Without seeing the foliage or the plant's growth pattern, you can often identify the type of a rose (Rosa spp.) type, if not its cultivar, by examining and smelling the cut flower. Beginning with about 150 species of the genus, their descendants now number more than 14,000 varieties. Crossbreeding has produced almost infinite combinations of flower characteristics. Therefore, any gardener should be able to select a rose to grow, regardless of his climate or favorite rose attributes.
The shape and size of a rose blossom gives the first impression of the type of rose you are viewing. Since 1867, when the hybrid tea rose was introduced, these aristocratic blooms have become the rose standard. Recognizable by their conical shape and high, pointed centers, hybrid teas also feature a single flower on a long stem. Old roses, those grown before the development of the hybrid tea, tend to grow in clusters and often have a flattish, rosette flower shape. Other rose petals are cupped, either bending upward or downward. The English shrub rose "Molineux" resembles a round ball of petals. Grow it in U.S. Department of Agriculture plant hardiness zones 5b to 10. Flower sizes range roughly from the climber "Mermaid's" 5-inch blooms to 7/8-inch flowers on the miniature "Popcorn." While the former thrives in USDA zones 7 to 10, the latter requires zones 5 to 9.
Although pink flowers dominate the rose world, varieties now come in all colors except blue and black. Only as breeders began to develop hybrid tea roses did yellow, orange and true red flowers become available. Old roses had a limited palette of whites, pinks, purples and dark reds. Today, blendings of two or more colors are commonplace. Petals may be striped or speckled, or their top and underside may boast different colors. Plus, flower colors that change, intensifying or lightening, as the buds mature into open blossoms no longer surprise.
Along with the pollinators they are designed to attract, humans enjoy the variety of fragrances roses release. Common rose scents include apple, honey, clove, musk, anise, banana, orange, violet and raspberry. Considered more fragrant than modern roses, old roses carry signature scents according to their classification. Gallica roses, treasured for potpourris, have intense, spicy aromas, while damask roses sport fruity perfumes. When cultivars with unrelated fragrances are crossed, their offspring generally lack any noticeable scent. Glands on the lower petal surfaces, as well as leaf surfaces in some varieties, release fragrance, especially on warm, humid days.
In the beginning, most roses had single flowers, composed of five petals. Obviously, rose blossoms now usually far exceed five petals. Roses with nine to 16 petals fall into the semi-double class. Seventeen to 25 petals on a rose denotes a double flower. Full is the designation for a flower with 26 to 40 petals, and very full refers to any rose featuring over 40, up to 150, petals. Actually, these roses still only possess five true petals. The remaining petaloids are modified stamens, producers of the flower's male pollen. This means that very full rose blooms probably have few to no functional stamens, making them sterile as male parents. Since such plants seldom perpetuate themselves in nature, rosarians must cultivate them in the laboratory.