yellows in plants.
  • Water sprout – a fast growing shoot that originates from a bark wound of pruning cut.
  • Warm Season Grasses – turf grasses that grow well when temperatures are above 90 degrees and go dormant in the winter.
  • Wilting – plant tissue that becomes limp due to a lack of water.
  • Xylem – tissue responsible for water and nutrient transport in plants.
  • Zone – USDA Hardiness zone describing plants ability to withstand cold temperatures.

NOTE: Chapter 8 includes an extensive glossary of terminology for insects.


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Page last modified: October 31, 2023

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