|
Rose, common name for a medium-size family of flowering plants with many important fruit and ornamental species, and for its representative genus. Worldwide in distribution, the rose family contains about 107 genera and 3100 species.
The rose family is placed in an order with 24 other families. This order is sometimes referred to as the rose order. Other important members of the order include the saxifrage family and the stonecrop family. Another family, the coco-plum family, occurs in the lowland Tropics and contains about 400 species, several of which are used locally for their timber, oilseeds, and fruits. Perhaps the best-known member of the family is the coco plum, found in southern Florida on sandy beaches and swamps; its sweet fruits are made into jelly or preserves.
Plants of the rose order may vary greatly in habit, from trees to shrubs or often perennial herbs. The leaves usually have stipules (leaflike appendages at the base of the leafstalk) and are often compound. The flowers usually have five sepals (outer floral whorl) and five petals (inner floral whorl) and numerous stamens (male floral organs). The female portion of the flower consists of from one to many pistils, which are free from one another or are variously fused. The ovary or ovaries (egg-producing portion of the pistil) are hypogynous or, more often, perigynous (half-inferior), with the sepals, petals, and stamen borne on the rim of a tubular structure surrounding the ovary base.
About 70 genera of the rose family are cultivated for food, ornament, flowers, timber, or other uses. Although worldwide in distribution, the family is most abundant in north temperate regions and contains many of the most important fruit trees grown in temperate areas. These include apple, pear, peach, plum, cherry, apricot, almond, nectarine, prune, loquat, and quince. The rambling, usually thorny raspberry, blackberry, and dewberry, or loganberry, are members of a genus of the rose family that also includes the common bramble. The strawberry is also a member of the family. In addition the family contains many important ornamentals: chokeberry, cinquefoil, hawthorn, shadbush, cotoneaster, firethorn, flowering cherry, flowering quince, and mountain ash.
| III |
|
ROSE GENUS AND HYBRIDS |
The rose has been grown and appreciated for its fragrance and beauty since ancient times and today is the most popular and widely cultivated garden flower in the world. The genus contains some 100 species, most of them native to the North Temperate Zone. Some are cultivated in their natural form or as various similar cultivars, but most of the more than 20,000 cultivars are the result of careful hybridization and selection from a few species. The cultivars are classed either as old roses—that is, plants that have essentially reached the end
of their horticultural development, with no new varieties having been introduced in the past 60 years—or as contemporary roses—that is, plants that are currently being hybridized and selected for new forms. Several hundred new contemporary rose cultivars are introduced each year. In the United States, some 20 million rose plants are commercially cultivated annually for cut flowers, and some 40 million plants are produced for landscape and ornamental use.
The classification of cultivated roses is complicated, because of the great numbers of cultivars involved and the amount of artificial hybridization that has taken place. Generally, the classes of old roses are based on selection from one or a few ancestral species or hybrids. Among the popular classes are the hybrid perpetuals, or remontant roses, which produce large, fragrant double flowers in early summer and fewer flowers in autumn. The class of polyantha roses includes many dwarf forms, with flowers produced in dense clusters. Tea roses and China roses are old-rose classes from which the contemporary hybrid tea roses have been derived through hybridization with hybrid perpetual roses. Hybrid tea roses are less hardy but more recurrent-blooming than the old hybrid perpetuals and contain a much wider variety of color and flower form. Many other contemporary-rose classes are based on the hybrid tea roses—for example, floribunda roses were derived from crosses between hybrid tea roses and hybrid polyantha roses, the latter in turn being based on crosses between the old polyantha roses and hybrid tea roses.
Roses may be grown in any good, well-drained soil. Although different varieties respond better to certain soil and climate than to others, sandy soils are usually not as favorable as clay soils, warm temperatures are always preferred, and the plants grow best when not set among other plants. Cow manure is the preferred fertilizer, but other organic fertilizers, especially composts, are also used. The plants usually require severe pruning, which must be adapted to the intended use of the flowers. Most rose varieties are grown by budding on an understock (lower portion of a plant) propagated from seeds or cuttings. Roses must be sprayed frequently with insect poisons and fungicides.
Scientific classification: Roses make up the family Rosaceae of the order Rosales. The representative genus is Rosa. Hybrid perpetuals, or remontant roses, are derived mainly from the hybrid species Rosa borboniana; polyantha roses from the hybrid species Rosa rehderana; tea roses from Rosa odorata; and China roses from Rosa odorata and Rosa chinensis.
|
