In addition to their botanical classification and possession of scientific and common names, most plants can be grouped into an assortment of other categories based on physical appearance rather than genetic relationship. Such groupings are artificial, yet serve many needs of professional plant workers, especially the ornamental horticulturists. An understanding of the terms and descriptions to follow is basic to the many career fields in ornamental horticulture.
Woody plants are those having a corky outer surface of bark covering their older stems. The woody plants usually survive the winter, and the woody stems normally increase in diameter each year.
Herbaceous plants are more succulent plants. They lack bark covering, and their twigs usually do not increase much in diameter. They are often unable to survive the winter in cold climates above ground.
Evergreens are plants that retain their leaves all year. While individual leaves drop and are replaced periodically, the overall appearance of the plant remains green.
Deciduous plants are those that drop their leaves and enter a period of dormancy once a year.
Semievergreens may retain their leaves during the winter months, but the leaves discolor and often winter-burn. In southern climates such plants usually are evergreen.
Trees are woody plants, either evergreen or deciduous, that produce a canopy of leaves atop a single stem.
Shrubs are basically the same as trees except that they seldom get as tall and have multiple stems instead of one.
Vines may be woody or herbaceous. Their stems are unable to support the weight of the plants. If the plants are to grow upright, they must be supported by a trellis, fence, or wall.
Groundcovers can be woody or herbaceous, flowering or nonflowering, trailing or compact. At maturity, their height is 18 inches or less.
Annuals are plants that complete their life cycle from seed to fruit to death within one growing season.
Perennials are plants that live several years and, where necessary, can survive cold winter months in a dormant state. They do not die after flowering.
Biennials live two years. The first year is spent in a vegetative stage of development. After a period of winter temperatures, necessary to initiate flower development, the plant flowers during the second year, then dies.
Hardy plants are those that will survive the winter temperatures of a locale.
Tender plants are those that will not survive temperatures below freezing.
Nursery plants are those produced in nursery fields, greenhouses, and container operations for use in residential, commercial, public, and institutional landscapes.
Greenhouse crops are usually herbaceous and often flowering plants grown in greenhouses for sale to retail flower shops and other outlets.
Bedding plants are used to create flower beds and flower borders. They may be annual or perennial but are nearly always herbaceous. They are often grown and sold as multiples in strips of peat moss pots or in shallow plastic trays. Others are sold as singles in 4-inch pots.
Foliage plants are prized more for their leaves and habit of growth than for their flowers or fruit. In temperate regions they are used primarily as indoor plants. In tropical and semitropical regions they are used outdoors.
Native plants are those that evolved in a given area.
Exotic plants are those brought into an area to which they are not native Very often their survival is dependent on care and tending by humans.
Naturalized plants are those brought into an area as exotics that adapt well enough to escape cultivation and grow as successfully as native plants.
Wildflowers are flowering plants numbering over 20,000 species that are able to grow and propagate on their own. Their origin may be either native or exotic, but all have attained the status of naturalized species.
Endangered species are plants that are at risk of extinction throughout a portion or the entirety of their range.
Threatened species are plants that are likely to become endangered in the near future throughout a portion or the entirety of their range.
Rare species are plants that should be protected because of their distinctive characteristics and limited numbers. They may or may not be threatened or endangered.
Aquatic plants are rooted under water. Those of importance to ornamental horticulture, such as water lilies, send their leaves and flowers to the surface.
Specimen plants are visually distinctive due to some feature such as growth habit, flower, bark, or fruit color. The term is applied most often in the landscape profession.
Accent plants, another landscape term, refers to plants different from others with which they may be grouped. The difference is not as marked as with specimen plants, however. It may be only a difference of height, shape, or texture.
Many more horticultural plant categories exist. They are a part of the technical language of the many specialized branches of ornamental horticulture.