Horticulture Vocabulary

Air drainage

The flow of cold air down a hill. Plant crops that are sensitive to late spring and early fall frost on slopes, preferably south-facing, so that cold air will drain downhill and settle in the low spots below the planted area

Air layering

A propagation method. A cut is made three-quartets of the way through the stem at an angle of 45 degrees. A toothpick is inserted to keep the cut from sealing itself closed. The cut is wrapped in sphagnum moss that has been soaked in water and wrung out. This is then wrapped in plastic and tied at the top and bottom with ties.

Alternate leaf arrangement

Leaves are arranged at one leaf per node on different sides along the stem.

Annuals

Plants that complete their life cycles in one year or less.

Anther

The part of the flower (on the upper part of the stamen) in which pollen is produced.

Anthracnose

A type of leaf or fruit spot disease caused by a fungus.

Arms

In a grape plant, all main branches two years and older.

Asexual reproduction

Duplicating a plant from any cell, tissue or organ of that plant.

Axillary buds

Buds that are borne laterally on the stem in the axils of the leaves.

Bare Root

Biennials

Plants that require 2 years, or 2 growing seasons with a dormant period in between, to complete their life cycles.

Biological control

Reducing pests by utilizing other organisms. For example, controlling gypsy moths by using Bacillus thuringensis, a disease that affects the gypsy moth and is readily available in garden centers.

Blade

The flattened, green portion of the leaf.

Bolting

Going to seed. Plants will produce a flower stalk and seeds, and then die before the end of the season. Lettuce and other crops will bolt during very hot temperatures. Unless you are growing your crop for the seeds, you want to delay bolting.

Botrytis blight

A gray, felt-type mold that covers parts of a plant and causes stunting, dieback, and distorted growth.

Branch

The part of the tree that arises from the trunk and supports shoots, twigs and leaves. Budding. A type of grafting in which a non-fruitful (vegetative) scion is placed in a stock plant.

Buds

An undeveloped stem, consisting of a tiny bundle of cells, from which leaves, lateral buds, flower parts or all three will arise.

Bulb

A budlike structure that consists of a small stem with closely crowded fleshy or papery leaves or leaf bases.

Bulbil

An aerial bulblet.

Bulblet

Miniature bulbs that develop from meristems in the axils of scaly bulbs.

Burpless

Canes

Previous season's growth from the arms or trunk of a grape plant; or, the supporting part of the raspberry plant, similar in function to the trunk of a tree.

Capsule

Simple, dry, dehiscent (see definition of dehiscent) fruit with two or more locules (the cavities of the ovary of the pistil of a flower) which split in various ways.

Catkin

A type of spike arrangement of flowers on the floral axis that has unisexual flowers made up of sepals and petals.

Certified seed

The progeny of registered seed stock. It is the final stage in the expansion program and is certified with a metal seal and blue tag.

Chilling injury

Damage to certain horticultural products, such as banana, papaya, cucumber and sweet potato, which results from exposure to cold but above-freezing temperatures.

Chilling requirement

A cold period required by certain plants and plant parts to break physiological dormancy or rest. The chilling requirement is expressed in terms of the required number of hours at 7 degrees centigrade or less.

Cold Climate

Cold Frame

Cold storage

A type of insulated storage utilizing mechanical refrigeration to maintain a stable, cold temperature for long-term storage.

Commercial floriculture

Area of horticulture that includes the commercial production and distribution of cut flowers, flowering pot plants, foliage plants and bedding plants.

Companion Planting

Complete fertilizer

A fertilizer that contains nitrogen, phosphorus, and potassium.

Complete flower

Flower composed of a short axis or receptacle from which arise four sets of floral parts-sepals, petals, stamens, and pistils.

Compost

Compound leaf

A leaf with the blade divided into several leaflets or sections.

Compound umbel

A type of flower structure in which a series of simple umbels (see definition of umbel) arise from the same point on the main axis.

Corms

Short, fleshy, underground stems with few nodes and very short spaces between nodes. Gladiolus and crocus are cormous plants.

Corymb

Type of raceme flower cluster in which the pedicels of the lower flowers are longer than the pedicels of the upper flowers, resulting in a flattopped flower cluster.

Cover Crop

Cross-pollination

The process in which pollen is transferred from an anther (the upper part of the stamen in which pollen is produced) of one flower to the stigma (the pollen-receiving site of the pistil) of a second flower of a different cultivar.

Cultivar

A plant derived from a cultivated variety that has originated and persisted under cultivation, not necessarily referable to a botanical species, and of botanical or horticultural importance, requiring a name.

Cuticle

The waxy covering on leaves or fruit, which protects the tissue against excess moisture loss.

Cuttings

Detached vegetative plant parts which when placed under conditions favorable for regeneration will develop into a complete plant with characteristics identical to the parent plant

Cyme

A broad, more-or-less flat-topped determinate (having a fixed number) flower structure in which the central flowers bloom first.

Day-neutral plant

A plant that will flower under any daylength.

Deadhead

Deciduous

Trees or plants that shed their leaves every year.

Dehiscent

Type of dry fruit in which the carpel (a simple pistil) splits along definite seams at maturity. Determinate growth. Limited growth.

Determinate

Dioecious

Species that produce male and female flowers on separate plants.

Direct Sow

Disbudding

The removal of vegetative or flower buds.

Diseased plant

A plant that is abnormal because of a disease-causing organism or virus.

Disease resistant

Disease Tolerant

Dormancy

A state of suspended growth or the lack of outwardly visible activity caused by environmental or internal factors.

Drip irrigation

The application of small quantities of water directly to the root zone through various types of delivery systems on a daily basis.

Drought Tolerant

Drupe

Type of fruit with a thin outer skinlike region, a center portion that is thick and fleshy, and an inner area that is hard and stony.

Endocarp

The inner area of the fruit wall. Entomology. The study of insects.

Epidermis

The outer layer of cells of all parts of a young plant and of some parts of older plants, such as leaves and fruits. These cells are usually covered with a waxy substance, called the cuticle, that minimizes water loss.

Etiolation

Lanky, weak, pale plant growth resulting from low or no light plant growth conditions

Exocarp

The outer skin like region of the fruit wall.

Fallow

A system in which land is left without a crop for an extended period to accumulate moisture and restore nutrients.

Fleshy fruits

Classification of fruits that includes the berry, drupe, and pome. They have a fruit wall that is soft and fleshy at maturity.

Floriculture

The study of growing, marketing, and arranging flowers and foliage plants.

Flower

A shoot of determinate (limited in number) growth with modified leaves that is supported by a short stem; the structure involved in the reproductive processes of plants that bear enclosed seeds in their fruits.

Forcing

The manipulation of environmental factors which makes it possible to produce a marketable pot plant or cut flower out of season.

Foundation seed

Seed stock handled to most nearly maintain specific genetic identity and purity under supervised or approved production methods certified by the agency.

Frost pocket

A depression in the ground into which cold air drains but from which it cannot escape, thus causing it to be an area very subject to freeze injury.

Fruit

An expanded and ripened ovary with attached and subtending reproductive structures. Genes. Basic units of hereditary material that dictate the characteristics of individuals.

Full Sun

Germination

The initiation of active growth by the embryo, resulting in the rupture of seed coverings and the emergence of a new seedling plant capable of independent existence.

GMO

Grafting

The joining of two separate structures, such as a root and stem or two stems, so that by tissue regeneration they form a union and grow as one plant

Growing season

The period from the last spring freeze until the first freeze in the fall. In the United States this ranges from about 100 to 365 days.

Hardening

The result of many changes that occur in a plant as it develops resistance to adverse conditions, especially cold.

"Hardening off

" The treatment of tender plants to enable them to survive a more adverse environment. Treatments involve withholding nutrients, lowering temperatures, allowing temporary wilting, and other methods to slow growth rate.

Hardiness

Hardpan

A layer in the soil that cannot be penetrated and which restricts root penetration as well as movement of air and water.

Hardwood cuttings

Cuttings made from woody deciduous species and narrow-leaved evergreen species, such as grape and hemlocks.

Heading back

Type of pruning cut where the end portion of the shoot is removed but the portion at the base is not.

Heirloom

Herbaceous cuttings

Cuttings made from herbaceous plants (see definition below), such as chrysanthemums, coleus, and geraniums.

Herbaceous perennials

Plants with soft, succulent stems whose tops are killed back by frost in many temperate and colder climates, but whose roots and crowns remain alive and send out top growth when favorable growing conditions return.

Herbarium

A collection of plant specimens that have been taxonomically classified, pressed, dried, and mounted on a sheet of herbarium paper.

Herbicide

A material that will kill plants. Herbicides may kill essentially all plants or be quite selective in their activity.

High-pressure sprayer

A sprayer using a high-pressure pump to force the spray through nozzles for both creating a fine spray and delivery to the plant.

Horticulture

The intensive cultivation of plants.

Humus

A dark-colored organic material that is the product of organic matter breakdown by both microorganisms and chemical reactions.

Hybrid

In its simplest form, a first-generation cross between two genetically diverse parents. Imperfect flower. Flower lacking either the stamen or the pistil.

Incomplete flower

Flower lacking one or more of the fours sets of floral parts.

Indehiscent

Type of dry fruit in which the fruit wall does not split at any certain point or seam at maturity. Indeterminate growth. Growth that is potentially limitless.

Indeterminate

Inflorescence

The arrangement of the flowers on the floral axis-a flower cluster.

Interstock

Intermediate stem piece that is grafted between the upper and lower pars of the graft.

Landscape design

The profession concerned with the planning and planting of outdoor space to secure the most desirable relationship between land forms, architecture, and plans to best meet human needs for function and beauty.

layering

A vegetative method of propagation that produces new individuals by producing adventitious roots (roots growing from unusual places) before the new plant is separated from the parent plant.

Leaching

The downward movement of nutrients or salts through the soil profile in soil water. Leaching accounts for nutrient losses but can also be beneficial in ridding a soil of excess salts.