The genus Aquilegia, commonly known as columbine, belongs to the Ranunculaceae (buttercup) family. These herbaceous perennials are characterized by their distinctive floral morphology, which is a key factor in their classification and appeal. A defining botanical feature is the presence of spurs—long, hollow, nectar-secreting tubes that extend backwards from the base of each petal. The shape, length, and orientation of these spurs, along with flower color, sepal arrangement, and plant height, are the primary characteristics used to distinguish between the numerous species, hybrids, and cultivars. Columbines are generally short-lived perennials but readily self-seed, ensuring their persistence in the garden. They are valued for their ability to thrive in partial shade and well-drained soils.
While there are over 60 species of Aquilegia, horticultural focus often falls on a handful of core species that have been extensively hybridized. From a botanical perspective, understanding these species provides insight into the diversity of the genus.
Aquilegia vulgaris (European Columbine): This species is native to Europe and features nodding flowers with short, hooked spurs. The typical flower color is a deep purple-blue, but wild populations can show variation. Its foliage is lacy and grey-green. This species is a primary parent of many traditional garden hybrids.
Aquilegia canadensis (Eastern Red Columbine): A North American native, this species is adapted to rocky woodland areas. Its flowers are pendulous with long, straight, red spurs and contrasting yellow petals and stamens. It is particularly attractive to hummingbirds and is well-suited to wildflower gardens.
Aquilegia caerulea (Rocky Mountain Columbine): The state flower of Colorado, this species is known for its large, upright, and strikingly bicolored flowers. The blooms typically have white petals and lavender-blue sepals with long, straight spurs. It represents a different spur structure and flower orientation compared to its European counterparts.
Aquilegia chrysantha (Golden Columbine): Native to the southwestern United States, this species is valued for its tolerance of warmer climates and its large, fragrant flowers with long, prominent spurs. The flowers are typically yellow, hence the name "chrysantha" meaning "golden flower."
Plant breeding has produced an extensive range of columbine varieties that often blur the lines between pure species. These are grouped based on their growth habits and floral characteristics.
McKana Giants and Songbird Series: These are large-flowered hybrids often derived from A. caerulea and A. chrysantha. They are characterized by very long spurs and upright, outward-facing flowers in a wide array of bicolored and pastel combinations, including pinks, yellows, blues, and whites.
Barlow Series: These are double-flowered hybrids originating from A. vulgaris. The "double" effect is created by the petaloid transformation of the stamens, resulting in a dense, pom-pom-like flower with no visible spurs. They come in shades of blue, pink, purple, and black.
Dwarf Varieties: Cultivars like Aquilegia flabellata ‘Mini-Star’ and others are selected for their compact growth habit, typically under 12 inches tall. They are ideal for rock gardens or the front of borders, retaining the charming flower shape but on a smaller scale.
The columbine flower is a fascinating study in co-evolution. The spur is a specialized adaptation for pollination. The length and curvature of the spur often correspond to the tongue length of its primary pollinator. For example, the long spurs of A. canadensis are perfectly suited for hummingbirds, while the shorter, hooked spurs of A. vulgaris are often pollinated by bees. The nectar stored at the tip of the spur rewards only those pollinators with the appropriate anatomy to reach it, ensuring efficient pollen transfer between conspecific plants. This reproductive strategy has driven the morphological diversity observed within the genus.
