Cherry trees, whether they are the types that yield sweet or sour fruits or are grown merely for their ornamental flowers, all belong to the rose family, Rosaceae. They share many flower characteristics with other fruit trees' flowers--such peach, plum, apricot and apple. Cherry blossoms are usually white or pink, and if pollinated develop into small pitted fruits on thin stems. This distinguishes cherries from other fruits in the rose family.
Although the differences are subtle to the untrained eye, horticulturists describe the shape of cherry tree blossoms based on when the blooms are fully open. Cherry blossoms have five petals and create a cup, bell, bowl or saucer shape. Manmmade selections may produce multiple petaled flowers, but they still are assigned a general flower shape. For example, the chokecherry (Prunus virginiana) yields cup-shaped flowers. Taiwan cherry (Prunus campanulata) is one of the few that displays bell-like blossoms. Higan cherry (Prunus x subhirtella), Yoshino cherry (Prunus x yedoensis) and Sargent cherry (Prunus sargentii) makes bowl-shaped flowers, while Fuji cherry (Prunus incisa) produces saucer-shaped blooms.
Wild species of cherries produce simple, five-petaled flowers. Genetic mutations occur and since they result in multiple rows of petals, they attract the attention of gardeners. These mutations are selected and developed into individual ornamental trees. These mutants' flowers are classified as being semi-double or double in form. Double flowers, like those of the hybrid Kwanzan cherry (Prunus Kanzan) usually have so many more petals in each blossom that each looks like a ruffled pompom. Those with extra petals that aren't as full are given the intermediate, catch-all "semi-double" label, like those of the Fukubana Higan cherry (Prunus x subhirtella Fukubana).
Cherry blossoms range from white to pink in general, with less common colors that range from deep rose to pink-magenta or "red." Some cherry trees flowers open pure white and then with age blush to light pink, or vice-versa. Newer varieties of ornamental cherries are selected because of more ornate or uncommon colors when compared to the parent trees.
In general, cherry trees display their flower in spring when temperatures warm and nighttime frosts no longer occur. Precise timing varies by species, but single flower-formed blossoms tend to open earlier than trees that produce double flower-formed blooms. Moreover, a few ornamental cherry trees rebloom again in autumn, although the floral display typically isn't as grand as the one in spring.
Wild cherry tree species' flowers often carry a light, sweet fragrance. Mutant varieties or excessively bred selections frequently lack fragrance because of the changed flower forms with extra petals or new colors. The showier floral mutations may result in omission of fragrant oils in larger nectaries at petal bases.