Terms: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Abscission: The shedding of leaves, flowers, or fruits following the formation of scar tissue in a plant. A bscisic acid is the plant hormone involved in leaf abscission.

Acid: A substance that has a pH of less than 7, which is neutral. Specifically, an acid has more free hydrogen ions (H + ) than hydroxyl ions ( OH - ).

Active transport : Transport of molecules against a concentration gradient (from regions of low concentration to regions of high concentration) with the aid of proteins in the cell membrane and energy from ATP.

Adenosine triphosphate (ATP) : A common form in which energy produced in the light reaction of photosynthesis stored in living systems; consists of a nucleotide (with ribose sugar) with three phosphate groups.

Adsorption : The accumulation of gases, liquids, or solutes on the surface of a solid or liquid. The attachment of nutrient ions to the surface of clay and organic colloids within soil.

Aerobic respiration : Respiration in which molecular oxygen is consumed and carbon dioxide and water are produced. Opposite of anaerobic respiration.

Aeroponics : A variation of hydroponics that involves the misting of plant roots with nutrient solution. Commonly used in cloning machines, but can be used for full term growth. Advantageous due to the higher levels of oxygen present in the root zone. It also reduces the amount of energy a plant uses to uptake nutrient by delivering food and water in small drops as opposed to the water accumulating on the root for absorption.

Affinity : An attractive force between two particles.

Algae : Any of various chiefly aquatic, eukaryotic, photosynthetic organisms, ranging in size from single-celled forms to giant kelp.

Alkaline : or, basic. Having a pH greater than 7. Having a relatively low concentration of hydrogen ions

Alkalinity : The alkali concentration or alkaline quality of an alkali-containing substance.

Amino acid : A ny one of a class of simple organic compounds containing carbon, hydrogen, oxygen, nitrogen, and in certain cases sulfur. These compounds are the building blocks of proteins and enzymes. They are characterized by the presence of a carboxyl group (COOH) and an amino group (NH₂) attached to the same carbon at the end of the compound.

Ammonium nitrate : C hemical compound, NH 4 NO 3 , that exists as colorless, rhombohedral crystals at room temperature but changes to monoclinic crystals when heated above 32°C. It is extremely soluble in water and soluble in alcohol and liquid ammonia. It is prepared commercially by reaction of nitric acid and ammonia . Major uses are in fertilizers and explosives . For fertilizers it is in the form of small clay-coated pellets. For explosives it is sometimes mixed with other substances, e.g., TNT, so that it is more easily detonated. It is also used in solid-fuel rocket propellants, in pyrotechnics, and in the production of nitrous oxide.

Ampere (AMP): this is the unit used to measure strength of an electric current.

Anaerobic respiration : Respiration in which molecular oxygen is not consumed.

Angiosperms : a flowering plant

Animal welfare : The health and well being of animals is central to organic principles. Health should be defined as a positive physical and mental state whereby the livestock are robust and able to resist diseases. Positive animal welfare means the satisfaction of 'all the animals' needs, including their behavioral needs, not just the avoidance of cruelty. The foundation stones of animal welfare are good nutrition, careful management and the use of appropriate breeds.

Anions : Anions are negatively charged ions such as sulfate SO 4 - and phosphate PO 4 -

Annual : Maturing and living one season only.

Anther : The pollen producing tip of a stamen; part of a flower.

Apical meristem : Group of cells at the growing tip of a branch or root. It divides cells to create new tissues.

Apoplast : The extracellular region that includes the cell wall and middle lamella. The apoplast is found in the non-living parts of the root.

Aquaculture : F arming of plants and animals that live in water, such as fish, shellfish, and algae. The other end of the system from plant growth when growing aquaponically

Aquaponics : The integration of aquaculture (the raising of marine animals, such as fish) with hydroponics; the waste products from the fish are treated and then used to fertilize hydroponically growing plants.

Arable : Suitable for plowing.

Arthropods : Invertebrate animals with jointed legs. They include insects, crustaceans, sowbugs, springtails, arachnids (spiders), and others.

Asexual reproduction : In asexual reproduction (gemmation, fission, etc.), the detached portions of the organism develop into new individuals without the intervention of other living matter.

Assimilation : To absorb and incorporate; digest.

Bacteria : Primitive, unicellular, microscopic organisms that lack a cell nucleus and other organelles, obtain soluble food by absorption, and reproduce by simple cell division. They include the photosynthetic cyanobacteria (formerly called blue-green algae), and actinomycetes (filamentous bacteria that give healthy soil its characteristic smell). T hese are the most abundant of all organisms --and the simplest (having only a single cell). They are beneficial to decay mechanisms, but many kinds are considered disease organisms. Examples of bacterial diseases include blights and some types of rot and wilt.

Ballast : a device used to regulate flow of electricity to match the needs of a specific bulb.

Base : A substance that has a pH of more than 7, which is neutral. A base has less free hydrogen ions (H + ) than hydroxyl ions ( OH - ).

Binding site : region on a protein where specific ligands bind.

Biocatalyst : A substance, especially an enzyme, that initiates or modifies the rate of a chemical reaction in a living body; a biochemical catalyst.

Biodiversity : The diversity of living organisms in any one place --whether in a handful of soil, the garden, the region, or the planet. Species richness contributes heavily to a healthy environment on every level, creating balance through an elegant distribution of the work of the planet. Diversity helps to insure that a single pest, event, or disease doesn't cause irreparable damage to an entire ecosystem. In the same way, growing a variety of crops while supporting a diverse community of organisms will help insure you a successful harvest year after year.

Biodynamic cultivation : Originated by Rudolph Steiner, it is a form of cultivation that originates through Eastern philosophy and cosmic influences and has been referred to as "spiritual science".

Biological control : A term used to describe the use of natural organisms to reduce the effects of undesirable organisms (pests) and to favor desirable organisms such as crops, trees, animals, beneficial organisms or insects.

Biostimulant : a substance that is not a plant nutrient or pesticide but which in some manner has a positive impact on plant health. The biostimulant may enhance metabolism, increase chlorophyll efficiency and production, increase antioxidants, enhance nutrient availability and increase the water holding capacity of the soil.

Biosythesis : Formation of a chemical compound by a living organism. Also called biogenesis.

Blight : Affecting a long list of different plant species, each in a slightly different manner, blight is a bacterial disease. The disease spreads rapidly in wet conditions, generally turning whole or parts of leaves brown and black. Highly contagious: if you suspect your plants are suffering from blight, trim off dead or dying plant material at least two inches below infected material, sterilizing your pruners between each cut.

Blood meal : This organic fertilizer is very high in nitrogen and is very soluble in water (unlike most other dry organic fertilizers). It also contains plant growth regulators. All this together means that its effect is strong and quick, but its power will only last a short while, especially in wet weather. When applying blood meal, take care, as it will easily burn a plant's leaves.

Bone meal : An organic fertilizer that is applied to increase phosphorus levels in the soil (or compost). Although phosphate rock can also be used for this, bone meal will break down in the soil considerably faster and can thus be used as a quick fix; but this also means that it will not have a long term effect on the soil.

Bryophyte : Plant that lacks vessels, including the mosses, liverworts, and hornworts.

Burn : Leaf tips that turn noticeably dark from excess fertilizers or salts. Usually occurs from the edges or tips of leaves and is a result of "water stress". Water stress occurs from the reversal of the gradient plants use to utilize water via osmosis. By having too high a concentration of ions outside the root, water goes from a lower to a higher concentration, leaving the plant, in turn, "burning" it.

Calvin cycle (aka Calvin-Benson Cycle or Carbon Fixation): The non-light requiring reactions (dark reactions) of photosynthesis. Series of biochemical, enzyme-mediated reactions during which atmospheric carbon dioxide is reduced and incorporated into organic molecules, eventually some of this forms sugars. In eukaryotes, this occurs in the stroma of the chloroplast.

Calyx : The calyx is the outermost whorl of a flower. It consists of sepals , which are green. The sepals may be free from each other in the same flowers of some plants or fused to form a cup in flowers of other plants. The calyx encloses and protects the inner whorls in the bud stage . Since the sepals contain chlorophyll, they can also synthesize food

Cambium : Primary growth in plants is accomplished by the apical meristem, which accomplishes the elongation of the plant. Secondary growth is made possible by the lateral meristem, which increases the girth of the plant. This actively growing tissue is generally only present in woody species and is called the cambium. It produces secondary xylem and phloem.

Canopy : Layer of vegetation elevated above the ground, usually of tree braches and epiphytes. In tropical forests, the canopy may be more than 100 feet above the ground. In indoor gardening it is simply the uppermost level of vegetation.

Capillary action : T he means by which liquid moves through the porous spaces in a solid, such as soil or plant roots due to the forces of adhesion, cohesion, and surface tension. Capillary action is essential in carrying substances and nutrients from one place to another in plants.

Carbohydrate : Any of a group of organic compounds that includes sugars, starches, celluloses, and gums and serves as a major energy source in the diet of plants and animals. These compounds are produced by photosynthetic plants and contain only carbon, hydrogen, and oxygen, usually in the ratio 1:2:1. Glucose is the major plant carbohydrate and the end product of photosyntheis.

Carbon cycle : The Carbon Cycle is a complex series of processes through which all of the carbon atoms in existence revolve and rotate.

Carbon dioxide : A heavy colorless gas that does not support combustion, dissolves in water to form carbonic acid, is formed in respiration and in the decay or combustion of animal and vegetable matter. It is absorbed from the air by plants in photosynthesis, being the primary source of Carbon for growing plants. It occurs naturally in the atmosphere at .03%.

Carbon-Nitrogen ratio : The ratio of the weight of organic carbon to the weight of total nitrogen (mineral plus organic forms) in soil or organic material. Usually referred to in regards to composting. Needs to be 30:1, or 2:1 by weight, for proper decomposition for composting.

Casparian Strip : A layer in endodermis that functions as a selective barrier allowing absorption of desirable elements, but blocking absorption of harmful elements. Made up of suberin, it is impervious to water. Named after its discoverer.

Catabolism : The metabolic breakdown of complex molecules into simpler ones, often resulting in a release of energy.

Catalyst : A catalyst is a substance that increases the speed of a chemical reaction without being consumed or altered by the reaction.

Cations : Cations are positively charged ions such as calcium Ca + , Magnesium Mg + , and Sodium Na +2 .

Cation Exchange Capacity (CEC): The clay and organic components of the soil have a negative charge. As a result of these charges, positively charged ions (cations) such as hydrogen H + , potassium K + , ammonium NH + 4 , calcium Ca 2+ , magnesium Mg 2+ , aluminum Al 3+ , etc. may be held at the surface of the clay or organic particles and exchanged with other ions in the solution or with ions at the plant root's surface. This ability of a soil to hold cations is termed its cation exchange capacity (CEC). Since many cations are plant nutrients the cation exchange capacity is a measure of the soil's ability to hold such nutrients. Expressed in milliequivalents per 100 grams or per gram of soil (or other exchangers such as clay).

Cell : Fundamental structural unit of all life. The cell consists primarily of an outer plasma membrane, which separates it from the environment; the genetic material (DNA), which encodes heritable information for the maintainance of life; and the cytoplasm, a heterogeneous assemblage of ions, molecules, and fluid.

Cellulose : A polysaccharide made up of many glucose molecules chemically bonded together. The most abundant compound on earth. It comprises the bulk of cell walls of plants where it occurs as microfibrils.

Charge : The state of an atom that has lost or gained an electron.

Chelate : A chemical compound in the form of a heterocyclic ring, containing a metal ion attached by coordinate bonds to at least two nonmetal ions; can be in the form of humic acids, fulvic acids, or amino acids.

Chemical fertilizer : Defined as any inorganic material of wholly or partially synthetic origin that is added to the soil to sustain plant growth. Many artificial fertilizers contain acids, such as sulfuric acid and hydrochloric acid, which tend to increase the acidity of the soil, reduce the soil's beneficial organism population and interfere with plant growth.

Chemical specificity : The ability of a proteins binding site to bind specific ligands; the less ligands a protein can bind, the greater its specificity.

Chemiosmotic phosphorylation : The process where energy from oxidations is used to separate H+ ions across a protein gradient to produce ATP. Also referred to as oxidative phosphorylation.

Chlorophyll : The green pigment of plant cells necessary for photosynthesis that captures light energy and converts it into chemical energy. Found in the chloroplasts of plant cells. It is the pigment that makes plants green because it absorbs red and blue and reflects green. Chlorophyll is highly efficient at absorbing light energy, and is essential to photosynthesis.

Chloroplast : An organelle containing chlorophyll. There are many "organelles" that contribute to the function of a single cell. In plants cells, the organelle that carries out photosynthesis is called the chloroplast.

Chlorosis : A condition in plants resulting from the failure of chlorophyll to develop caused by a deficiency of an essential nutrient. Leaves of chlorotic plants range from light green through yellow to almost white. Chlorosis may be a symptom of a number of different plant ailments, including mineral deficiencies (commonly, iron) and some diseases. It occurs as a result of reduced chlorophyll production, turning newer (usually) growth yellow. In established leaves, areas between the veins yellow first.

Clay : A sedimentary material with grains smaller than 0.002 millimeters in diameter.

Clone : A plant that has been produced through asexual reproduction (i.e. cuttings, layering, and tissue culture) and is an exact replica of the "mother" plant.

Cloning : A cell, group of cells, or organism that are descended from and genetically identical to a single common ancestor, such as a bacterial colony whose members arose from a single original cell. An organism descended asexually from a single ancestor, such as a plant produced by layering or a polyp produced by budding.

Coenzyme : A nonproteinaceous organic substance that usually contains a vitamin or mineral and combines with a specific protein, the apoenzyme, to form an active enzyme system.

Cofactor : A substance, such as a metallic ion or coenzyme, which must be associated with an enzyme for the enzyme to function.

Collenchyma cells: Collenchyma tissues are mainly found under the epidermis in young stems in the large veins of leaves. The cells are composed of living, elongated cells running parallel to the length of organs that it is found in. Collenchyma cells have thick cellulose cell walls which thickened at the corners. Intercellular air spaces are absent or very small. The cells contain living protoplasm and they sometimes contain chloroplasts. Primary function is strengthening and supporting the developing plant.

Color-rendering Index (CRI): Color rendering is a measure of lighting quality. It is measured on an index from 0-100, with natural daylight equal to 100. Lamps with a high color-rendering index make objects appear more true to life. Plants can grow better with a higher color rendering index light source. But generally the higher the CRI the lower the lamp efficiency. Hence, MH light being closer to sunlight relative to HPS, but emitting less lumen per watt, or relative amount of light. A CRI of 85 or higher is considered good.

Color Temperature : Color temperature is a measure of the color appearance of light not the actual temperature. Light sources that appear bright white to blue-white have a high color temperature (3600K and above) and are described as "cool". Sources that appear yellow-white to red-white have a low color temperature (3600K and below) and are described as "warm". Daylight is considered to be around 5500K.

Companion planting : Utilizing the symbiotics and interrelationships of various plants to replicate a balanced ecosystem so as to accumulate predators and prey in the same areas therefore creating a check and balance system so as to control pest and disease problems.

Complete fertilizer: Containing all of the necessary elements a plant needs to grow. Miracle Grow, Peter's, etc. are not complete because they rely on the soil to bring the completion of fertilization. Products that are not "complete" will result in extreme deficiencies in plant growth and eventual non-production is utilized in a soilless scenario.

Compost : By piling kitchen scraps and garden debris in a bin or heap, gardeners create an ideal habitat for decay organisms. These microorganisms break organic material down to form humus. In addition, the heat inside the pile from all the biologic activity will kill off many disease organisms and unwanted seeds. Compost piles benefit from the addition of manures (for their high nitrogen count and the beneficial bacteria they harbor), occasional watering (so that it is moist not wet), and frequent turning (for aeration).

Compost tea : An infusion made by leaching water through compost, sometimes with nutrients added, such as molasses and kelp, to encourage certain organisms. Soluble organic matter and the organisms in the compost are rinsed out of the solid phase and left suspended in the water. This "liquid compost" is easier to apply than solid compost.

Corolla : The corolla is the "flower" part of the flower. It is often brightly of conspicuously colored and/or creating inviting aromas so as to attract beneficial insects to help in pollination.

Cortex : The cell layers occurring between the epidermis and the stele or vascular cylinder.

Cotyledon : The "seed leaves" or "starter leaves" produced by a seed plant embryo. They serve to absorb nutrients packaged in the seed, until the seedling is able to produce its first true leaves and begin photosynthesis.

Covalent bond : A chemical bond formed by the sharing of one or more electrons, especially pairs of electrons, between atoms.

Cover crop : A crop, such as winter rye or clover, planted between periods of regular crop production to prevent soil erosion and provide humus or nitrogen for the next planting. Cover crops have become interchangeable with green manures.

Cross-pollination : Transferring pollen from the flowers of one plant of a species to the stigma of another plant of the same species. In other words, from pepper plant to pepper plant. The crossing of different types of pepper plants can result in trouble identifying or maintaining the strain.

Current : Current is what flows on a wire or conductor, like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) amperes or amps.

Cuticle : Waxy layer which seals the outer surface of land plants, helping to retain moisture.

Cytokinin : any of a class of plant hormones that promote cell division and growth and delay the senescence or aging of leaves.

Cytoplasm : the substance inside a cell which surrounds the cell's nucleus

Damping-off fungus : Disease that attacks young seedlings and cuttings causing stem to rot at base. Over watering and cool wet soils favor development of the disease. The damping-off fungi may attack the seed prior to germination, or they may attack after the seed has germinated but before the seedling has emerged above the soil line. Infected seed becomes soft and mushy turning a brown to black color, and it eventually disintegrates. Seeds that have germinated and become infected develop water-soaked spots that enlarge and turn brown. The infected tissue collapses, resulting in death of the seedling. Penetration and death of seeds before they emerge is termed preemergence damping-off.

Dark reaction : The photosynthetic process in which food (sugar/carbohydrate) molecules are formed from carbon dioxide from the atmosphere with the use of ATP and NADPH; can occur in the dark as long as energy source is present.

DDT : (C₁₄H₉C_l5) Dichlorodiphenyltrichloroethane; a colorless contact insecticide, toxic to humans and animals when swallowed or absorbed through the skin, that has been banned in the United States for most uses since 1972, mostly as a result of Rachel Carson's book "Silent Spring".

Decomposition : The biochemical breakdown of organic matter into organic compounds and nutrients, and ultimately into its original components. Results in humus, the lowest form of organic decomposition.

Deductive reasoning : Reasoning from the general to the particular (or from cause to effect).

Desalinization : T he removal of salts from saline water to provide freshwater. This method is becoming a more popular way of providing freshwater to populations. Israel leads the world in this technology.

Determinate growth : not continuing to grow indefinitely at the apex.

Detritus : Loose matter resulting from the wearing away or disintegration of a tissue or substance.

Dicots : A flowering plant with two embryonic seed leaves or cotyledons that usually appear at germination.

Dioecious : A plant species is said to be dioecious when its male and female reproductive organs are carried on separate individual plants of the same species. When a plant species is dioecious, at least one male plant must be present in a group for the fruit-bearing female plants to be pollinated. By contrast, "monoecious" plants are plants having unisexual reproductive organs or flowers, with the organs or flowers of both sexes borne on a single plant.

Ecosystem : A term used to describe a system of interactions between living organisms occupying the same environment.

Effluent : Something that flows out or forth, especially a stream flowing out of a body of water, an outflow from a sewer or sewage system, or a discharge of liquid waste, as from a factory or nuclear plant.

Electrical conductivity (EC): the ability of a solution to carry electrical energy as a result of the elements and compounds in solution. The more ions dissolved in solution the higher the EC. 1.0 EC is equivalent to 700 PPM.

Electric circuit : A closed path followed or capable of being followed by an electric current. A configuration of electrically or electromagnetically connected components or devices.

Electron transport : C oupled series of oxidation/reduction reactions during which ATP is generated by energy transfer as electrons move from high reducing state to lower reducing state.

Embolism : Air bubbles can form in the vessels that transport the water taken up through the xylem towards the aboveground parts of the plant after taking a clone and exposing it to air for too long. This results in the plant being unable to begin the process of root development and subsequent death. A rooting gel 9as opposed to powder) or taking a cutting under water are two ways to help prevent embolism and bolster success rate.

Embryo : An organism in its early stages of development, especially before it has reached a distinctively recognizable form.

Endemic : Prevalent in or peculiar to a particular locality or region, as in a disease or plant. For example, Venus flytraps are endemic to a 50-mile radius around Wilmington, NC.

Endodermis : The innermost layer of cortical cells ("inner skin") found in all roots next to the vascular cylinder. The endodermis contains a Casparian strip.

Enzyme : Any of numerous proteins or conjugated proteins produced by living organisms and functioning as biochemical catalysts.

Epidermis : The outer most layer of cells of a growing plant.

Epiphyte : A plant that grows upon another plant. The epiphyte does not "eat" the plant on which it grows, but merely uses the plant for structural support, or as a way to get off the ground and into the canopy environment.

Essential oils : a class of volatile oils, extracted from plants, fruits, or flowers, having each its characteristic odor, and hot burning taste. They are used in essences, perfumery, etc., and include many varieties of compounds. Essential oils make a watermelon jucier and a strawberry sweeter.

Eukaryote : A single-celled or multicellular organism whose cells contain a distinct membrane-bound nucleus.

Evaporation : T he process of liquid water becoming water vapor, including vaporization from water surfaces, land surfaces, and snow fields, but not from leaf surfaces- this is termed transpiration.

Exudate : A substance that oozes from plant pores.

Fair Trade: Fair trade certifiers examine the practices of farmers and companies looking for a commitment to social justice. Parameters include: Paying a fair wage in the local context, offering employees opportunities for advancement, providing equal employment opportunities for all people, particularly the most disadvantaged, engaging in environmentally sustainable practices, being open to public accountability, building long-term trade relationships, providing healthy and safe working conditions within the local context, providing financial and technical assistance to producers whenever possible.

Fishmeal : Like fish emulsion, fishmeal is high in nitrogen, but its NPK ratio is generally a bit more potent, at somewhere about 5-3-3. And, unlike the emulsion, fishmeal is a dry organic fertilizer.

Flower : Collection of reproductive structures found in flowering plants.

Foliar feeding : Using a mister or spray bottle to deliver fertilizer solution or other plant promoting materials directly to the foliage. Used primarily as a deficiency correction technique, but used outside of deficiency is just another level of feeding.

Food security : When all people at all times have both physical and economic access to sufficient food to meat their dietary needs for a productive and healthy life.

Foodshed :

Footcandle : A unit of illumination equal to the intensity of one candle at the distance of one foot.

Fruit : In flowering plants, the structure which encloses the seeds. True fruits develop from the ovary wall, such as bananas and tomatoes, though not all fruits are edible, such as the dry pods of milkweed or the winged fruits of the maple.

Fungus : A non-photosythetic, chiefly multicellular organism only able to use carbon, nitrogen, etc. as starting materials for synthesis of its essential foods. Some are good (mycchorizae), some are bad (fusarium).

Fusarium : any of several fungal diseases that afflict plants; commonly called dry rot or wilt.

Gall : Crown gall infection is caused by various bacteria of the genus Agrobacterium. The disease affects a wide range of plants including deciduous fruits, vine and berry fruits, vegetables and ornamentals. Within these groups of plants there is no known cultivar resistance. The bacterium infects the plant through a wound, usually at ground level or on the roots, and transfers a tumerogenic (cancerous) factor to some plant cells. These cells then start dividing uncontrollably, forming galls of undifferentiated tissue that restrict the normal functions of the plant.

Gametophyte : P hase of plant life cycles in which the gametes, i.e., egg and sperm, are produced. A gametophyte is the haploid structure or phase of life of a sexually reproducing plant. Each cell of a gametophyte contains one complete set of chromosomes. The gametophyte can be the dominant part of the plant's life cycle as in mosses, or very reduced as in flowering plants (angiosperms), where the female form (ovule) is known as a megagametophyte and the male form (pollen) is called a microgametophyte.

Genetically Modified Organism (GMO): The 41st Edition of the International Air Transport Association Dangerous Goods Regulations defines GMOs as microorganisms and organisms in which genetic material has been purposely altered through genetic engineering in a way that does not occur naturally. http://www.biotechmedia.com/definitions-g.html#GMO

Germination : The process of causing the initiation of a plant from seed. A seed will germinate, or sprout, when conditions are right for survival. These conditions include: adequate moisture, heat, and/or light. The germinating seed sends its first root (radicle) into the soil and the first stem with the first leaves (cotyledon) toward the sun. Some seeds require pretreatment, such as scarring or soaking, before they will germinate.

Gleaning : Literally meaning, "to collect grain by leapers", gleaning has come to be known as the collective redistribution of food, especially potentially wasted food.

Glucose : A product of photosynthesis and an important source of physiological energy for plants and animals. Glucose is a sugar, or carbohydrate.

Glycolysis : An ATP-generating metabolic process that occurs in nearly all living cells in which glucose is converted in a series of steps to pyruvic acid. The metabolic breakdown of glucose and other sugars that releases energy in the form of ATP.

Gravitropism : Gravitropism is a plant growth response to gravity. Plant shoots display negative gravitropism. When placed on its side, a plant shoot will grow up. Roots display positive gravitropism, they grow down.

Green manure : Crops grown for fertilization, not production. Green Manure's are traditionally crops that are grown to turn into the soil, mostly for a nitrogen source. Word has become interchangeable with cover crops.

Greensand : Greensand is mined from ancient seabeds; it is a dry organic fertilizer. It is useful for its ability to slowly supply to the soil a number of different micronutrients, as well as potassium.

Grounded : A large conducting body, such as the earth or an electric circuit connected to the earth, used as an arbitrary zero of potential. A conducting object, such as a wire, that is connected to such a position of zero potential.

Guard cells : The Guard cells control the stomatal openings in the epidermis of the leaf. Three environmental factors regulate these cells. These factors are light, CO₂ concentration and water availability. When the guard cells are activated, K⁺ pumps actively transport K+ into the guard cells, resulting in a high [K⁺] in the cells. As a result, water enters the cells by osmosis. This causes the guard cells to swell. The one side of the guard cells is thicker than the other and does not stretch. As the guard cells swell up they bend. When the stoma is open CO₂ can diffuse into the leaf and enter the Calvin Cycle. The oxygen produced in photolysis, diffuses out of the open stoma. Water vapor also escapes from the stoma by the process of transpiration. As water transpires, other water molecules are pulled up through the plant behind it.

Gymnosperms : non-flowering plants

Gypsum : Gypsum, which occurs naturally in sedimentary rocks, is a dry organic fertilizer that supplies two important micronutrients: calcium and sulfur.

Hardpan : Although hardpans can occur naturally, they are often caused by repeated compaction of soil particles (such as with the tires of heavy equipment). Soils particularly prone to hardpan are usually heavy in clay. A hardpan will prevent adequate drainage and, depending on its depth, it may stunt or cause malformed root growth. Correct hardpans by double digging, aerating it with a broadfork or spading fork, or for bigger projects, a tiller may be needed.

Hermaphrodite : An individual having the reproductive organs and many of the secondary sex characteristics of both sexes.

HID : High Intensity Discharge.

Hormone : Chemical substance that controls the growth and development of a plant. A substance produced by one tissue and conveyed by the bloodstream to another to effect physiological activity or regulate development, such as growth or metabolism. Acts as a signal.

Humus : The end result of successful composting is humus. It is the rich, dark, and fine mixture of decomposed organic materials. Humus contains the microorganisms necessary for healthy soil, as well as a ready supply of the macro- and micro-nutrients necessary for healthy plants. It also helps create ideal soil tilth through water retention and particle spacing. Use humus in the garden to condition and amend soil. Mix it with the soil for general improvement or use it to side-dress hungry plants.

Hybrid : An offspring created by combining two plants of different breeds, variety, or genetic makeup.

Hydrogen bond : A chemical bond in which a hydrogen atom of one molecule is attracted to an electronegative atom, especially a nitrogen, oxygen, or flourine atom, usually of another molecule.

Hygrometer : Instrument used to measure the relative humidity in the atmosphere.

Hyphae : A single tubular filament of a fungus or any of the thread like parts making up the mycelium of a fungus.

Imbibition : Imbibition will trigger a seed to germinate. It is the absorption of water by the seed, which causes its tissues to swell and for the seed's casing to eventually split. Once the seed has split open the radicle can begin its search of anchorage, water, and nutrients.

Indeterminate growth : Having a capacity for continuing to grow at the apex.

Indigenous : Existing or growing naturally in a region or country.

Inductive reasoning : Reasoning from detailed facts to general principles. Opposite of deductive reasoning.

Inoculate : To bring one organism or material into contact with a host plant or plant organ or t o put or implant microorganisms or anything beneficial to plant growth into soil to stimulate growth, fix nitrogen, etc.

Integrated Pest Management (IPM): IPM is an ecologically based approach to pest (animal and weed) control that utilizes a multi-disciplinary knowledge of crop/pest relationships, establishment of acceptable economic thresholds for pest populations and constant field monitoring for potential problems. Management may include such practices as the use of resistant varieties; crop rotation; cultural practices; optimal use of biological control organisms; certified seed; protective seed treatments; disease-free transplants or rootstock; timeliness of crop cultivation; improved timing of pesticide applications; and removal or 'plow down' of infested plant material.

IPM/NDR: Foods sold with claims of reduced pesticide use or use of integrated pest management (IPM), sometimes certified as containing no detectable residues (NDR).

Ions : Atoms that carry an electric charge, either positive or negative. If an atom gains an electron it takes on a negative charge. If the atom loses an electron it takes on a positive charge. Ex. Table salt = NaCl, dissolved in water is Na+ and Cl-, hence ions. The same idea is applied to salts that break out into relavent nutrient spectrums for plant growth in synthetic fertilizers.

Kelp meal : Kelp meal is used as a dry organic fertilizer. It is rich in micronutrients and plant growth hormones. It is also an excellent source of potassium, of which it is about 18%.

Kilowatt-hour (KWH): a power demand of 1,000 watts for one hour. Power company utility rates are typically expressed in cents per kilowatt-hour.

Larvae : A young insect that hatches from the egg and differs fundamentally in form from the adult. A maggot, the larval stage of a fly, is a good example of this difference.

Leaching : T he process by which soluble materials in the soil, such as salts, nutrients, pesticide chemicals or contaminants, are washed into a lower layer of soil or are dissolved and carried away by water.

Legumes: Legumes are plants that can fix nitrogen from the air to make nitrates. Nitrate is nitrogen in a form available to plants. Legumes, through pinkish colored nodules on their roots, form a mutually beneficial relationship with soilborne bacteria. It the bacteria who are able to perform the chemistry necessary for nitrogen fixation; the plant pulls the nitrogen from the air through stomata in its leaves and transfers it to the bacteria via its phloem. In return, the legume and the plants nearby are supplied with the nitrates. However, if legumes are fed nitrogen (in the form of fertilizer or manure), they will cease to produce their own. Legumes are heavy feeders of phosphorus, potassium, magnesium, and calcium; so they (or the crops that follow) may need feeding if the soil is deficient in these nutrients. Legumes are used as green manures. Common examples are clover, vetch, soybeans, peas, and alfalfa.

Lenticels : Region of roots that permit gas exchange. Equivalent to stomata in leaf.

Ligands : An atom, ion, or function group that is binded to one or more central atoms or ions. An ion, a molecule, or a molecular group that binds to another chemical entity to form a larger complex.

Light reaction : The photosynthetic process in which solar energy is harvested and transferred into the chemical bonds of ATP; can occur only in light.

Lime : When calcium carbonate is finely ground it is called lime. Ground lime is readily dissolved into the soil where it reduces soil acidity by releasing calcium cations. Can also be used to combat maggots in worm bins or compost piles.

Lipids : Diverse class compounds, including fats, oils, fatty acids, triglycerides and steroids essential for membrane formation, energy stores, and fuel molecules.

Loam : Loam soils are comprised of sand, silt, and clay particles. There are both coarse and fine loams. Fine loams have more silt and clay than sand. Coarse loams are mainly sand, which facilitates better drainage, but still contain enough silt and clay to hold moisture and nutrients and thereby support soil organisms. For this reason, coarse loams are considered some of the best soils to cultivate, with fine loams not far behind

Local Food Systems : A collaborative effort to integrate agricultural production with food distribution to enhance the economic, environmental, and social well being of a particular place. This approach supports a food system that preserves local farmland and fosters community economic viability, requires less energy for transportation, and offers consumers the freshest foods.

Lumen : A lumen is the unit that expresses the total quantity of light given of by a source as seen by the human eye, regardless of direction. A lumen is defined as the amount of light falling on a surface of one square foot, every point of which is one foot away from a source, (a section of the inside surface of a sphere) of one candlepower. A uniform source of one candlepower placed in a sphere emits 12.57 lumens.

Macronutrients : Mineral elements required by plants in large amounts- nitrogen, phosphorous, potassium, oxygen, hydrogen, carbon, sulfur, magnesium, and calcium.

Malthus, Thomas : " An Essay on the Principle of Population" was first published in 1798. This important essay first identified the geometric role of natural population increase in outrunning subsistence food supplies, prompting Charles Darwin to explore the actual patterns of evolution. What "struck" Darwin in Essay on the Principle of Population (1798) was Malthus's observation that in nature plants and animals produce far more offspring than can survive, and that Man too is capable of overproducing if left unchecked. Malthus concluded that unless family size was regulated, man's misery of famine would become globally epidemic and eventually consume Man. Malthus' view that poverty and famine were natural outcomes of population growth and food supply was not popular among social reformers who believed that with proper social structures, all ills of man could be eradicated. This sentiment is similar to that of the Agricultural revolution in that Nature could be manipulated with no dire repercussions.

Manure : Nitrogen feeds the microorganisms in soil that make humus from a compost pile. Manure is rich in nitrogen (especially chicken, goat, and steer manures), and is thus a valuable component of compost. It is also rich in potassium and phosphorus. Manure should be composted (or at least aged) before use in the garden because of its high nitrogen --and ammonia-- content, which can both easily burn plants. Composting will also kill any weed seeds that may have survived the animal's stomach(s).

Meristem : Group of undifferentiated cells from which new tissues are produced, and one of the most basic forms of plant tissue. Most plants have apical meristems which give rise to the primary tissues of plants, and some have secondary meristems that add wood or bark. Similar to stem cells in animals. Meristem cells can divide, whereas mature, differentiated cells are specialized in structure and function and usually do not divide. Continued divisions of meristem cells keeps a plant growing throughout it's life = indeterminate growth.

Metabolism : The chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. In metabolism some substances are broken down to yield energy for vital processes while other substances, necessary for life, are synthesized.

Micronutrients : Elements which are required in very small or trace amounts- iron, chlorine, copper, manganese, zinc, molybdenum, and boron.

Microorganism : An organism of microscopic or submicroscopic size, especially a bacterium or protozoan.

Mineral : A naturally occurring, homogeneous inorganic solid substance having a definite chemical composition and characteristic crystalline structure, color, and hardness.

Mineralizaton : Process carried out by soil microorganisms whereby nutrients are released in an inorganic form from the decomposition of organic matter.

Mitosis : The process by which a cell divides into two so that the nucleus of each new cell has a full number of chromosomes.

Monocot : One of the two major types of flowering plants; characterized by having a single cotyledon, arranged in threes or multiples of three, and parallel-veined leaves; include grasses, cattails, lilies, and palm trees.

Monoecious : Plants that have both male and female flowers on the same plant. Most plants of production have been breed to be self-fertilizing or monoecious.

Mother plant : A superior plant that is kept in the vegetative state in order to take cuttings or clones from. When a mother plant is found it is important to ensure maximum success rate so as not to stress the mother plant with too many cuttings.

Mucigel : The gelatinous material at the surface of roots grown in nonsterile soil. It includes natural and modified plant exudates (more specifically mucilages), bacterial cells, and their metabolic products (e.g., capsules and slimes) as well as colloidal mineral and organic matter from the soil.

Mulch : Most mulches are made from organic materials, some of the best being: hay, grass clippings, fallen leaves (best when shredded), bark chips, and compost. Mulching serves to prevent moisture loss from soil, protect plants from temperature extremes, control weed growth (weed before laying mulch!), prevent water from splashing onto plant material, and as a slow-release soil amendment.

Mycelium : The mass of interwoven filaments (hyphae) that makes up the vegetative body of a fungus. This is the portion of the fungus that absorbs nutrients.

Mycorrhiza : "Fungus roots" which are symbiotic with the plant roots on which they occur. This mycorrhiza relationship facilitates the sharing of some of the plant's storehouse of organic compounds (which are essential to fungi, as they are to all living organisms). In addition, water is exchanged along with the organic compounds for assistance from the fungus in the absorption of nutrients like phosphorus and some other minerals. There are endo- and ectomyccorhizae, the endo- aiding in material uptake, the ecto- forming a rhizosphere protecting the roots from potential pathogens or diseases.

Nature : The material world and its phenomena; the forces and processes that produce and control all the phenomena of the material world.

Necrotic : From Greek nekrosis; localized death of living tissue.

Negative pressure : Pressure less than that of the ambient atmosphere; in a growroom this is experienced when air is removed (or exhausted) from your room. The result is the influx of fresh air from outside the room due to the vacuum created by removing the air.

Nematodes : There are at least 12,000 named species of the small unsegmented worms called nematodes. Within a shovel full of soil there may be a million nematodes. Some species parasitize humans, others animals, some parasitize other nematodes, and still others feed on plant roots. Plants attacked by nematodes suffer stunted growth and sometimes yellowing. Control pest nematodes by improving soil. Humus rich soil supports beneficial nematodes and other soil bacteria. Certain species of nematodes can be purchased as beneficials and will help control insect populations by feeding on insect larvae.

Nicotine adenine dinucleotide phosphate (NADP⁺): A substance to which electrons are transferred from photosystem I during photosynthesis; the addition of the electrons reduces NADP, which acquires a hydrogen ion to form NADPH, which is a storage form of energy that can be transferred to the Calvin Cycle for the production of carbohydrate.

Nitrogen fixation: The incorporation of atmospheric nitrogen into nitrogen compounds that are available for uptake by green plants. A process that can be carried out only by certain microorganisms or by higher plants in symbiotic association with microorganisms.

Node : The region of a stem between two internodes, where there is branching of the vascular tissue into leaves or other appendages.

NPK: Symbol for Nitrogen, Phosphorous, and Potassium. Universal to all fertilizers; denotes the three macronutrients or nutrients used most by plants from fertilizers.

Occam's Razor : The principle states that one should not make more assumptions than the minimum needed. It underlies all scientific modeling and theory building. It admonishes us to choose from a set of otherwise equivalent models of a given phenomenon the simplest one. In any given model, Occam's razor helps us to "shave off" those concepts, variables, or constructs that are not really needed to explain the phenomenon. By doing that, developing the model will become much easier, and there is less chance of introducing inconsistencies, ambiguities, and redundancies.

Ohms : A unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals.

Ohm's law : The law stating that the direct current flowing in a conductor is directly proportional to the potential difference between its ends. It is usually formulated as V = IR, where V is the potential difference, or voltage, I is the current, and R is the resistance of the conductor. One ohm is the resistance value through which one volt will maintain a current of one ampere. Recently this formula has been altered to accommodate power (in watts) Power = Volts x Current (amps)

Organic matter : P lant and animal residues, substances made by living organisms, or anything that was once alive. All are based upon carbon compounds.

Organs : Tissues that act together to perform functions. The roots, stems, and leaves are the major organs of plants. All organs are composed of three tissues: epidermis, vascular tissues, and ground tissues.

Osmosis : Water moves from a scenario of high concentration of dissolved solids to a low concentration and is the mechanism by which plants utilize water through their roots.

Ovary : In flowering plants, the part of the flower which encloses the ovules. When the ovary matures, it becomes the fruit.

Oxidation reaction : The combination of a substance with oxygen; a reaction in which the atoms in an element lose electrons and the valence of the element is correspondingly increased. In photosynthesis this means that electrons are removed from oxygen by light energy in order to reconstitute them by way of a reduction reaction to produce ATP and NADPH.

Photosythetically Active Radiation (PAR) : used to refer to the portion of the light spectrum optimal for plant growth, namely about 400 to 700 nanometers in wavelength.

Parenchyma cells : Or ground tissue. Tissues composed of cells within the primary cell wall. The pith of the shoots, the storage tissue of the fruits, the seeds, the roots and other underground organs are all parenchyma tissues.

Parts per Million (PPM): unit used to quantify total dissolved solids (TDS), usually ions, in a nutrient solution. Or a general term to quantify a "part" of one gas or substance relative to "parts" of another substance.

Pathogen : Any organism capable of causing disease.

Peat moss : The partially decomposed remains of mosses harvested commercially from the wild. Though difficult to wet initially, peat moss can absorb up to 25 times its own weight in water and is therefore valued as a an organic soil amendment. Peat moss is acidic --with a pH of about 3 or 4.0-- and should only be used around acid-loving plants or to help lower the pH of alkaline soils. Sphagnum moss is generally recommended over standard peat moss. Note, however, that some sphagnum moss carries a disease causing fungus that you should protect yourself against: wash thoroughly after handling and, especially if you have wounds, consider wearing gloves.

Perennial : Of three or more seasons duration of life.

Perlite : Volcanic ash that has been exposed to very high heat expands to form perlite. It is very light weight and is often used in potting mixes to encourage good drainage, as well as to keep the soil from compacting. Because it is also porous, it helps to maintain soil moisture. Its size ranges, but it is about as large as gravel.

Permeability : T he ability of a material to allow the passage of a liquid, such as water through rocks. Permeable materials, such as gravel and sand, allow water to move quickly through them, whereas impermeable material, such as clay, won't allow water to flow freely.

Peptide bond : The chemical bond formed between the carboxyl groups and amino groups of neighboring amino acids, constituting the primary linkage of all protein structures.

Pericycle : A plant tissue characteristic of the roots, located between the endodermis and vascular tissue.

Petiole : A leaf has two main parts: the blade and the petiole, or stalk.

PH : A measure of the relative acidity or alkalinity of water. Water with a pH of 7 is neutral; lower pH levels indicate increasing acidity, while pH levels higher than 7 indicate increasingly basic solutions.

Phloem : Inner bark tissue responsible for translocation of foodstuffs (e.g. sugars and starches) produced by green tissue to the roots and other parts of the plant. The food conducting tissue in plants. The phloem circulates the products of the leaves, which include sugar, down to the roots. Compare with xylem.

Photoperiod : the relationship between the length of light and dark in a 24-hour period.

Photophosphorylation : The chemical attachment of phosphorous to a molecule, usually associated with the storage of energy in the covalent bond that is also formed. Example: attachment of the third phosphate group to ADP in the formation of the higher energy form, ATP. Photophosphorylation is a type of phosphorylation associated with the formation of ATP in the photosynthesis process.

Photsythates : Food products (sugars and starches) created through photosynthesis.

Photosythesis : The process by which carbon dioxide and water are combined in the presence of light energy and chlorophyll to form carbohydrates. Photosynthesis takes place in the plant cell's chloroplasts. Inside the chloroplasts, chlorophyll absorb light energy from the sun. The chloroplasts then use that energy to jumpstart the process of photosynthesis. The carbohydrates/ sugars are the plant's internal energy storehouse; they are used to build and maintain plant tissue.

Photosythetically Active Radiation : (PAR) portion of the wavelength spectrum beneficial to plant growth. To be compared with lumens, which is light visible to the human eye.

Phototropism : The tendency of growing plant organs to move or curve under the influence of light.

Physiology : The science of dealing with the functions and vital processes of living organisms.

Pigment : Any coloring matter in the tissues of plants or animals.

Pistil : The seed-bearing organ of a flower consisting of ovary, style and stigma; gynoecium.

Plasmodesmata : Fine strands of cytoplasm that are connections between cells that allow the direct exchange of water. Plasmodesmata also provide an easy route for the movement of ions, small molecules like sugars and amino acids, and even macromolecules like RNA and proteins, between cells.

Pollen : The powder produced by anthers, consisting of pollen grains. The male gametophyte is confined to the pollen grain. Each pollen grain contains two cells: the vegetative cell from which the pollen tube develops and the generative cell which produces sperm.

Pollination : Process of transferring the pollen from its place of production to the place where the egg cell is produced. This may be accomplished by the use of wind, water, insects, birds, bats, or other means. Pollination is usually followed by fertilization, in which sperm are released from the pollen grain to unite with the egg cell.

Polymer : Any of numerous natural and synthetic compounds of usually high molecular weight consisting of up to millions of repeated linked units, each a relatively light and simple molecule.

Polypeptide : A protein; containing many molecules of amino acids, typically between 10 and 100 bonded by peptide bonds.

Positive pressure : The phenomenon experienced when using an intake fan to drive airflow in a growroom. By moving air in, air must move out, resulting in the inability to control your air.

Potash : Broadly, potash describes any material containing potassium. More specifically, though, potash is potassium carbonate derived from wood ashes. The term potash comes from the process of extracting lye from wood ashes in iron pots.

Power : The amount of current multiplied by the voltage level at a given point measured in wattage or watts. The product of applied potential difference and current in a direct-current circuit.

Primary growth : Plant growth occurring at the tips of the plant, i.e. meristems.

Primary structure : The linear sequence of amino acids in a protein.

Progeny : Offspring.

Prokaryote : Comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes.

Propagation : The act of propagating; continuance or multiplication of the kind by generation or successive production; as, the propagation of animals or plants.

Protein : Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur and are composed of one or more chains of amino acids. Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism.

Pupate : Develop into a pupa, of insect larva.

Pyrethrum : natural insecticide made from the blossoms of various chrysanthemums

Pythium : A fungal disease infecting root systems, often in hydroponic systems.

Radical : The initial root formed after seed germination. This primary root produces first-order lateral roots. The primary root eventually becomes the taproot of the plant.

Redox reaction : (oxidation/reduction) A chemical reaction in which an atom or ion loses electrons to another atom or ion.

Reduction reaction : A decrease in positive valence or an increase in negative valence by the gaining of electrons.

Resistance : D etermines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms The opposition of a body or substance to current passing through it, resulting in a change of electrical energy into heat or another form of energy.

Respiration : The oxidative process occurring within living cells by which the chemical energy of organic molecules is released in a series of metabolic steps involving the consumption of oxygen and the liberation of carbon dioxide, water, and energy.

Reverse osmosis : (1) (Desalination) The process of removing salts from water using a membrane. With reverse osmosis, the product water passes through a fine membrane that the salts are unable to pass through, while the salt waste (brine) is removed and disposed. This process differs from electrodialysis, where the salts are extracted from the feedwater by using a membrane with an electrical current to separate the ions. The positive ions go through one membrane, while the negative ions flow through a different membrane, leaving the end product of freshwater. (2) (Water Quality) An advanced method of water or wastewater treatment that relies on a semi-permeable membrane to separate waters from pollutants. An external force is used to reverse the normal osmotic process resulting in the solvent moving from a solution of higher concentration to one of lower concentration.

Rhizosphere : The soil near a living root, usually applied to the zone around tiny fine absorbing roots. The soil zone that surrounds and is influenced by the roots of plants.

Rule of Return : An eternal feature of the natural order. It calls for what is grown to be returned and is based on the presence of humus. The idea being that a forest takes care of itself the same way a field should.

Rust : Rusts are a type of fungal disease that generally requires two separate plant species to survive --each at a different point in its life cycle. Like other fungi, rusts reproduce via spores that are easily carried by wind, water, insects, and animals. The best way of controlling rusts (and other fungal diseases) is by removing and destroying infected plant material immediately. Separating or removing one of the two plant hosts will also be effective.

Sand : Because of the relative large size of sand particles (.05-2.0 mm), sandy soils have trouble holding water and nutrients. They are commonly deficient in calcium and magnesium. Adding humus to sandy soils can help. When mixed with a heavier soil (one that is largely comprised of clay), sand can help provide aeration. Sand is also commonly mixed with seed for broadcasting Saprophyte: An organism that uses dead organic matter as its source of food.

Sclerenchyma cells : Mature sclerenchyma cells are dead and have secondary cell walls thickened with cellulose and usually impregnated with lignin. In contrast to collenchyma, which is pliable, sclerenchyma is elastic. The cell cavity or lumen is very small or it may disappear completely. S clerenchyma is an important supporting tissue in plants, and are responsible for the hardness of seeds and shells.

Secondary growth : Growth in a plant that does not occur at the tips of the stems or roots. Secondary growth produces wood and bark in seed plants and an increase in girth of stems and roots of many other plants. Secondary roots occur in the cambium from the pericycle and are roots emitted from any part of the plant above the radical .

Senescence : Growing old; aging.

Sepals : The outer whorl of a flower and collectively are called the calyx. Sepals often resemble reduced leaves and function in the protection of the bud or may be modified to function more like a petal.

Sexual reproduction : In sexual reproduction, the detached portion, which is always a single cell, called the female germ cell, is acted upon by another portion of living matter, the male germ cell, usually from another organism, and in the fusion of the two (impregnation) a new cell is formed, from the development of which arises a new and unique organism.

Shoot : Usually, the above ground portion of a plant, bearing the leaves. Contrast with root.

Silt : A sedimentary material consisting of very fine particles intermediate in size between sand and clay. Silt falls between sand and clay on a scale of particle size at about .002 to .05 mm across. Silt is fragments of minerals and rock and is thus an inorganic component of soil.

Social justice : Concern for the working conditions and labor standards implemented for workers in the agriculture industry. There is a significant movement internationally whose goal is to link the social, economic and environmental dimensions of sustainable agriculture.

Solute : A substance that is dissolved in another substance, thus forming a solution.

Solution : A mixture of a solvent and a solute. In some solutions, such as sugar water, the substances mix so thoroughly that the solute cannot be seen. But in other solutions, such as water mixed with dye, the solution is visibly changed.

Solvent : A substance that dissolves other substances, thus forming a solution. Water dissolves more substances than any other, and is known as the "universal solvent".

Species : A distinct kind. Any of the groups of related plants or animals that make up a genus.

Spore : A small reproductive body usually consisting of a single cell, capable of giving rise to a new adult individual either immediately or after a period of dormancy. In fungi, the microscopic reproductive unit consisting of one or more cells; it is analogous to the seeds of green plants.

Stamen : The male reproductive part of a flower, the tip of which produces pollen and is called the anther.

Stele or vascular cylinder : This zone inside the endodermis contains specialized tissues responsible for transport of water and mineral elements to the shoot (xylem) and organic nutrients, such as photosythetically-fixed carbon, to the roots (phloem) and is responsible for primary growth. The stele separates the vascular tissue from the cortes.

Stigma : The portion of the pistil that receives pollen. Dense region of pigments found in many photosynthetic protists that are sensitive to light, and thus functions somewhat like a miniature eye.

Stomata : An opening or pore on the upper (i.e. water lilies) and/or lower leaf surface through which gas exchange occurs (i.e. oxygen and carbon dioxide) and moisture vapor moves. The size of this opening of the stomate is controlled by `guard cells'. A similar gaseous exchange site (lenticle) exists on stems and roots.

Stroma : The connective tissue framework of an organ, gland, or other structure, as distinguished from the tissues performing the special function of the organ or part. Site of the dark reaction of photosynthesis.

Style : Structural filament in the pistil, or female reproductive organ, in a flower.

Suberin : Waxy, waterproof chemical in some plant cells, notably cork (in stems) and endodermis cells (in roots).

Surface tension : T he attraction of molecules to each other on a liquid's surface. Thus, a barrier is created between the air and the liquid. Water has a high surface tension- i.e. beading up after washing car, or bugs floating on the surface of a lake. Wetting agents can be used to emulsify this property when using a foliar spray so as to maximize potential by laying it down and ensuring uniform coverage of the leaf.

Symbiotic relationship : A relationship between two entities in which both benefit from the collaboration. An example being mycchoriza and plants. The antithesis of this is a parasitic relationship in which the host is fed upon by the parasitic entity.

Symplast : The cytoplasm of the root cells.

Systemic: A term used in reference to a disease within the plant tissue, not initiated from the external cells. This also refers to materials and compounds that are taken up or absorbed by the plant and designed to fight disease.

Terrestrial: Consisting of land, not water. Living on land.

Thorax : The second or middle region of the body of an arthropod, between the head and the abdomen, in insects bearing the true legs and wings.

Tilth : The state of a soil that makes it suitable to plant growth. Good tilth is a sign of healthy soil structure. While digesting organic material, bacteria secrete gum and slime-like matter in the soil. This works like glue, binding soil particles and humus together to form aggregates. The aggregates are crumb-like and allow for good air circulation and water drainage in the soil. Well-aggregated soil is regarded as having good tilth. The addition of organic material will feed microorganisms and thus improve tilth.

Top dressing : A prepared soil mix added to the turf surface; usually incorporated into the soil by raking or irrigating.

Total Dissolved Solids (TDS): total amount of ions, or solid material, present in a solution relative to water.

Transcription : The process by which messenger RNA is synthesized from a DNA template resulting in the transfer of genetic information from the DNA molecule to the messenger RNA.

Transduction : the action or process of converting something and especially energy or a message into another form

Translation : The process by which messenger RNA directs the amino acid sequence of a growing polypeptide during protein synthesis

Transpiration : Process by which water that is absorbed by plants, usually through the roots, is evaporated into the atmosphere from the plant surface, such as leaf pores. Plants (like the cacti) that evolved in arid climates have developed thick skins and have fewer surfaces (shorter stems and modified leaves) to protect against dehydration due to transpiration.

Trophic level : A group of organisms that occupy the same position in a food chain.

Turgor : The normal distention or rigidity of plant cells, resulting from the pressure exerted from within against the cell walls by the cell contents.

Vascular tissue : The supportive and conductive tissue in plants, consisting of xylem and phloem. Makes up the vascular system, which is the equivalent of a human circulatory system.

Vermicomposting : Composting with worms.

Vermiculite : When mica is exposed to very high heat is "pops" --or expands-- to form vermiculite. Horticultural grade vermiculite is granular and is valued in potting mixes because it is relatively inert, but is porous and can hold water and nutrients well. Vermiculite is generally preferred to the similar substance, perlite.

Viable : Though many seeds can keep for years (some for even hundreds of years), most will remain viable for three of less. Seeds that are no longer viable will not germinate, so it is important to buy seeds from reliable sources and to store them appropriately. Keep seeds cool and dry; be sure also to label them with the date of purchase or collection so they can be used in time.

Virulence : The degree of pathogenicity of a given pathogen.

Voltage : is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts. Household sockets are traditionally run for 120 volts (normal outlet) or 240 volts (stove, washer/dryer, etc.)

Water stress : Phenomenon whereby water leaves the plant by way of osmosis due to too high of a fertilizer or ion concentration outside the root. Normally inside the root is more concentrated resulting in the plants ability to uptake water by way of osmosis.

Watts : A measure of the amount of electricity flowing through a wire

Wetting agent : compound that reduces the droplet size and lowers the surface tension of water, making it lay down on a leaf as opposed to beading up, thereby ensuring uniform coverage and maximum uptake.

Whorl : A ring of leaves or structures pertaining to a plant.

Wick : Part of a passive hydroponic system using a wick suspended in the nutrient solution in order for nutrients to pass up the wick and are absorbed by the medium and roots.

Wilts : Water pumping through plant tissue enables the plant to assume an adequate level of turgidity. Without the water's pressure, as in a drought, the plant will weaken and wilt. Some fungi and bacteria destroy the water conducting tissues (xylem) of a plant, which prevents water --and nutrients-- from reaching stems and leaves. Unlike wilting due to minor water stress, the damage caused by fungi and bacteria is permanent. To control, remove and destroy infected plant material.

Worm castings : As an earthworm tunnels through the soil, it digests organic material and excretes it in the form of castings rich in minerals. Castings are a rich soil amendment containing nutrients in a form usable to plants. Over the coarse of a single day, an earthworm will produce castings equal to its own weight.

Xylem : The principal strengthening and water/nutrient conducting tissue of branches, stems and roots. Primarily, the water conducting tissue in plants, though it also carries dissolved nutrients. The xylem pumps the water from the roots into the stem and leaves of the plant. Compare with phloem. Xylem is dead at maturity.

Zeolite : Any one of a family of hydrous aluminum silicate minerals, whose molecules enclose cations of sodium, potassium, calcium, strontium, or barium, or a corresponding synthetic compound, used chiefly as molecular filters and ion-exchange agents.

Zygote : A cell formed by the union of male and female gametes.