The most precise way to understand the difference between carnations and Dianthus is through their botanical classification. Dianthus is the name of a genus, which is a group of closely related species. The genus Dianthus belongs to the family Caryophyllaceae. Carnations are not a separate genus; they are a specific type of Dianthus. Their botanical name is Dianthus caryophyllus. Therefore, all carnations are Dianthus, but not all Dianthus are carnations. This is analogous to the relationship between the genus Canis and the species Canis lupus (wolf) and Canis familiaris (dog). The term "Dianthus" encompasses a wide variety of species and cultivars, including carnations, sweet Williams (Dianthus barbatus), and the common garden pinks (e.g., Dianthus plumarius).
While all Dianthus share certain characteristics, such as opposite, simple leaves and flowers with five petals that often have fringed or serrated edges (the name "Dianthus" comes from the Greek for "divine flower"), there are distinct morphological differences between carnations and other members of the genus.
Flowers: Carnations (Dianthus caryophyllus) are renowned for their large, densely-petaled, and often fragrant flowers. The blooms are typically solitary or borne in small clusters on long, sturdy stems, making them ideal for cut flowers. The petals can be single, semi-double, or double. In contrast, many other Dianthus species, like cottage pinks (Dianthus plumarius), produce smaller, simpler flowers that often appear in greater profusion atop shorter, branching stems. Their fragrance can be spicier, reminiscent of cloves.
Foliage and Growth Habit: Carnations tend to be taller plants, often growing up to 30-80 cm (12-31 inches) tall. They have long, narrow, bluish-green or gray-green leaves that form a clump. Many other Dianthus species are lower-growing, mat-forming plants, commonly referred to as pinks. These are popular in rock gardens or as border edging, with foliage that is often finer and more grass-like.
The differences in their physical form lead to distinct uses in horticulture. Carnations are primarily cultivated for the commercial floriculture industry. Their long, strong stems and large, long-lasting blooms make them one of the most popular cut flowers globally. They are often grown in controlled greenhouse environments to produce the uniform, high-quality blooms demanded by the market.
Other Dianthus species are predominantly grown as ornamental garden plants. Their value lies in their prolific flowering, compact growth habit, and hardiness. They are staples in perennial borders, rockeries, and containers, prized for adding color and texture over a long season. Many modern garden varieties are hybrids developed for specific traits like disease resistance, bloom size, and a extended flowering period, but they generally retain the smaller, more numerous flower structure of their wild ancestors rather than the single, massive bloom of the standard carnation.
The distinction is also rooted in history and common naming conventions. The name "carnation" has been used for centuries specifically for Dianthus caryophyllus. It is thought to derive from the Latin "corona" or "coronation," as the flowers were used in ceremonial garlands, or possibly from "carnis" (flesh), referring to the original pinkish-color of the flowers. The term "pink," used for many other Dianthus species, originally referred to the frilled or pinked edges of the petals, not necessarily the color. Over time, "Dianthus" has become the catch-all scientific and gardening term for the entire genus, while "carnation" remains the specific common name for the large-flowered types, particularly those used by florists.
