The term "perennials" commonly means "hardy herbaceous ornamental plants." Hardy perennials are, with some exceptions, nonwoody plants having roots that live through the winter while the tops die back to the ground, particularly in northern climates.
This distinction separates hardy perennials from tender perennials and annuals, which flower, set seed and die in the autumn frosts; and also from biennials, which take two years to complete the life cycle. In the first year biennials form low rosettes of leaves; the next year, they send up flowering stems and die. Many biennials seem to be perennial simply because they reseed themselves easily.
Some perennials will last almost indefinitely. Others tend to be short-lived and many last only a few years. Peony, daylily and iris are extremely long-lived, while columbine, shasta daisy and lupine tend to be short-lived, flowering for two or three years. When selecting plants, remember that "perennial" doesn't necessarily mean "perpetual."
The maintenance required for perennials also varies with the species. For example, chrysanthemum and delphinium need attention each year, whereas hosta, peony and balloon flower generally require little care after they are established. A relatively low-maintenance garden is possible, but it requires careful selection of plants well suited to the climate and planted in an appropriate location.
The following perennials will be excluded from this bulletin. Trees and shrubs, although they are perennials, have woody plant parts that normally do not die back to the ground each winter. Bulbs, tubers and corms have specialized methods of food storage and are usually treated separately, as are ferns and the less common wild-flowers.
Perennials are usually sold under their botanical names (genus, species, cultivar) by the more reputable nurseries. This is because common names can be confusing: one plant may have three different common names, or one common name may refer to three different plants. However, every plant has only one unique botanical name. Occasionally, these names are changed by plant scientists to better describe the plant. When that happens, the old name becomes a synonym for the new.
Common name: Garden mum
Synonym: Chrysanthemum X morifolium
Cultivars: 'MinnGopher' 'Snowsota' 'Mellow Moon'
Most modern reference books on perennials refer to the plants by botanical name, so learning to use these specific names can help you find information more quickly and accurately.
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