Key Terms
Acid Soil: Soil that has a pH value of less than 5.5 for most of the year.
Adventitious Root System: Roots that form from non-root tissue. In contrast to taproots, adventitious root systems (or fibrous root systems) have networks of many small roots instead of one large main root with a few side roots.
Aeration: To supply with air.
Aggregate Fruit: A fruit that develops from the merger of several ovaries that were separated in a single flower.
Aggregates: A material or structure formed from a loosely compacted mass of fragments or particles.
Agriculture: The science or practice of farming, including cultivation of soil for the growing of crops and the rearing of animals to provide food, wool, and other products.
Air: The invisible gaseous substance surrounding the earth; mixture of mainly oxygen and nitrogen.
Alternate Attachment Pattern: A leaf attachment pattern in which the leaves are single at each node and borne along the stem alternately in an ascending spiral.
Ammonium Nitrate: A white crystalline solid used as a fertilizer and as a content of some explosives.
Androecium: The aggregate of stamens in the flower of a seed plant.
Angiosperm: Plants that produce their seeds in fruits and produce flowers, representing 80% of all known living green plants.
Anther: The part of a stamen that contains pollen.
Axillary Bud: A bud that grows from the axil of a leaf, developing into a branch or flower cluster.
Apex: The tip or protruding part of a leaf.
Apomoxis: Asexual reproduction in plants.
Asexual Reproduction: A mode of reproduction in which new offspring is produced by a single parent.
Axillary Inflorescence: An inflorescence that arises from a leaf axil.
Base: The slightly expanded area of a leaf where the leaf attaches to the stem or petiole.
Blade: Also known as the lamina, the leaf blade is the expanded thin and green part of a leaf; it performs photosynthesis.
Boron: A chemical element; a non-metallic solid found in soil.
Botany: A branch of biology that is concerned with the scientific study of plants, including their physiology, structure, genetics, ecology, distribution, classification and economic importance.
Biochemistry: The branch of science concerned with the chemical and physicochemical processes and substances that occur within living organisms.
Biodiversity: The variety of life in the world or or in a particular habitat or ecosystem.
Biology: The study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution.
Bloom: A flower, particularly one cultivated for its beauty. Also, a delicate, powdery substance on the surface of certain fresh fruits, leaves, or stems.
Blossom: A flower or mass of flowers, especially on a tree or bush.
Botanical Nomenclature: The formal, scientific naming of plants. Related to, but distinct from, taxonomy.
Bracts: A modified leaf or scale with a flower or flower cluster in its axil. They can sometimes be larger and more brightly colored than a plant's true flower.
Bud: A compact growth on a plant that develops into a leaf, flower or stem.
Calcium: A soft grey metal found in soil.
Calyx: The sepals of a flower, typically forming a whorl that encloses the petals and forms a protective layer around a flower in a bud.
Cambium: A cellular plant tissue from which phloem, xylem, or cork grows by division, resulting in secondary thickening.
Capitulum: A compact head of a structure, in particular a dense flat cluster of small flowers or florets.
Carbohydrates: A group of organic compounds that include sugars, starch and cellulose and that contain hydrogen and oxygen in the same ratio as water.
Carbon: A nonmetallic element found more or less pure in nature or as a part of coal and petroleum and of the bodies of living things or obtained artificially.
Carbon Dioxide: A colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It is naturally present in air and is absorbed by plants in photosynthesis.
Catkin: A flowering spike that is typically downy, pendulous, composed of flowers of a single sex, and wind-pollinated.
Central Vein: Also known as the midvein, the central vein is the main vein running down the center of a leaf, from which secondary veins originate.
Chlorine: A pale green gas found in soil.
Chlorophyll: A green pigment present in all green plants responsible for the absorption of light to provide energy for photosynthesis.
Chloroplast: A plastid that contains chlorophyll and in which photosynthesis takes place.
Clasping Attachment: Also called amplexicaul attachment, a sessile leaf with the base partly or entirely surrounding the stem.
Clay Soil: A soil that contains a high percentage of fine particles and colloidal substance and becomes sticky when wet.
Cobalt: A hard, silvery-white magnetic metal found in soil.
Collective Fruit: Also called a Multiple Fruit; a fruit that forms from a mass of flowers.
Complete Fertilizer: A fertilizer that contains all three primary nutrients (nitrogen, phosphorus, and potassium).
Compost: Decayed organic material used as soil fertilizer.
Compound Leaf: A leaf of a plant consisting of several or many distinct parts, also called leaflets, joined to a single stem.
Connate Perfoliate Attachment: A variety of sessile leaf attachment where the bases of opposite leaves are fused around the stem.
Copper: A reddish-brown metal found in soil.
Corm: A rounded underground storage organ present in plants that consists of a swollen stem base covered with scale leaves.
Corolla: The petals of a flower, typically forming a whorl within the sepals and enclosing the reproductive organs.
Cortex: A band of tissue in a stem or root between the bark and vascular tissue.
Cotyledon: An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.
Cross-Pollination: Pollination of a flower or plant with pollen from another flower or plant
Cultivar: A plant variety that has been produced in cultivation by selective breeding. The cultivar of a plant is usually italicized and in single quotations.
Cuticle: A protective and waxy or hard layer covering the epidermis of a plant, invertebrate, or shell.
Deciduous: A plant descriptor that indicates that a plant loses its leaves seasonally.
Decomposition: The state or process of rotting.
Dicotyledon: A flowering plant with an embryo that bears two cotyledons (or seed leaves).
Dirt: Loose soil or earth.
Double Serrated Margins: A leaf margin type having large primary serrated sections that are also serrated along their edges.
Doubly Compound: Also called bipinnately compound; Leaves that are twice divided, with leaflets arranged along the secondary veins.
Egg: The female reproductive cell in plants; an ovum.
Egg Nucleus: The heart of an egg cell, containing most of the genetic information of the cell.
Elliptical: A simple leaf shaped like an ellipse (widest in the center and pointed at both ends).
Endosperm: The part of a seed which acts as a food store for the developing plant embryo, usually containing starch with protein and other nutrients.
Endosperm Nucleus: The triploid nucleus formed formed in the embryo sac of a seed plant by fusion of a sperm nucleus with two polar nuclei or with a nucleus formed by the prior fusion of the polar nuclei.
Entire Margined: A description of a leaf margin that is smooth-edged.
Epicotyl: The region of an embryo or seedling stem that is above the cotyledon.
Epidermis: The outermost cells of a stem covering the stem, roots, leaf, flower, fruit and seed that provides a protective barrier against injury, water loss and infection.
Evergreen: Relating to or denoting a plant that retains its green leaves throughout the year.
Fertilization: The action or process of fertilizing an egg, involving the fusion of male and female gametes to form a zygote.
Fertilizer: A chemical or natural substance added to soil or land to increase its fertility. There are many types of fertilizer, including natural, natural inorganic, liquid, and solid.
Fibrous Roots: Roots that form from non-root tissue. In contrast to taproots, fibrous root systems (or adventitious root systems) have networks of many small roots instead of one large main root with a few side roots.
Filament: The thin stalk that supports the anther in the male portion of the flower.
Fish Emulsion: A fertilizer emulsion produced from the fluid remains of fish processed for fish oil and fish meal industrially.
Flower: The seed-bearing part of a plant, consisting of reproductive organs that are typically surrounded by a brightly colored corolla and a calyx.
Foliage: The leaves on a plant, collectively.
Forestry: The science or practice of planting, managing and caring for forests.
Frond: The leaf or leaflike part of a palm or fern.
Fruit: A mature, ripened ovary, along with the contents of the ovary.
Genus: A principal taxonomic category that ranks above species and below family, and is denoted by a capitalized name.
Glucose: A simple sugar which is an important energy source in organisms and is a component of many carbohydrates.
Guard Cell: Each of a pair of curved cells that surround a stoma, becoming larger or smaller according to the pressure within the cells
Gymnosperm: A plant with seeds that are not enclosed within a fruit.
Gynoecium: The female part of a flower.
Heavy Soil: A soil rich in fine clay particles; considered difficult to manage but rich in nutrients.
Horizon A: A surface horizon of soil that may be darker in color than the other layers and contain organic matter; this is the horizon in which the most biological activity occurs.
Horizon B: A soil horizon below horizons O, A, and E in which all or most of the original parent structures or bedding features have been obliterated.
Horizon C: A mineral horizon above the bedrock level.
Horizon E: A mineral horizon in the upper part of the soil, typically only present in forested areas; it is light in color and usually leached of nutrients due to rainfall and irrigation.
Horizon O: A horizon above the soil surface which contains much organic material in varying stages of decomposition.
Horticulture: The art or practice of garden cultivation and management.
Humidity: A quantity representing the amount of water vapor in the atmosphere or in a gas.
Humus: The organic component of soil formed by the decomposition of leaves and other plant material by soil microorganisms.
Hydrogen: A colorless, odorless, highly flammable gas present in soil.
Hyphae: Also called fungal hyphae; the branching filaments that make up the mycelium of a fungus.
Hypocotyl: The part of the stem of an embryo plant beneath the stalks of the seed leaves or cotyledons and directly above the root.
Imperfect Flower: A flower that does not have both male and female structures.
Inflorescence: The complete flower head of a plant including stems, stalks, bracts and flowers.
Iron: A strong, hard, magnetic silvery-grey metal found in soil.
Lamina: A thin layer of organic tissue.
Lanceolate: A leaf, sepal, petal or other flat structure that is wider at the base than at the midpoint, that tapers toward the apex, and has a length-to-width ratio of 3:1 or more.
Leaf: A flattened structure on a plant that is typically green and blade-like and attached to a stem directly or via stalk. They are the main organs of photosynthesis and transpiration.
Leaf Bud: A bud on a plant from which a leaf develops.
Leaf Scar: The mark left by a leaf after it falls or is removed from a plant.
Leaf Stalk: A petiole; the stem of a leaf that attaches to the main stem of a plant.
Lenticel: A raised pore on the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues.
Light Soil: A soil that is high in sand content; considered very easy to work with and one that drains very well.
Linear: A type of leaf shape that is long and slender.
Liquid Kelp: A fertilizer derived from organic seaweed.
Loam: A fertile soil of clay and sand containing humus.
Macronutrients: Soil elements which plants require in large amounts to grow well.
Magnesium: An alkaline, silver-white metal that is found in soil.
Manganese: A hard grey metal that is found in soil.
Manure: Animal dung used for fertilizing land.
Margin: The edge of a leaf.
Midrib: The central vein or ridge of a leaf or leaflike part of a plant.
Micronutrients: Soil elements which plants require in small amounts to grow well.
Microorganisms: A microscopic organism found in soil, especially a bacteria or fungus.
Midvein: Also known as the central vein, the midvein is the main vein running down the center of a leaf, from which secondary veins originate.
Mineral: A solid, inorganic substance of natural occurrence found in soil.
Modified Stem: Either above- or below-ground (or aerial) stems that have evolved to enable plants to survive in particular habitats and environments.
Molybdenum: A brittle silver-grey metal found in soil.
Monocotyledon: A flowering plant that bears a single seed leaf (cotyledon).
Multiple Fruit: Also called a Collective Fruit; a fruit that forms from a mass of flowers.
Nectar: A sugary fluid secreted by plants, especially within flowers to encourage pollination by insects and other animals. This is what is collected by bees to create honey.
Net Veined: Having veins that branch and come together again to form a network.
Neutral Soil: A soil with a pH level of 7.0.
Nickel: A silvery-white metal found in soil.
Nitrogen: A colorless, odorless, unreactive gas that forms around 78% of the earth's atmosphere and is also found in soil.
Node: Small bumps or areas of swelling where new leaves or stems emerge from a plant.
Opposite Attachment Pattern: A leaf attachment pattern on a plant where the leaves are paired at a node and borne on opposite sides of the stem.
Organic Matter: Matter composed of organic compounds that have come from the feces and remains of organisms such as plants and animals.
Ovary: A female reproductive organ in which ova or eggs are produced; the hollow base of the carpel of a flower, containing one or more ovules.
Ovate: A leaf or petal whose shape is wider at the base than at the midpoint, that tapers toward the apex, and has a length-to-width ratio of 1.5:1 to less than 2:1.
Ovules: The part of the ovary of seed plants that contains the female germ cell and after fertilization becomes the seed.
Oxidation: A chemical reaction that that takes place when a substance comes into contact with oxygen or another oxidizing substance.
Oxygen: A colorless, odorless reactive gas that forms about 21% of the atmosphere.
Palisade Mesophyll: One or more layers of cells located directly under the epidermal cells of the adaxial leaf blade surface.
Palmate Venation: A leaf venation type in which the main veins of the blade radiate from a common point at the base of the leaf.
Palmately Compound: A type of compound leaf in which all leaflets originate from a central common point at the base of the compound leaf.
Palmately Lobed Margins: A type of lobed leaf margins in which the lobes all radiate out from a central common point at the base of the leaf.
Panicle: A loose branching cluster of flowers.
Parallel Veined: Having veins that are arranged nearly parallel to one another and do not branch and come together again.
Parent Material: Disintegrated rock material usually unconsolidated and unchanged or only slightly changed; the underlying geological material from which soil horizons form.
Peat: A brown deposit resembling soil, formed by the decomposition of vegetable matter in the wet acidic conditions of bogs and fens, often used as a soil amendment.
Peduncle: The stalk bearing a flower or fruit, or the main stalk of an inflorescence.
Perfect Flower: A flower that has male and female structures in one flower.
Perfoliate Attachment: A leaf attachment pattern where the stem appears to grow through a leaf.
Petal: Each of the segments of the corolla of a flower, which are modified leaves and are usually colored.
Petiolate Attachment: A leaf attachment pattern in which a leaf is attached to the stem of a plant via a smaller leafstalk, or petiole.
Petiole: A leafstalk, or smaller stem that connects a leaf to a plant's stem.
Phloem: The living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis.
Phosphorus: A poisonous, combustible metal present in soil.
Photosynthesis: The process by which green plants use sunlight to synthesize foods from carbon dioxide and water.
Pinna: A leaflet on a secondary vein in a compound leaf structure.
Pinnately Compound: A leaf which is divided into smaller leaflets, which are arranged on each side of a leaf's central stalk.
Pinnate Venation: A type of venation pattern in which the secondary veins run parallel to each other from the midrib toward the margin.
Pinnately Lobed Margins: A leaf whose lobes are arranged on either side of a central axis, like a feather.
Pinnule: A leaflet on a compound leaf, comprised of pinnas.
Pistil: The female organ of a flower, comprised of a stigma, style, and ovary.
Pith: A continuous central strand of spongy tissue in the stems of most vascular plants.
Polar Nuclei: Two nuclei that migrate toward the center of the embryo sac and fuse with a male nucleus (sperm) to form the primary endosperm nucleus which divides and sometimes forms the endosperm.
Pollen Grain: Microscopic particles, typically single-celled, of which pollen is comprised. They have a tough coat.
Pollen Sac: One of the pouches of a seed plant anther in which pollen is found.
Pollen Tube: The hollow tube that develops from a pollen grain when deposited on the stigma of of a flower. It penetrates the style and conveys the male gametes to the ovule.
Pollination: The transfer of pollen to a stigma, ovule, flower or plant to allow fertilization.
Pollinator: An insect or other agent or animal that conveys pollen to a plant and so allows fertilization.
Pore Space: The porosity of soil; the space between mineral grains in soil, formed from varying parts water and air.
Potassium: A soft, silvery-white reactive alkali metal found in soil.
Raceme: A flower cluster with the separate flowers attached by short equal stalks at equal distances along a central stem; the flowers at the base of which open first.
Receptacle: The part of a flower stalk where the parts of the flower are attached.
Respiration: A process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.
Reticulated: Net-veined.
Rhizome: A continuously growing underground stem that puts out lateral shoots and adventitious roots at intervals.
Rock: A natural substance composed of solid crystals of different minerals that have been fused together into a solid lump.
Roots: The part of a plant which attaches it to the ground or to a support, typically under the soil surface that also convey water and nourishment to the rest of the plant via numerous branches and fibers.
Runner: A slender stem that grows horizontally along the ground, giving rise to roots and vertical stems and branches at nodes.
Saline Soil: Soil that contains enough soluble salts to interfere with the ability of plants to take up water.
Sandy Soil: A soil containing more than 85% sand-sized particles by mass.
Scale Leaves: Small modified leaves that are usually colorless, though they can be green. They are found most commonly on conifers.
Scalloped Margins: A type of leaf margin that has rounded scallops.
Secondary Veins: The second thickest veins on a leaf that arise from the midrib, or central vein.
Seed: A flowering plant's unit of reproduction, capable of developing into another such plant.
Seed Coat: The protective outer coat of a seed.
Seedling: A young plant, especially one raised from seed and not from a cutting.
Self-Pollination: The pollination of a flower by pollen from the same flower or from another flower on the same plant.
Sepals: Each of the parts of a calyx of a flower, enclosing the petals and typically green and leaflike.
Serrated Margins: Leaf margins that are toothed and saw-like.
Sessile Attachment: A leaf attachment pattern that indicates a leaf directly attached to a stem.
Sexual Reproduction: The production of new living organisms by combining genetic information from two individuals of differing sexes.
Sheath Leaf: A leaf whose lower portion encircles the stem.
Sheathing Attachment: A type of leaf attachment with a tubular portion of the leaf blade surrounding the stem below the base.
Shoot Apex: The growing tip of the plant shoot in which all cells are capable of repeated division.
Silt: Fine sand, clay or other material carried by running water and deposited as a sediment, especially in a channel or harbor.
Simple Fruit: One that develops from a single ovary.
Simple Leaf: A leaf whose blade is not divided to the midrib, though it can be lobed.
Single Flower: A flower in which a single row of petals is arranged around the center of the flower head.
Sodium: A soft silver-white alkali reactive metal found in soil.
Soil Composition: The nutrients and various other materials and substances present in a sample of soil.
Soil Profile: A vertical succession of horizons in a local soil.
Soil Reaction (pH): The degree of soil acidity or alkalinity.
Soil Structure: The way individual particles of sand, silt, and clay are assembled in a soil.
Soil Surface: The immediate uppermost loose layer of the earth containing organic matter and soil organisms suitable for plant growth.
Soil Texture: A summation of the proportions of sand, silt, and clay content in a soil sample.
Soil Type: A classification of soil based on its percentages of clay, silt and sand.
Spadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe.
Spathe: A large, sheathing bract enclosing the flower cluster of certain plants.
Species: A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. It is a taxonomic unit that ranks below genus.
Sperm: The male sex cell of a plant.
Spike: An unbranched, indeterminate inflorescence, bearing sessile flowers.
Spine: A firm, slender, sharp-pointed structure that is a modified leaf.
Spined Margins: A type of leaf margin that has sharp points.
Spongy Mesophyll: A complex, porous tissue found in plant leaves that enables carbon capture and provides mechanical stability.
Stamen: The male fertilizing organ of a flower, typically consisting of a pollen-containing anther and a filament.
Stem: A main structural part of a vascular plant that bears buds, shoots, and leaves.
Stigma: The part of the pistil where pollen germinates.
Stipule: A small, leaflike appendage to a leaf that is typically borne in pairs at the base of a leaf stalk.
Stolon: A creeping horizontal plant stem or runner that takes roots at points along its length to form new plants.
Stoma: (plural: stomata) A minute pore in the epidermis of the leaf or stem of a plant which allows movement of gases in and out of cellular spaces.
Storage Leaves: Thick leaves that can be found either above or below the soil surface, as in those of an onion or a succulent plant.
Style: A structure found within a flower that is a slender stalk connecting the stigma and the ovary.
Subsoil: The layer of earth immediately below the surface soil, consisting predominately of minerals and leached materials such as iron and aluminum compounds.
Sulfur: A yellow combustible material found in soil.
Superphosphate: A fertilizer made from treating phosphate rock with sulfuric or phosphoric acid.
Taproot: A straight tapering root that grows vertically downward, forming the center from which subsidiary rootlets form.
Taxonomy: A branch of science concerned with classification of living organisms.
Tendril: A slender threadlike appendage of a climbing plant that grows in a spiraled manner, stretching and twining around structures and support.
Terminal Inflorescence: A type of inflorescence that rises above the leaves of a plant.
Toothed Margins: A type of leaf margins that has small points along it.
Topsoil: The top layer of soil.
Truncate: A leaf shape that ends abruptly, as if cut off at the base or tip.
Transpiration: The exhalation of water vapor through the stomata of the leaves of a plant.
Tuber: A much-thickened underground part of a stem or rhizome.
Turgor Pressure: The pressure exerted by fluid against a cell wall.
Twig: A slender woody shoot that grows from a branch or stem of a tree or shrub.
Umbel: A flower cluster in which stalks of nearly equal lengths spring from a common center and form a flat or curved surface.
Variegation: Exhibiting different colors, especially as irregular patches or streaks.
Vascular Bundle: A strand of conducting vessels in the stem or leaves of plant, typically with phloem on the outside and xylem on the inside.
Vascular System: A network of conducting tissues interconnecting all organs, transporting minerals, water, nutrients, organic compounds, and various signaling molecules.
Vascular Tissue: Complex conducting tissue formed of more than one cell type found in vascular plants.
Venation: The arrangement of veins in a leaf.
Vegetative Bud: A leaf bud; the bud that contains embryonic leaf.
Vegetative Reproduction: A form of asexual reproduction in plants in which multicellular structures become detached from the parent plant and develop into new individuals that are identical to the parent plant.
Vein: Small channels or capillaries that transport water and minerals to and from the leaf of a plant.
Veinlet: A small or secondary vein on the leaf of a plant.
Water: A colorless, transparent, odorless liquid that is the basis of the fluids of living organisms.
Water-Soluble Fertilizer: A fertilizer that can be dissolved in water.
Whorled Attachment Pattern: Three or more equally spaced leaves at a node.
Xylem: Vascular tissue in plants that that conducts water and dissolved nutrients upward from the root and helps form woody elements of stems.
Xylem Vessel: The type of cell found in xylem that conducts water through plants.
Zinc: A silvery-white metal present in soil.
Zygote: A fertilized ovum.
Adventitious Root System: Roots that form from non-root tissue. In contrast to taproots, adventitious root systems (or fibrous root systems) have networks of many small roots instead of one large main root with a few side roots.
Aeration: To supply with air.
Aggregate Fruit: A fruit that develops from the merger of several ovaries that were separated in a single flower.
Aggregates: A material or structure formed from a loosely compacted mass of fragments or particles.
Agriculture: The science or practice of farming, including cultivation of soil for the growing of crops and the rearing of animals to provide food, wool, and other products.
Air: The invisible gaseous substance surrounding the earth; mixture of mainly oxygen and nitrogen.
Alternate Attachment Pattern: A leaf attachment pattern in which the leaves are single at each node and borne along the stem alternately in an ascending spiral.
Ammonium Nitrate: A white crystalline solid used as a fertilizer and as a content of some explosives.
Androecium: The aggregate of stamens in the flower of a seed plant.
Angiosperm: Plants that produce their seeds in fruits and produce flowers, representing 80% of all known living green plants.
Anther: The part of a stamen that contains pollen.
Axillary Bud: A bud that grows from the axil of a leaf, developing into a branch or flower cluster.
Apex: The tip or protruding part of a leaf.
Apomoxis: Asexual reproduction in plants.
Asexual Reproduction: A mode of reproduction in which new offspring is produced by a single parent.
Axillary Inflorescence: An inflorescence that arises from a leaf axil.
Base: The slightly expanded area of a leaf where the leaf attaches to the stem or petiole.
Blade: Also known as the lamina, the leaf blade is the expanded thin and green part of a leaf; it performs photosynthesis.
Boron: A chemical element; a non-metallic solid found in soil.
Botany: A branch of biology that is concerned with the scientific study of plants, including their physiology, structure, genetics, ecology, distribution, classification and economic importance.
Biochemistry: The branch of science concerned with the chemical and physicochemical processes and substances that occur within living organisms.
Biodiversity: The variety of life in the world or or in a particular habitat or ecosystem.
Biology: The study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution.
Bloom: A flower, particularly one cultivated for its beauty. Also, a delicate, powdery substance on the surface of certain fresh fruits, leaves, or stems.
Blossom: A flower or mass of flowers, especially on a tree or bush.
Botanical Nomenclature: The formal, scientific naming of plants. Related to, but distinct from, taxonomy.
Bracts: A modified leaf or scale with a flower or flower cluster in its axil. They can sometimes be larger and more brightly colored than a plant's true flower.
Bud: A compact growth on a plant that develops into a leaf, flower or stem.
Calcium: A soft grey metal found in soil.
Calyx: The sepals of a flower, typically forming a whorl that encloses the petals and forms a protective layer around a flower in a bud.
Cambium: A cellular plant tissue from which phloem, xylem, or cork grows by division, resulting in secondary thickening.
Capitulum: A compact head of a structure, in particular a dense flat cluster of small flowers or florets.
Carbohydrates: A group of organic compounds that include sugars, starch and cellulose and that contain hydrogen and oxygen in the same ratio as water.
Carbon: A nonmetallic element found more or less pure in nature or as a part of coal and petroleum and of the bodies of living things or obtained artificially.
Carbon Dioxide: A colorless, odorless gas produced by burning carbon and organic compounds and by respiration. It is naturally present in air and is absorbed by plants in photosynthesis.
Catkin: A flowering spike that is typically downy, pendulous, composed of flowers of a single sex, and wind-pollinated.
Central Vein: Also known as the midvein, the central vein is the main vein running down the center of a leaf, from which secondary veins originate.
Chlorine: A pale green gas found in soil.
Chlorophyll: A green pigment present in all green plants responsible for the absorption of light to provide energy for photosynthesis.
Chloroplast: A plastid that contains chlorophyll and in which photosynthesis takes place.
Clasping Attachment: Also called amplexicaul attachment, a sessile leaf with the base partly or entirely surrounding the stem.
Clay Soil: A soil that contains a high percentage of fine particles and colloidal substance and becomes sticky when wet.
Cobalt: A hard, silvery-white magnetic metal found in soil.
Collective Fruit: Also called a Multiple Fruit; a fruit that forms from a mass of flowers.
Complete Fertilizer: A fertilizer that contains all three primary nutrients (nitrogen, phosphorus, and potassium).
Compost: Decayed organic material used as soil fertilizer.
Compound Leaf: A leaf of a plant consisting of several or many distinct parts, also called leaflets, joined to a single stem.
Connate Perfoliate Attachment: A variety of sessile leaf attachment where the bases of opposite leaves are fused around the stem.
Copper: A reddish-brown metal found in soil.
Corm: A rounded underground storage organ present in plants that consists of a swollen stem base covered with scale leaves.
Corolla: The petals of a flower, typically forming a whorl within the sepals and enclosing the reproductive organs.
Cortex: A band of tissue in a stem or root between the bark and vascular tissue.
Cotyledon: An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.
Cross-Pollination: Pollination of a flower or plant with pollen from another flower or plant
Cultivar: A plant variety that has been produced in cultivation by selective breeding. The cultivar of a plant is usually italicized and in single quotations.
Cuticle: A protective and waxy or hard layer covering the epidermis of a plant, invertebrate, or shell.
Deciduous: A plant descriptor that indicates that a plant loses its leaves seasonally.
Decomposition: The state or process of rotting.
Dicotyledon: A flowering plant with an embryo that bears two cotyledons (or seed leaves).
Dirt: Loose soil or earth.
Double Serrated Margins: A leaf margin type having large primary serrated sections that are also serrated along their edges.
Doubly Compound: Also called bipinnately compound; Leaves that are twice divided, with leaflets arranged along the secondary veins.
Egg: The female reproductive cell in plants; an ovum.
Egg Nucleus: The heart of an egg cell, containing most of the genetic information of the cell.
Elliptical: A simple leaf shaped like an ellipse (widest in the center and pointed at both ends).
Endosperm: The part of a seed which acts as a food store for the developing plant embryo, usually containing starch with protein and other nutrients.
Endosperm Nucleus: The triploid nucleus formed formed in the embryo sac of a seed plant by fusion of a sperm nucleus with two polar nuclei or with a nucleus formed by the prior fusion of the polar nuclei.
Entire Margined: A description of a leaf margin that is smooth-edged.
Epicotyl: The region of an embryo or seedling stem that is above the cotyledon.
Epidermis: The outermost cells of a stem covering the stem, roots, leaf, flower, fruit and seed that provides a protective barrier against injury, water loss and infection.
Evergreen: Relating to or denoting a plant that retains its green leaves throughout the year.
Fertilization: The action or process of fertilizing an egg, involving the fusion of male and female gametes to form a zygote.
Fertilizer: A chemical or natural substance added to soil or land to increase its fertility. There are many types of fertilizer, including natural, natural inorganic, liquid, and solid.
Fibrous Roots: Roots that form from non-root tissue. In contrast to taproots, fibrous root systems (or adventitious root systems) have networks of many small roots instead of one large main root with a few side roots.
Filament: The thin stalk that supports the anther in the male portion of the flower.
Fish Emulsion: A fertilizer emulsion produced from the fluid remains of fish processed for fish oil and fish meal industrially.
Flower: The seed-bearing part of a plant, consisting of reproductive organs that are typically surrounded by a brightly colored corolla and a calyx.
Foliage: The leaves on a plant, collectively.
Forestry: The science or practice of planting, managing and caring for forests.
Frond: The leaf or leaflike part of a palm or fern.
Fruit: A mature, ripened ovary, along with the contents of the ovary.
Genus: A principal taxonomic category that ranks above species and below family, and is denoted by a capitalized name.
Glucose: A simple sugar which is an important energy source in organisms and is a component of many carbohydrates.
Guard Cell: Each of a pair of curved cells that surround a stoma, becoming larger or smaller according to the pressure within the cells
Gymnosperm: A plant with seeds that are not enclosed within a fruit.
Gynoecium: The female part of a flower.
Heavy Soil: A soil rich in fine clay particles; considered difficult to manage but rich in nutrients.
Horizon A: A surface horizon of soil that may be darker in color than the other layers and contain organic matter; this is the horizon in which the most biological activity occurs.
Horizon B: A soil horizon below horizons O, A, and E in which all or most of the original parent structures or bedding features have been obliterated.
Horizon C: A mineral horizon above the bedrock level.
Horizon E: A mineral horizon in the upper part of the soil, typically only present in forested areas; it is light in color and usually leached of nutrients due to rainfall and irrigation.
Horizon O: A horizon above the soil surface which contains much organic material in varying stages of decomposition.
Horticulture: The art or practice of garden cultivation and management.
Humidity: A quantity representing the amount of water vapor in the atmosphere or in a gas.
Humus: The organic component of soil formed by the decomposition of leaves and other plant material by soil microorganisms.
Hydrogen: A colorless, odorless, highly flammable gas present in soil.
Hyphae: Also called fungal hyphae; the branching filaments that make up the mycelium of a fungus.
Hypocotyl: The part of the stem of an embryo plant beneath the stalks of the seed leaves or cotyledons and directly above the root.
Imperfect Flower: A flower that does not have both male and female structures.
Inflorescence: The complete flower head of a plant including stems, stalks, bracts and flowers.
Iron: A strong, hard, magnetic silvery-grey metal found in soil.
Lamina: A thin layer of organic tissue.
Lanceolate: A leaf, sepal, petal or other flat structure that is wider at the base than at the midpoint, that tapers toward the apex, and has a length-to-width ratio of 3:1 or more.
Leaf: A flattened structure on a plant that is typically green and blade-like and attached to a stem directly or via stalk. They are the main organs of photosynthesis and transpiration.
Leaf Bud: A bud on a plant from which a leaf develops.
Leaf Scar: The mark left by a leaf after it falls or is removed from a plant.
Leaf Stalk: A petiole; the stem of a leaf that attaches to the main stem of a plant.
Lenticel: A raised pore on the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues.
Light Soil: A soil that is high in sand content; considered very easy to work with and one that drains very well.
Linear: A type of leaf shape that is long and slender.
Liquid Kelp: A fertilizer derived from organic seaweed.
Loam: A fertile soil of clay and sand containing humus.
Macronutrients: Soil elements which plants require in large amounts to grow well.
Magnesium: An alkaline, silver-white metal that is found in soil.
Manganese: A hard grey metal that is found in soil.
Manure: Animal dung used for fertilizing land.
Margin: The edge of a leaf.
Midrib: The central vein or ridge of a leaf or leaflike part of a plant.
Micronutrients: Soil elements which plants require in small amounts to grow well.
Microorganisms: A microscopic organism found in soil, especially a bacteria or fungus.
Midvein: Also known as the central vein, the midvein is the main vein running down the center of a leaf, from which secondary veins originate.
Mineral: A solid, inorganic substance of natural occurrence found in soil.
Modified Stem: Either above- or below-ground (or aerial) stems that have evolved to enable plants to survive in particular habitats and environments.
Molybdenum: A brittle silver-grey metal found in soil.
Monocotyledon: A flowering plant that bears a single seed leaf (cotyledon).
Multiple Fruit: Also called a Collective Fruit; a fruit that forms from a mass of flowers.
Nectar: A sugary fluid secreted by plants, especially within flowers to encourage pollination by insects and other animals. This is what is collected by bees to create honey.
Net Veined: Having veins that branch and come together again to form a network.
Neutral Soil: A soil with a pH level of 7.0.
Nickel: A silvery-white metal found in soil.
Nitrogen: A colorless, odorless, unreactive gas that forms around 78% of the earth's atmosphere and is also found in soil.
Node: Small bumps or areas of swelling where new leaves or stems emerge from a plant.
Opposite Attachment Pattern: A leaf attachment pattern on a plant where the leaves are paired at a node and borne on opposite sides of the stem.
Organic Matter: Matter composed of organic compounds that have come from the feces and remains of organisms such as plants and animals.
Ovary: A female reproductive organ in which ova or eggs are produced; the hollow base of the carpel of a flower, containing one or more ovules.
Ovate: A leaf or petal whose shape is wider at the base than at the midpoint, that tapers toward the apex, and has a length-to-width ratio of 1.5:1 to less than 2:1.
Ovules: The part of the ovary of seed plants that contains the female germ cell and after fertilization becomes the seed.
Oxidation: A chemical reaction that that takes place when a substance comes into contact with oxygen or another oxidizing substance.
Oxygen: A colorless, odorless reactive gas that forms about 21% of the atmosphere.
Palisade Mesophyll: One or more layers of cells located directly under the epidermal cells of the adaxial leaf blade surface.
Palmate Venation: A leaf venation type in which the main veins of the blade radiate from a common point at the base of the leaf.
Palmately Compound: A type of compound leaf in which all leaflets originate from a central common point at the base of the compound leaf.
Palmately Lobed Margins: A type of lobed leaf margins in which the lobes all radiate out from a central common point at the base of the leaf.
Panicle: A loose branching cluster of flowers.
Parallel Veined: Having veins that are arranged nearly parallel to one another and do not branch and come together again.
Parent Material: Disintegrated rock material usually unconsolidated and unchanged or only slightly changed; the underlying geological material from which soil horizons form.
Peat: A brown deposit resembling soil, formed by the decomposition of vegetable matter in the wet acidic conditions of bogs and fens, often used as a soil amendment.
Peduncle: The stalk bearing a flower or fruit, or the main stalk of an inflorescence.
Perfect Flower: A flower that has male and female structures in one flower.
Perfoliate Attachment: A leaf attachment pattern where the stem appears to grow through a leaf.
Petal: Each of the segments of the corolla of a flower, which are modified leaves and are usually colored.
Petiolate Attachment: A leaf attachment pattern in which a leaf is attached to the stem of a plant via a smaller leafstalk, or petiole.
Petiole: A leafstalk, or smaller stem that connects a leaf to a plant's stem.
Phloem: The living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis.
Phosphorus: A poisonous, combustible metal present in soil.
Photosynthesis: The process by which green plants use sunlight to synthesize foods from carbon dioxide and water.
Pinna: A leaflet on a secondary vein in a compound leaf structure.
Pinnately Compound: A leaf which is divided into smaller leaflets, which are arranged on each side of a leaf's central stalk.
Pinnate Venation: A type of venation pattern in which the secondary veins run parallel to each other from the midrib toward the margin.
Pinnately Lobed Margins: A leaf whose lobes are arranged on either side of a central axis, like a feather.
Pinnule: A leaflet on a compound leaf, comprised of pinnas.
Pistil: The female organ of a flower, comprised of a stigma, style, and ovary.
Pith: A continuous central strand of spongy tissue in the stems of most vascular plants.
Polar Nuclei: Two nuclei that migrate toward the center of the embryo sac and fuse with a male nucleus (sperm) to form the primary endosperm nucleus which divides and sometimes forms the endosperm.
Pollen Grain: Microscopic particles, typically single-celled, of which pollen is comprised. They have a tough coat.
Pollen Sac: One of the pouches of a seed plant anther in which pollen is found.
Pollen Tube: The hollow tube that develops from a pollen grain when deposited on the stigma of of a flower. It penetrates the style and conveys the male gametes to the ovule.
Pollination: The transfer of pollen to a stigma, ovule, flower or plant to allow fertilization.
Pollinator: An insect or other agent or animal that conveys pollen to a plant and so allows fertilization.
Pore Space: The porosity of soil; the space between mineral grains in soil, formed from varying parts water and air.
Potassium: A soft, silvery-white reactive alkali metal found in soil.
Raceme: A flower cluster with the separate flowers attached by short equal stalks at equal distances along a central stem; the flowers at the base of which open first.
Receptacle: The part of a flower stalk where the parts of the flower are attached.
Respiration: A process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.
Reticulated: Net-veined.
Rhizome: A continuously growing underground stem that puts out lateral shoots and adventitious roots at intervals.
Rock: A natural substance composed of solid crystals of different minerals that have been fused together into a solid lump.
Roots: The part of a plant which attaches it to the ground or to a support, typically under the soil surface that also convey water and nourishment to the rest of the plant via numerous branches and fibers.
Runner: A slender stem that grows horizontally along the ground, giving rise to roots and vertical stems and branches at nodes.
Saline Soil: Soil that contains enough soluble salts to interfere with the ability of plants to take up water.
Sandy Soil: A soil containing more than 85% sand-sized particles by mass.
Scale Leaves: Small modified leaves that are usually colorless, though they can be green. They are found most commonly on conifers.
Scalloped Margins: A type of leaf margin that has rounded scallops.
Secondary Veins: The second thickest veins on a leaf that arise from the midrib, or central vein.
Seed: A flowering plant's unit of reproduction, capable of developing into another such plant.
Seed Coat: The protective outer coat of a seed.
Seedling: A young plant, especially one raised from seed and not from a cutting.
Self-Pollination: The pollination of a flower by pollen from the same flower or from another flower on the same plant.
Sepals: Each of the parts of a calyx of a flower, enclosing the petals and typically green and leaflike.
Serrated Margins: Leaf margins that are toothed and saw-like.
Sessile Attachment: A leaf attachment pattern that indicates a leaf directly attached to a stem.
Sexual Reproduction: The production of new living organisms by combining genetic information from two individuals of differing sexes.
Sheath Leaf: A leaf whose lower portion encircles the stem.
Sheathing Attachment: A type of leaf attachment with a tubular portion of the leaf blade surrounding the stem below the base.
Shoot Apex: The growing tip of the plant shoot in which all cells are capable of repeated division.
Silt: Fine sand, clay or other material carried by running water and deposited as a sediment, especially in a channel or harbor.
Simple Fruit: One that develops from a single ovary.
Simple Leaf: A leaf whose blade is not divided to the midrib, though it can be lobed.
Single Flower: A flower in which a single row of petals is arranged around the center of the flower head.
Sodium: A soft silver-white alkali reactive metal found in soil.
Soil Composition: The nutrients and various other materials and substances present in a sample of soil.
Soil Profile: A vertical succession of horizons in a local soil.
Soil Reaction (pH): The degree of soil acidity or alkalinity.
Soil Structure: The way individual particles of sand, silt, and clay are assembled in a soil.
Soil Surface: The immediate uppermost loose layer of the earth containing organic matter and soil organisms suitable for plant growth.
Soil Texture: A summation of the proportions of sand, silt, and clay content in a soil sample.
Soil Type: A classification of soil based on its percentages of clay, silt and sand.
Spadix: A spike of minute flowers closely arranged around a fleshy axis and typically enclosed in a spathe.
Spathe: A large, sheathing bract enclosing the flower cluster of certain plants.
Species: A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. It is a taxonomic unit that ranks below genus.
Sperm: The male sex cell of a plant.
Spike: An unbranched, indeterminate inflorescence, bearing sessile flowers.
Spine: A firm, slender, sharp-pointed structure that is a modified leaf.
Spined Margins: A type of leaf margin that has sharp points.
Spongy Mesophyll: A complex, porous tissue found in plant leaves that enables carbon capture and provides mechanical stability.
Stamen: The male fertilizing organ of a flower, typically consisting of a pollen-containing anther and a filament.
Stem: A main structural part of a vascular plant that bears buds, shoots, and leaves.
Stigma: The part of the pistil where pollen germinates.
Stipule: A small, leaflike appendage to a leaf that is typically borne in pairs at the base of a leaf stalk.
Stolon: A creeping horizontal plant stem or runner that takes roots at points along its length to form new plants.
Stoma: (plural: stomata) A minute pore in the epidermis of the leaf or stem of a plant which allows movement of gases in and out of cellular spaces.
Storage Leaves: Thick leaves that can be found either above or below the soil surface, as in those of an onion or a succulent plant.
Style: A structure found within a flower that is a slender stalk connecting the stigma and the ovary.
Subsoil: The layer of earth immediately below the surface soil, consisting predominately of minerals and leached materials such as iron and aluminum compounds.
Sulfur: A yellow combustible material found in soil.
Superphosphate: A fertilizer made from treating phosphate rock with sulfuric or phosphoric acid.
Taproot: A straight tapering root that grows vertically downward, forming the center from which subsidiary rootlets form.
Taxonomy: A branch of science concerned with classification of living organisms.
Tendril: A slender threadlike appendage of a climbing plant that grows in a spiraled manner, stretching and twining around structures and support.
Terminal Inflorescence: A type of inflorescence that rises above the leaves of a plant.
Toothed Margins: A type of leaf margins that has small points along it.
Topsoil: The top layer of soil.
Truncate: A leaf shape that ends abruptly, as if cut off at the base or tip.
Transpiration: The exhalation of water vapor through the stomata of the leaves of a plant.
Tuber: A much-thickened underground part of a stem or rhizome.
Turgor Pressure: The pressure exerted by fluid against a cell wall.
Twig: A slender woody shoot that grows from a branch or stem of a tree or shrub.
Umbel: A flower cluster in which stalks of nearly equal lengths spring from a common center and form a flat or curved surface.
Variegation: Exhibiting different colors, especially as irregular patches or streaks.
Vascular Bundle: A strand of conducting vessels in the stem or leaves of plant, typically with phloem on the outside and xylem on the inside.
Vascular System: A network of conducting tissues interconnecting all organs, transporting minerals, water, nutrients, organic compounds, and various signaling molecules.
Vascular Tissue: Complex conducting tissue formed of more than one cell type found in vascular plants.
Venation: The arrangement of veins in a leaf.
Vegetative Bud: A leaf bud; the bud that contains embryonic leaf.
Vegetative Reproduction: A form of asexual reproduction in plants in which multicellular structures become detached from the parent plant and develop into new individuals that are identical to the parent plant.
Vein: Small channels or capillaries that transport water and minerals to and from the leaf of a plant.
Veinlet: A small or secondary vein on the leaf of a plant.
Water: A colorless, transparent, odorless liquid that is the basis of the fluids of living organisms.
Water-Soluble Fertilizer: A fertilizer that can be dissolved in water.
Whorled Attachment Pattern: Three or more equally spaced leaves at a node.
Xylem: Vascular tissue in plants that that conducts water and dissolved nutrients upward from the root and helps form woody elements of stems.
Xylem Vessel: The type of cell found in xylem that conducts water through plants.
Zinc: A silvery-white metal present in soil.
Zygote: A fertilized ovum.
