The Delphinium genus, commonly known as Larkspur, comprises a large group of flowering plants celebrated for their dramatic vertical presence in a garden setting. Most species are herbaceous perennials, meaning the top growth dies back in winter and regrows from the roots each spring, though some are cultivated as annuals or biennials. The approximately 300 species within this genus are native to the Northern Hemisphere and high mountains in Africa. Their sheer height and dense floral display make Delphiniums a popular addition for gardeners seeking to add structure and color.
The Signature Flower Spikes and Color
The appearance of the Delphinium is dominated by its flowers, which are densely clustered along a central, upright stalk called a raceme or spike. An individual flower, or floret, is bilaterally symmetrical and composed of five petal-like sepals. The uppermost sepal extends backward into a long, hollow projection known as the spur, which inspired the common name Larkspur. Inside the sepals are the true petals, typically four in number, which are often small and inconspicuous. These petals frequently form a contrasting central area, called the “bee” or “eye,” which can be white, brown, or black, providing a distinct focal point. The flowers appear in a broad color spectrum that includes true blue, purple, pink, and white. This dense, vertical arrangement of numerous, individually detailed florets gives the Delphinium its characteristic column-like appearance.
Stems and Overall Plant Height
The towering, vertical growth habit of the Delphinium provides significant height to garden borders. The main flowering stem is erect and varies dramatically in size; some alpine species reach only about four inches, while larger meadowland species can exceed six feet in height. Cultivated varieties of Delphinium elatum frequently grow between five and eight feet tall. The stems supporting these flower spikes are often hollow, a structural feature that makes them susceptible to breakage from strong winds or the weight of rain-soaked blooms. Taller varieties require support, known as staking, which is generally done early in the season. The flowering spike forms along the upper section of the main stem, with the flowers opening sequentially from the bottom up.
Defining Features of the Foliage
The leaves of the Delphinium contribute a bold texture to the plant’s overall appearance, contrasting with the delicate look of the flowers. The foliage is typically medium to dark green and features a deeply lobed, palmate structure. This means they are shaped somewhat like a hand, often having five to seven distinct segments that are further divided into pointed or toothed sections. The leaves are clustered and largest at the base of the plant. They become progressively smaller and sparser as they ascend the main stem toward the flower spike. The texture of the leaves can be slightly rough or downy.
Common Delphinium Varieties
Visual differences among Delphiniums result from extensive hybridization, leading to distinct groups based on size and structure. The Pacific Giants group, derived from Delphinium elatum hybrids, represents the largest form, known for stalks that frequently reach up to seven feet tall. These varieties produce thick, densely packed flower spikes. In contrast, the Belladonna group displays a more branching, airy appearance, with looser clusters of flowers on stems averaging three to four feet in height. Dwarf varieties, such as those from the Delphinium grandiflorum species, are highly compact, typically growing only one to two feet tall.