A Green Thumb Glossary

As you read magazines and books and become more knowledgeable about the plants in your landscape, you will come across terms with which you may be unfamiliar.  This glossary will help you understand at least some of them.  Other good sources are regional gardening guides and books such s Gardener's Latin:  A lexicon, by Bill Neal; Taylor's Dictionary for Gardeners:  The definitive guide to the language of horticulture, by Frances Tenenbaum; and Garden Terms, by Michale Pilcher, Lisa Davis and David Hurrion.

• Annual:  A plant whose life cycle is completed in one season.  Examples:  pansies, morning glories, periwinkles, impatients.

• Barerooted:  As opposed to container-grown or balled-and-burlapped plants, these are dug and sold with n soil around roots, and are often less expensive.  Flowering shrubs, roses, fruit and pecan trees and grapes are often sold this way during their dormant season.  Shade trees should generally not be purchased barerooted.

• Botanical name:  The scientific name of a plant; usually appears in italics.  The botanical name consists of two parts:  the first is the genus to which the plant belongs; the second is the species name.  Variety or cultivator names, if any, will follow and will not be italicized and will be set within single quotation marks.  Botanical names have their origin in Latin

• Bract:  A leaf that is modified and appears at the base of a flower cluster or substitutes as a flower.  Poinsettias, dogwoods, hydrangeas and bougainvilleas are examples of plants with showy bracts. 

• Cole crops:  Plants that belong to the genus Brassica, from the cabbage family, including broccoli, cabbage, cauliflower, Brussels sprouts and kale.

• Compost:  Leftover organic matter, such as vegetables, grass clippings and leaves, that is usually mixed with topsoil and manure and allowed to decay.  Once the compost has decayed, it can be used in the garden to improve the texture and fertility of the soil.

• Corm:  The bulblike underground part of a stem, as found on crocus or gladiolus. 

• Cross-pollination:  Transfer of pollen from one flower to the stigma of another, creating offsprings that most commonly have a genetic makeup unlike either of the parent plants.

• Cultivar:  A variety created through horticultural processes that do not occur naturally.  The cultivar name follows the botanical name.  It is not italicized and is set within single quotation marks.

• Deadheading:  The intentional removal of dead flowers or seeds from a plant to encourage or prolong its bloom period.

• Determinate:  These plants reach a fixed height, then develop flower buds at the tip of each stem.  Determinate tomatoes, for example, grow in bush form with all the fruit developing and ripening about the same time.  The harvest period is very short.  In contrast, indeterminate varieties (typically vining types) continue to grow throughout the season, making much larger plants with a longer harvest season.

• Foliar feeding:  Fertilization of a plant through its leaves by use of a water-soluble fertilizer sprayed directly onto them. 

• Forcing:  Causing early growth or blooming of a plant by subjecting it to certain conditions (for example, starting bulbs such as paperwhites, hyacinths or amaryllis, indoors in containers).

• Genus:  Classification of a group of related species.

• Hybrid:  New plant produced from crossing genetically different parents. 

• Inflorescence:  The development and arrangement of flowers on a stem; a flower cluster.

• Loam:  Loose, rich soil of mixed clay, sand and silt.

• Perennial:  A plant that lives for several years and does not die after one season or life cycle.

• pH:  A measure of the acidity or alkalinity of soil from 1 to 14.  7.0 is considered neutral.  Values lower indicate acidic ("sweet") soils, while higher values indicate alkaline ("sour") soils.

• Pinching:  Removing the tip of a stem by squeezing between the thumb and forefinger; encourages the plant to develop new shoots or buds for a fuller look.

• Propagation:  Reproducing plants by planting seed, taking cuttings, layering, grafting or dividing them.

• Pyrethrum:  A natural insecticide made from several insecticides called pyrethrins.  Pyrethrum powder is produced from the flower heads of two species of chrysanthemum grown in the highlands of Africa, South America, and southeast Asia; low toxicity to people and pets.

• Rhizome:  An underground stem-like tissue.  Examples:  irises, Johnson grass, cannas.

• Rootbound:  Where a plant's roots have grown to the capacity of a container and begin to wind around the inside of the container, causing the plant's growth to be stunted until the plant is repotted into a larger container.

• Sepal:  One of the outer, protective "petals" of a flower.

• Sidedressing:  Fertilizer applied to the soil surface around a plant.

• Species:  A classification ranking just below the genus and made up of closely related plants that possibly can cross with one another.

• Taproot:  A thick central root that grows deeply into the soil.

• Tuber:   Short, fleshy underground stem that produces tiny to large leaves and buds (as in potatoes, caladiums, dahlias and tuberous begonias).

• Xeriscape:  A drought-tolerant, low water-usage landscape style developed by the Denver Water Department.