Abdomen – the posterior section of the arthropod body.
Abiotic – nonliving.
Abscission -the controlled shedding of a part, such as a leaf, fruit, or flower, by a plant
Acclimate – to adapt to new environmental conditions.
Acidity – quality of being sour; degree of sourness; having a pH of less than 7.
Adventitious – plant parts, such as shoots and roots, produced in an unusual position on a plant or at an unusual time of development.
Aeration – to be exposed to air; to cause air to circulate through a medium.
Aggregates – (soil); clumps or cemented units of mineral and organic matter.
Algae – aquatic plants that lack a vascular system. Some are microscopic and others are large. Examples are pond scum, kelp and red tides.
Alkalinity – having a pH greater than 7.
Allelopathy – a biological phenomenon that is characteristic of some plants, algae, bacteria, coral and fungi by which they produce certain biochemicals that influence the growth and development of other organisms. The biochemicals, called allelochemicals can have a beneficial or detrimental effect on neighbouring organisms.
Alternate host – a secondary host that becomes infected and is necessary for alternating generations of a disease-causing organism.
Amendment – an alteration or addition to soil to correct a problem.
Anaerobic – able to live and grow where there is no air.
Annual – plants that complete their life cycle in a year or less.
Anther – the upper part of the stamen where the pollen is produced.
Anthracnose – A fungal disease of plants, usually made worse by very wet conditions like a very rainy springtime. It can cause a range of damage from spots on foliage to complete defoliation. If the plant is heavily affected, be sure it has adequate nutrients to help it renew the leaves it has lost. Rake all debris from the plant and dispose of it to prevent re-infection.
Apical bud – a bud at the apex or terminal position on a plant or branch.
Arboretum – pl. arboreta; a place where trees, shrubs, vines and herbaceous plants are cultivated for scientific and educational purposes.
Arthropod – invertebrate animals (insects, arachnids and crustaceans) that have a jointed body and limbs and usually a hard shell or exoskeleton that is molted periodically.
Asexual propagation – the duplication of a plant from a cell, tissue or organ of the plant.
Bacteria – microscopic organisms having round, rod-like, spiral or filamentous single-celled or noncellular bodies often gathered into colonies.
Bacillus thuringiensis – a bacterium used in genetically altered form in the biological control of budworms, gypsy moth larvae, Japanese beetles, and other insect pests. The abbreviation for it is B.t.
Band fertilize – to apply fertilizer in a narrow line along a row of plants or in a circle around individual plants.
Bare root – a plant that is sold or shipped dormant with no soil surrounding its roots.
Basal bud – A bump of growth tissue that forms in the crown of a plant.
Basal foliage – The leaves that grow around the crown of a plant.
Beneficial insects – insects that prey on or parasitize pests.
Bentgrass – a high-maintenance grass used on putting greens. It requires frequent cutting with a reel mower, frequent fertilization and watering. It is highly susceptible to several diseases.
Biennial – plants that complete their life cycle in two years or growing seasons.
Binomial nomenclature – a system in which the scientific name of a plant consists of two parts indicating the genus and species.
Biological control – the use of living organisms or their products to control pest populations.
Biological diversity – presence of many different types of living organisms.
Bolt – the tendency of cool-season plants to grow rapidly and produce seeds when exposed to warm temperatures.
Bonsai – a potted plant dwarfed by special cultural practices.
Botrytis – A necrotic fungus made worse by humid or wet conditions. It is particularly a problem on grapes, strawberries and bulbs, but can occur on many plants. Any steps which improve air circulation and the drying of the foliage, such as thinning and elevating the plant above the surrounding soil, will help to solve the problem.
Bract – a modified leaf, usually reduced in size or scale-like. Sometimes large and brightly colored.
Bramble – any shrub with thorns in the rose family; usually refers to blackberries and raspberries.
Branch crown – plant tissue that is the junction of the roots and stem that forms on the side of a strawberry plant. These only form foliage.
Broad spectrum – pesticides that affect a wide variety of pests.
Bud scales – specialized tissue that covers the terminal bud and embryonic leaves of a plant during winter.
Bud union – the location of a graft.
Bulb – an underground storage organ made up of enlarged and fleshy leaf bases and a bud.
Bulbil – a small bulb that forms along the stems of certain plants, such as tiger lilies and bladder ferns.
Bulblet – a small bulb that develops around a parent bulb and can be removed to propagate additional plants.
Button – the small heads of broccoli or cabbage that form as a result of seedlings being exposed to freezing temperatures.
Cage – an enclosure used to support a plant.
Callus – wound tissue.
Cambium – the tissue in a plant that produces new cells.
Candle – the new shoot growth on needled evergreens before the needles expand.
Cane – A long straight woody stem, usually erupting from the crown of the plant, a one-year-old shoot on a grapevine.
Canopy – top layer of a tree including branches and foliage.
Capillary action – a force that causes liquids to rise or fall when inside very small tubular spaces.
Carbon dioxide, CO2 , – a colorless, odorless gas found in the air. It is absorbed by plants and exhaled by animals.
Carnivore – a flesh-eating animal.
Caterpillar – worm-like larva of various insects, especially butterflies and moths.
Cell – the unit of plants that makes up tissues. Cells have a cell wall that encloses the protoplasm.
Chlorophyll – green pigments in plants that facilitate photosynthesis.
Cloche – a transparent plant cover used to protect plants from cold temperatures.
Coir – the fibrous material found between the hard, internal shell and the outer coat of a coconut.
Cold composting – composting under conditions where the temperatures do not rise to 140o F.
Cold frame – a glass-covered frame without artificial heat used to protect plants and seedlings.
Cole or Cole Crop – referring tovarious plants of the genus Brassica, of the mustard family, broccoli, cauliflower, cabbage, kale, etc..
Collar – a band of material used as a mechanical barrier to protect a plant from damage by insects.
Compaction – a state where soil particles are forced closely together, reducing pore space.
Complete metamorphosis – changes in body form of insects that include egg, larva, pupa and adult; also known as complex metamorphosis.
Compost tea – a low-nutrient liquid that results from placing plant debris in water and allowing it to decompose.
Composted manure – animal feces that have been aged in a pile, allowing much of the nitrogen to leach from the feces. A nonburning organic fertilizer.
Contact insecticide – a poison that must contact the body of the insect to be controlled.
Contractile – drawing together resulting in decreased size or bulk.
Cool-season crop – a crop that grows best during the cool temperatures of spring and fall.
Cool-season grass – turfgrasses that actively grow during the cooler spring and fall weather. These include Kentucky bluegrass, the fescues, ryegrasses and bentgrass.
Cordon – horizontal branches of a grapevine trained along the trellis; also called the arms. The canes left after pruning which will produce fruiting shoots and new canes.
Core aeration – increasing air penetration of the soil by removing plugs of soil. A heavy machine with hollow prongs is moved across a lawn pushing the prongs into the soil and pulling out plugs of soil.
Corm – a short, thickened, underground, upright stem in which food is stored.
Cormel – a small corm that forms around the parent corm. It can be removed and planted to propagate a new plant.
Cotyledon – the leaf or leaves of the embryo, also called seed leaves.
Cover crop – a crop that improves the soil in which it is grown.
Crop rotation – growing crops of a specific family in different areas of the garden each year to avoid soil-borne diseases and nutrient depletion.
Cross-pollination – the transfer of pollen from one plant to the stigma of another plant.
Crotch – the angle measured from the trunk of a tree to the upper surface of a branch.
Crown – the part of a plant where the root and the stem meet.
Cruciferous – Vegetables of the family Brassicaceae (also called Cruciferae) are called Cruciferous vegetables; widely cultivated, with many genera, species, and cultivars being raised for food production. The family takes its alternate name (Cruciferae, New Latin for “cross-bearing”) from the shape of their flowers, whose four petals resemble a cross.
Culinary – used in cooking.
Cultivar – also cultivated variety; a subdivision of a species, a result of human-manipulated hybridization.
Cultivation – preparation of the soil for growing plants.
Cultural control – the use of good gardening techniques to control pest populations.
Cucurbit – The plant family Cucurbitace, also known as gourd family, which includes crops like cucumbers, squashes (including pumpkins), luffas, and melons (including watermelons). The family is predominantly distributed around the tropics, where those with edible fruits were amongst the earliest cultivated plants in both the Old and New Worlds
Cuticle – a waxy or varnish-like layer covering the outer surface of leaves.
Cutin – the waxy or varnish-like material that makes up the cuticle.
Damping Off – Damping-off is a fungal disease that can kill seedlings overnight. The fungus rots the stems at the soil surface, causing the seedlings to fall over and die. A way to control this problem is with improved circulation.
Day-neutral plant – a plant that will flower under any day length.
Days to maturity – the number of days between planting the seed and first harvest.
Deadhead – To remove the spent flowers to promote further blooming, and improve the plant’s appearance. A general term. Pinching, shearing, cutting back to a flower bud and stem cutting are all methods of deadheading.
Deadleaf – To remove damaged foliage from a plant.
Deciduous – plants that drop their leaves at the end of each growing season.
Dehydration – an abnormal loss of fluids.
Desiccation – drying.
Determinate – growth that is limited.
Diameter breast high – the diameter of a tree trunk at a height of 4-1/2 feet above the ground.
Dicot – also dicotyledon; flowering plants with embryos that have two cotyledons.
Dioecious – plants that have only male or only female flowers on an individual plant.
Disease resistance – the tendency not to be infected by a particular pathogen.
Disease tolerance – the ability of a plant to continue growing without severe symptoms despite being infected by a pathogen.
Division – a method of propagation by separating and planting segments capable of growing roots and shoots.
Dormancy – a state of suspended growth or lack of visible activity caused by environmental or internal factors.
Double dig – a method of digging a garden bed which involves removing the soil to the depth of one spade blade and then digging down an equal distance, breaking up and mixing the soil.
Drift – when a pesticide is blown by wind onto nontarget organisms.
Drip irrigation – a system of tubes with small holes that allow water to drip out onto the root zone of plants. A water-conserving irrigation system.
Drip line – a line encircling a tree corresponding to the furthest extension of the branches of a tree.
Drought – a prolonged period of dryness that can cause damage to plants.
Ecosystem – a system consisting of a community of animals, plants and microorganisms and the physical and chemical environment in which they interrelate.
Element – a substance that cannot be separated into different substances. All matter is made of elements.
Endophyte – a plant living within another plant. In turfgrasses, it is a fungus within the grass plant secreting substances that repel insect pests.
Epiphyte – A plant that usually grows on another plant and gets its nutrients from the air and water.
Espalier – a plant trained to grow flat against a wall or trellis.
Established – the state of a plant when it is adjusted to the site and thriving.
Evergreen plants – plants that do not drop the current season’s leaves at the end of the growing season.
Fallow – cultivated land that is allowed to lie idle for a growing season.
Fertilization – the application of nutrients for plant growth. The union of the egg and sperm.
Fertilizer burn – the browning and in extreme cases, killing of plants from exposure to excessive nitrogen.
Fibrous root – a root system where the roots are finely divided.
Field capacity – the amount of water soil can hold against the force of gravity.
Filament – the part of the stamen that holds the anther in position for pollen dispersal.
Fine fescues – a fine-leaved turfgrass that grows well in shade, low soil moisture, low fertility and low pH. It requires well-drained, slightly dry soils. Red, hard and chewing fescues are included in this group.
Floricanes – on raspberries and blackberries, two-year-old canes which bear fruit and then die.
Food chain – a sequence of organisms in a community in which each member of the chain feeds on the member below it, as in fox, rabbit and grass.
Force – manipulation of environmental factors to make a plant blossom out of season.
Freeze date – The average date of the first hard freeze in the fall /the last hard freeze in the spring.
Friable – easily crumbled or broken
Frond – the leaf of a fern.
Frost – a covering of minute ice needles, formed from the atmosphere at night upon the ground and exposed objects when they have cooled by radiation below the dew point, and when the dew point is below the freezing point.
Frost pocket – a depression in the terrain into which cold air drains, but cannot escape.
Fruiting wood – on grapevine, the one-year-old canes that will produce the current year’s fruit.
Fungi – saprophytic and parasitic organisms that lack chlorophyll and include molds, rusts, mildews, smuts, mushrooms and yeast; singular, fungus.
Gametophyte – the phase of a life cycle which has half the normal number of chromosomes.
Genus – groups of closely related species clearly defined from other plants.
Girdling – removing the bark from a woody stem to kill the plant. Encircling a stem with a material so that the cambium layer is destroyed, killing the plant.
Glysophate – A chemical used to kill vegetation; non-specific. Round-up was the first product of this kind for home use, but there are now many other brands and generics available. Works only on actively growing plants by translocation: the plant moves the chemical throughout its system with the result that both roots and tops are killed. If spraying on lawns for weed control, be very sure that they are still completely dormant.
Grafting – the joining of two separate structures, such as a root and a stem or two stems, so that by tissue regeneration they form a union and grow as one plant.
Green manure – an annual cover crop that is turned into the soil before it flowers.
Greensand – an organic source of potassium. About 7% potash plus 32 trace elements.
Grub – short, fat, worm-like larva, especially of beetles.
Guard cells – specialized crescent-shaped cells that control the opening and closing of a stomata.
Gynoecious – has only female reproductive structures; the “female” plant.
Gynodioecious – both female and hermaphrodite plants present. In some plants, strictly female plants are produced by the degeneration of the tapetum, a shell-like structure in the anther of a flower where the pollen cells form.
Harden off – acclimated to the reduced humidity and cooler (or hotter) temperatures of the outdoors
Hardiness – the ability to withstand harsh environmental conditions.
Hardpan – a hard, compacted, often clayey layer of soil through which roots cannot grow.
Hardwood cutting – a mature, woody piece of a woody plant that is removed to asexually propagate a new individual plant.
Heave – the partial lifting of a plant out of the soil as a result of alternating freezing and thawing of the soil.
Heavy metals – the heavy metals of concern to gardeners are lead, zinc, nickel, arsenic, copper and cadmium. These metals can be toxic to plants when they accumulate to high levels in the soil.
Heeling in – covering the roots of dormant plants with soil or mulch for short, temporary periods.
Heirloom vegetables – cultivars that were popular a generation or more ago.
Herbaceous – a nonwoody plant Herbaceous plants are those plants composed of soft tissues. This includes most perennials, annuals, and biennials.
Herbicide – an agent that stops plant growth or kills a plant.
Herbivore – a plant-eating animal.
Hermaphrodite – plants whose flowers have both male and female parts
Hill planting – grouping plants in a cluster, not necessarily on an elevated mound.
Holdfast – a part of a plant that clings to a flat surface.
Honeydew – a sugary substance secreted by aphids and other juice-sucking, plant-feeding insects.
Hoop house – A structure to provide shelter for plants during the winter; constructed of arcs of support material, such as PVC pipe covered with plastic and fastened to the soil; an inexpensive temporary green house.
Horticultural oil – Refined oils which are sprayed on plants to smother pests. The older form, dormant oil, was heavy and had to be used within a very tight temperature range, typically in winter to avoid damaging the plant tissues. The newer superfine horticultural oils, also called ultarfine horticultural oils, are much lighter and have a wider safe temperature range.
Hotbed – a bed of soil enclosed by a structure with a top of glass, heated, often by manure, for forcing or raising seedlings.
Humidity – the amount of moisture in the air.
Humus – brown or black, partially decomposed plant or animal material that forms the organic portion of soil.
Hybrid – a first generation cross between two genetically diverse parents.
Hydrocool – a rapid cooling process of most fresh fruits and vegetables conducted during the immediate harvest in order to maintain the highest quality at its delivery. Other types of cooling delays the time that it takes to reach the consumer and reduces the shelf life.
Hyphae – pl. of hypha; the threads making up the mycelium of a fungus.
Incomplete metamorphosis – gradual growth of an arthropod that involves change in size, but not form.
Incubation – the growth of a pathogen so that it can enter a host.
Indeterminate – growth that is potentially limitless.
Infection – the stage when a pathogen is growing in a host and causing damage.
Inoculant – a microorganism which is introduced into the soil to improve growth of legume crops.
Inoculation – the introduction of a pathogen to a host.
Inorganic – being or composed of matter other than plant and animal; often of mineral origin.
Instar – the stage in the life of an arthropod between molts.
Internode – the area on a stem between nodes.
Interplant – growing two different intermixed crops in an area to maximize space usage.
Interstem – an intermediate stem piece that is grafted between the scion and the stock.
Irrigation – to supply water by artificial means, such as with sprinklers.
Kentucky bluegrass – a cool-season turfgrass that spreads by rhizomes. It is the most popular species for high-quality lawns in Ohio. It is very winter hardy.
Landscape fabric – a loosely intertwined fabric that is placed over the soil as a mulch to reduce weed invasion.
Larva – a stage of insect complete metamorphosis between the egg and pupal stages. The feeding, growing, nonreproductive stage of insect development.
Latent bud – a dormant bud that is capable of growth and development.
Lateral bud – smaller buds on the sides of stems, responsible for growth of leaves and side branches.
Lateritic Soil – any soil produced by the decomposition of the rocks beneath it.
Lath house – a structure consisting of a frame supporting strips of wood which are spaced to provide about 50% shade.
Layering – a method of propagation in which adventitious roots form before the new plant is severed from the parent plant.
Leach – to dissolve in water and wash away.
Leaf miner – A pest of columbine and other plants; visible as white squiggles within the leaves. Controlled by cutting back affected foliage and bagging for trash removal.
Leaf Mold – Leaf mold is a form of compost produced by the fungal breakdown of shrub and tree leaves, which are generally too dry, acidic, or low in nitrogen for bacterial decomposition.
Leaf scorch – injury to leaves due to lack of sufficient water, excessive transpiration or injury to the water-conducting system of the plant.
Loam – Loam is soil composed of sand, silt, and clay in relatively even concentration (about 40-40-20% concentration respectively). Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils. Loams are gritty, moist, and retain water easily.
Long-day plant – a plant that requires a night shorter than its critical dark period, usually 12 hours or less, to develop flowers.
Macronutrients – the nutrients needed in large amounts by plants: nitrogen, phosphorous, potassium, magnesium, calcium and sulfur.
Marginally hardy – close to the limit of hardiness that a plant can withstand. Planting plants that are marginally hardy is risky, because under the most severe conditions for that zone, the plant may not survive without extra protection.
Matted-row – a system of planting where plants are placed off center or are centered on a diagonal.
Meristem – a region of cell and tissue initiation; cells that do not mature, but remain capable of further growth and division.
Metamorphosis – the changes of form insects go through in their life cycle from egg to immature stages to adult.
Microbe – also microorganism; an organism of microscopic size.
Microclimate – the local climate of a small site or habitat.
Micronutrients – the nutrients needed in small amounts by plants: iron, manganese, zinc, copper, molybdenum, boron and chlorine.
Miscible Oil – a hydrocarbon oil that contains emulsifiers, forms a milky emulsion with water, and is suitable for use especially as a dormant spray
Miticide – a pesticide that kills mites.
Mollusk – invertebrate animals with soft, unsegmented bodies, such as clams and snails, usually enclosed in a calcium shell.
Molt – to shed the exoskeleton to accommodate growth.
Monocot – or monocotyledon, flowering plants that have embryos with only one cotyledon.
Monoecious – plants that have both male and female flowers on the same plant.
Moss – small, leafy plants that do not produce flowers or seeds. They grow in moist, shaded areas where fertility is low.
Mycoplasma – disease-causing agents similar to viruses.
Mycorrhiza – The word “Mycorrhiza” is given to a mutualistic association between a fungus (Myco) and the roots (rhiza) of the plants. This ascociation is symbiotic because the relationship is advantageous for both organisms. The macrosymbiont (the plant) gains increased exploration of the soil (rhizo sphere) with the intrincate net of hyphae that increases the uptake of water and nutrients from the soil interphase. The microsymbiont (the fungus) uses the carbon provided by the plant for its physiological functions, growth and development.
Natural – occurring in nature.
Nematodes – microscopic, elongated, cylindrical, parasitic worms that live in water and soil.
Node – the location on a stem where buds form.
Nodules – swellings on the roots of legumes where nitrogen-fixing bacteria live.
Nonselective pesticide – a poison that kills a wide variety of pest species.
Nutrients – substances a plant takes in and uses as food for growth and development.
Nymph – a stage or series of size changes between egg and adult in the life cycle of insects that go through incomplete or simple metamorphosis.
Organic – of plant or animal origin.
Organism – microscopic bacteria, fungi, bacteria, earthworms, and insects
Ovary – the swollen bottom part of the pistil that contains the ovules or immature seeds.
Overwinter – depends on the context, technically “to pass, spend, or survive the winter” but in gardening terms could also mean The process of bringing frost-tender plants through the winter by moving them indoors.
Oxygen, O2, – a colorless, tasteless, odorless gas that is 1/5 of the volume of the atmosphere.
Parasitic – an organism that lives on or in another living organism (the host) and obtains nutrition from the host.
Parthenocarpy – is the natural or artificially induced production of fruit without fertilization of ovules. The fruit is therefore seedless. Stenospermocarpy may also produce apparently seedless fruit, but the seeds are actually aborted while still small. Parthenocarpy (or stenospermocarpy) occasionally occurs as a mutation in nature, but if it affects every flower, then the plant can no longer sexually reproduce but might be able to propagate by vegetative means.
Pathogen – a disease-causing organism.
Pelletized – the coating and forming into pellets of very small seed so they are easier to handle.
Penetration – the point at which a pathogen enters a host.
Perennial ryegrass – a cool-season turf grass with seeds that germinate quickly. The cultural requirements are similar to those of Kentucky bluegrass; however, it is not quite as hardy or disease resistant as bluegrasses.
Perennials – plants that do not die after flowering, but live from year to year.
Perlite – an amorphous volcanic glass that has a relatively high water content, used as a plant growth medium. When used as an amendment it helps prevent water loss and soil compaction.
Petals – a whorl of structures that surround the inner reproductive organs of a flower. Together they are called the corolla. They often attract insects by color or nectar, facilitating pollination.
pH – The acidity or alkalinity of a material. (see soil pH)
Pheromone – a chemical substance that convey information to and produce specific responses in certain animals.
Phloem – the part of the vascular system that moves food through the plant.
Photoperiodism – responses of plants to the relative lengths of light and dark cycles.
Photosynthesis – the production of sugar from carbon dioxide and water in the presence of chlorophyll, activated by light energy and releasing oxygen.
Phototropism – the bending of a plant toward the direction of more intense light.
Pinch – To remove the spent bloom or the growth tip of a plant by pinching it off with the fingers. It encourages re-bloom and compact growth, breaking off the terminal growing point of a plant to encourage axillary buds to grow.
Pith – the soft, spongy central cylinder of parenchymatous tissue in the stems of dicotyledonous plants
Pistil – the female part of the flower, consisting of one or more carpels and enclosed ovules.
Pollard – a tree cut back to the trunk to make a dense cluster of branches and foliage.
Pollen – the microspores that carry the male gametophyte of seed plants.
Pollination – the transfer of pollen from the anther to the stigma.
Pollinator – an insect or other vehicle by which pollen is carried from one flower to another. A plant that provides pollen for a self-infertile plant.
Post-emergent herbicide – a pesticide that kills plants after they have grown to seedling stage or beyond.
Potpourri – a mixture of dried flower petals with herbs and spices used for its fragrance.
Potting medium – material used for growing plants in containers. Mixes may include vermiculite, perlite, sand, peat, charcoal, loam and fertilizer.
Pot Up – To transplant a seedling or plant to a pot or similar container.
Powdery mildew – A fungal disease that affects many plants.
Pre-emergent herbicide – a pesticide that kills plants as they germinate.
Primocanes – on raspberries and blackberries, new, first-year canes.
Procumbent – having stems that trail along the surface.
Propagation – to increase the number of plants by sexual or asexual means
Protozoans – organisms made up of a single cell or a group of basically identical cells.
Prune – to cut back parts of plants for better shape, disease control or improved fruiting.
Pupa – a stage in complete metamorphosis when an insect transforms from the larval to adult stage of development.
Raised bed – a gardening area where the soil has been elevated above ground level. This gardening technique is especially used where soil drainage is poor. Beds can be raised in a structure of wood, brick, cement blocks, etc.
Rasping – mouth parts that are rough and used to scrape a surface to feed.
Reel mower – a mower with multiple blades mounted on a cylinder. The blades cut against a bar. It makes precise cuts and is ideal for lower mowing heights. The blades require professional sharpening. These mowers are safer to use than rotary mowers.
Renewal spur – on grapevines, the cane pruned to one or two nodes on the cordon; becomes the fruiting cane the following year.
Renovation – removing an old planting and putting in a new one or removing and replacing only part of a planting. In strawberry culture, this process involves removing the leaves of the plants and cultivating the aisle to reduce the width of the row of plants to no more than 15 inches.
Respiration – the process where food is oxidized (burned) to release energy.
Rhizome – an underground, horizontal stem.
Root – the portion of the plant usually found below ground. They are distinguished from stems by not having nodes.
Root girdling – encircling roots at or below the surface of the ground that tend to strangle the plant.
Root hairs – tubular outgrowths of surface cells of the root.
Root prune – to cut back the roots of a plant to encourage them to develop more fibrous roots or to reduce the mass of roots. Usually done before transplanting established plants or repotting houseplants.
Rooting hormone – a chemical that stimulates the growth of roots.
Rootstock – the root onto which a scion or bud is grafted or budded.
Rotary mower – a mower with a blade that spins in a horizontal plane from a central rod. Its advantages are the ability to cut tall grass, versatility of movement, a less expensive purchase price and blades that can be easily sharpened.
Row cover fabric – a loosely woven translucent fabric used to keep insect pests off crops. It also functions as a cloche.
Saprophyte – an organism that obtains nutrition from dead organic matter.
Scale – Sucking insect pests, scale need to be controlled early. Keep a careful watch on susceptible plants. Other than selecting resistant varieties of new plants, the most effective control is the use of ultra fine horticultural oil, usually requiring at least 3 applications 6-7 days apart until no new scale is detected.
Scarification – the physical or chemical treatment given to some seeds in order to weaken the seed coat sufficiently for germination to occur.
Scion – the upper part of the union of a graft.
Scorch – injury to leaves due to lack of sufficient water, excessive transpiration or injury to the water-conducting system of the plant.
Seed – the organ that forms after fertilization occurs.
Seed leaves – A germinating seed first produces leaves that are atypical to the mature leaves of the species. These leaves help to nourish the plant as it begins its development.
Selective herbicide – a pesticide that kills only one type of plant, for example broad leaf herbicides only kill broad leaf weeds, not turf grasses.
Self-cleaning – herbaceous plants that drop spent blossoms, thus not requiring deadheading.
Sepals – structures that usually form the outermost whorl of a flower. Together, they are called the calyx.
Sesquioxide – an oxide containing three atoms of oxygen combined with two of the other constituent in the molecule.
Sewage sludge – the solid matter that settles out during the treatment of sewage.
Sexual reproduction – production of new generations involving the exchange of chromosomes from both a male and female parent.
Sharp sand – a coarse sand used in building.
Short-day plant – a plant that requires a night longer than its critical dark period, usually 12 hours or more, to develop flowers.
Side-dress – to apply fertilizer to the side of a row of growing plants or around single plants.
Slice seed – a technique used to sow seed. A machine cuts or slices grooves into the lawn or soil and drops seeds directly into the grooves. It is used to fill in a thinning lawn without disturbing the existing grass excessively.
Soaker hose – a porous tube that allows water to seep from it; used to irrigate plants. It is used to conserve water and to avoid wetting plant foliage.
Softwood cutting – a non-woody piece of a woody plant that is cut from the stock plant to asexually propagate a new individual plant.
Soil – The top layer of the earth’s surface, consisting of rock and mineral particles mixed with organic matter.
Soil conditioner – any material added to soil to improve its structure, texture, tilth or drainage.
Soil ph – The acidity or alkalinity of the soil. The pH affects the plant’s ability to take up essential nutrients. The optimum pH varies from species to species. In general, most plants will grow in a soil pH of 6.5-7.0.
Soilless mix – potting medium that contain a mixture of ingredients from the materials listed for potting medium, but no mineral soil.
Soluble salt – salts from fertilizers and tap water that are dissolved in water.
Solvent – a liquid that can dissolve a substance.
Species – a group of closely related individuals that have the potential to reproduce with each other; a unit of classification.
Specific epithet – the second name of the binomial given to a species; for instance, “rubrum” is the species epithet of Acer rubrum.
Sphagnum moss – Sphagnum is a genus of between 151 and 350 species of mosses commonly called peat moss, due to its prevalence in peat bogs and mires. A distinction is made between sphagnum moss, the live moss growing on top of a peat bog on one hand, and sphagnum peat moss (North American usage) or sphagnum peat (British usage) on the other, the latter being the decaying matter underneath. Sphagnum can hold large quantities of water inside their cells; some species can hold up to 20 times their dry weight in water, which is why peat moss is commonly sold as a soil conditioner and/or used in seed starting mixtures.
Spines – a sharp-pointed woody structure, usually a modified leaf or leaf part.
Spore – a minute reproductive body produced by primitive organisms, such as ferns and fungi.
Sporophyte – the part of a life cycle when the full complement of chromosomes are present.
Spreader-sticker – substances added to pesticides to make them spread over and stick to a surface more readily.
Spur – on grapevines, canes pruned to 1 to 4 nodes.
Square-foot gardening – a system of gardening developed by Mel Bartholomew that uses 4 foot by 4 foot plots subdivided into 1-foot squares for growing a specific number of a particular type of vegetable to maximize space and facilitate ease of maintenance.
Stake – a piece of pointed wood or metal that is driven into the ground to support a plant.
Stamen – the male part of the flower. It consists of the anther and the slender filament that holds it in position.
State specialists – professors at land grant universities who provide expertise for Extension workers.
Stem – the main trunk of a plant. It develops buds and shoots.
Stem back – To cut back the flowering stem of a plant to the next growth point, either a leaf node or to the crown.
Stigma – the part of the pistil that receives the pollen grains; usually the top of the pistil.
Stock plant – a plant used as a source for cuttings.
Stomata – an opening or pore in leaves that is surrounded by guard cells.
Strain – a subgroup of a species; the descendants of a common ancestor.
Stratification – storing of seeds at low temperatures under moist conditions in order to break dormancy.
Style – the slender part of a pistil between the stigma and the ovary.
Succession planting – planting portions of a crop over a period of time to get a continuous harvest over a long period of time.
Succulent – having tender, new growth or thick, fleshy tissues which store water, such as cactus.
Sucker – a shoot arising from the root or lower part of the stem of a plant.
Sun scald – plant injury caused by exposure to bright sunlight, excessive heat and/or wind.
Susceptible host – an organism that can be infected by a pathogen.
Swale – a low-lying or depressed and often wet stretch of land; also : a shallow depression on a golf fairway or green .
Symbiotic – a relationship in which two or more dissimilar organisms live together in close association.
Symptom – evidence of disease or damage.
Synthetic – substances produced by chemical or biochemical means.
Systemic – a group of pesticides that are absorbed into the tissues of plants, thereby poisoning the organisms that feed on the plant.
Tall fescue – a coarse, clump-forming turf grass that tolerates low fertility, heavy wear, heat and drought and has good insect and disease tolerance. Young seedlings are not cold tolerant, but mature plants survive most Ohio winters.
Taproot – a stout, tapering primary root that has limited side branching or fine roots.
Temperate – moderate; the zones between the tropics and the polar regions of the earth.
Tender Perennial – A true perennial with a predictably long life in the proper climate, but unable to endure the extremes of the climate in which it will be grown. Many of the plants we know as annuals are actually tender perennials.
Tendril – a slender, coiling modified leaf or leaf part. These help plants climb.
Tepee – a tripod of stakes used to support climbing plants.
Terminal bud – large, vigorous buds at the tips of stems.
Terrace – a series of flat platforms of soil on the side of a hill, rising one above the other.
Thatch – an intertwined layer of dead and living roots, stems and blades of grass plants. It holds water, pesticides and fertilizer like a sponge, preventing them from reaching the roots.
Thermophilic – growing best in a warm environment (of bacteria) growing best at temperatures between 122° and 150° F (50° and 60° C)
Thorax – the middle of the three major divisions of the arthropod body.
Topiary – training, cutting and trimming of plants into ornamental shapes.
Top dress – To scatter material at the base of a plant without working it into the surrounding soil.
Topsoil – uppermost layer of soil, usually darker and richer than the subsoil.
Toxicity – intensity of a poison.
Transpiration – the loss of water from plant tissues in the form of vapor.
Transplanting – digging up a growing plant from one location to plant it in another location.
Trellis – a frame of latticework used as a support for climbing plants.
Tropical – regions of the earth lying between the Tropic of Cancer and the Tropic of Capricorn extending around the equator where the temperature and humidity are high.
Trunk – the main stem of a tree, shrub or vine.
Tuber – an enlarged, underground stem that stores food.
Turgid – the condition of a cell, tissue or plant when it is filled with water so that it is firm; not wilted.
Umbel – an inflorescence in which a number of flower stalks or pedicels, nearly equal in length, spread from a common center.
Understock – the part of a plant to which a graft is attached.
Variegated – plant parts having different pigments resulting in more than one distinct color or shade on the foliage.
Variety – a subdivision of a species; occurs through natural hybridization.
Vascular system – the tissue in a plant that moves fluids through the plant.
Vector – an organism that transmits a disease-causing pathogen.
Vegetable – A plant cultivated for an edible part
Vegetative – plant parts and processes concerning growth and nutrition and not reproduction.
Venation – the pattern of veins.
Vermiculite – a clay mineral used in its heat expanded form as a bedding material for young plants
Vernalization – to shorten the growth period of a plant by chilling or other special treatment of it, its seeds, or its bulbs.
Viable – capable of growing or developing.
Virus – a group of submicroscopic infective agents that are considered nonliving complex molecules.
Warm-season crops – crops that are harmed by frost and do not grow well until the temperatures are in the 70s.
Whip – a very young tree that still has a flexible trunk.
Wide-row planting – growing the smaller vegetable crops in a space up to 3 feet across to better utilize space while reducing weeding.
Wilting point – the amount of water in a soil when a plant cannot obtain enough water to remain turgid.
Winter dormancy – The state of reduced growth and function which permits the plant to survive the extremes of winter.
Winter over – Same as overwinter To live through the weather conditions of winter and return to vitality the following year.
Witches’-broom – a dense, bushy growth of branches and foliage caused by a parasitic fungus and mites or poor pruning techniques.
Work up – To clear a space of undesirable plants and other materials, dig deeply, top with amendments and work the amendments thoroughly through the soil. After working up, the bed must be brought to grade, or smoothed to the desired finished surface.
Xeriscaping – Pioneered in Denver, xeriscaping is a series of practices used to reduce the amount of supplemental irrigation used in gardens. The practices need to be carefully considered with the climatic conditions of the particular area in which the garden is sited.
Xylem – the part of the vascular system that moves water and minerals through the plant.
Zones, Cold/Heat – The American Horticultural Society has developed maps of the amount of heat expected in a given area or zone. Individual plants are rated for their heat zone tolerance. The United States Department of Agriculture long ago developed a map of the amount of cold expected in a given area or zone. Individual plants are rated for their cold zone tolerance.
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