The Dogwood, belonging to the genus Cornus, is a diverse group of plants known for their ornamental value across all four seasons. Current scientific classification recognizes approximately 30 to 60 species worldwide. These species include not only the familiar flowering trees but also a variety of shrubs and low-growing groundcovers. The wide global distribution of the genus, which includes temperate regions across North America, Eurasia, and South America, contributes to this significant diversity.
Global Diversity and Scientific Classification
The variation in the species count stems from different taxonomic treatments of the Cornus genus. Some systems group similar plants into fewer, broader species, while others divide the genus into numerous smaller subgenera. The genus is separated into three primary life forms. The first group consists of true trees, which develop a single trunk and a defined canopy structure.
A second, much larger group is composed of multi-stemmed shrubs that typically grow in dense clusters and rarely exceed 15 feet in height. The third group includes a few herbaceous perennial species, such as the Canadian and Eurasian dwarf cornels (Cornus canadensis and Cornus suecica). These are low-growing, non-woody groundcovers. This highlights that “dogwood” refers to a family of plants with varied growth habits, not just large flowering trees.
The Most Common Ornamental Tree Varieties
The most recognizable types of dogwoods are the ornamental trees, prized for their showy spring displays. The North American Flowering Dogwood (Cornus florida) is popular and native to the eastern half of the continent. This species typically blooms in early to mid-spring, often before the leaves fully emerge. It features four large, rounded bracts surrounding a small cluster of true flowers. Its fruit is a small, bright red drupe that provides food for migrating birds in the fall.
The Asian Kousa Dogwood (Cornus kousa) is a close relative native to East Asia, including China, Japan, and Korea. This species blooms later than its American counterpart, usually three to four weeks after C. florida. The Kousa Dogwood is more resistant to fungal diseases, and its bracts are noticeably more pointed. Instead of a small drupe, it produces a unique, globose, compound fruit that resembles a raspberry or strawberry. It also develops attractive exfoliating bark as it matures.
Shrub and Bush Varieties Used for Stem Color
Dogwood types that grow as shrubs are primarily cultivated for their structural form and vibrant winter stem color. These species are multi-stemmed and tend to spread outward, forming dense thickets, distinguishing them from the single-trunked ornamental trees. The Red Osier Dogwood (Cornus sericea) is a prime example, known for its brilliant, multi-hued stems. Cultivars of this North American native and its Eurasian relative, the Tatarian Dogwood (Cornus alba), display stems in shades ranging from crimson and scarlet to golden yellow and coral.
These varieties produce their most intense color on younger wood, which is why they are often pruned heavily in late winter or early spring. This practice encourages the growth of new shoots, ensuring the brightest display when the leaves drop. The flowers on these shrubs are less prominent, appearing as flat clusters of small, creamy-white blossoms, followed by bluish-white berries. Their tolerance for moist to wet soil makes them valuable for stabilizing streambanks and utilizing damp areas.