The towering, vibrant spikes of blue, purple, and white flowers commonly known as Delphinium and Larkspur are fixtures in many gardens. Their visual similarity often causes people to use the names interchangeably, leading to frequent confusion. While they share a deep botanical heritage and striking appearance, they are not the same plant. Understanding their differences is necessary for proper gardening and safety, as well as botanical classification.
The Botanical Answer: Clarifying the Relationship
Both Delphinium and the plant commonly called Larkspur belong to the Ranunculaceae family, also known as the buttercup family. This shared ancestry explains their similar growth habits and flower structure, but modern taxonomy separates them into distinct genera. The genus Delphinium contains the tall, robust perennial species often grown in formal gardens. The annual Larkspur, known in the floral trade, is generally classified under the genus Consolida. The practical distinction remains: Delphinium refers to perennials and Consolida to annuals. The common name “Larkspur” has historically been applied to both groups, which is the primary source of confusion for gardeners.
Telling Them Apart: Physical Distinctions
The most fundamental difference between the two plants is their life cycle. Delphinium species are true herbaceous perennials, establishing a root system that survives winter to return for multiple years. Conversely, the annual Larkspur, Consolida, completes its entire life cycle within a single growing season, relying on self-seeding.
Leaf and Flower Structure
Observable differences also appear in the leaves and flowers. Delphinium species have large, deeply lobed leaves that are often palmate, creating a dense base. The leaves of annual Larkspur are much more finely divided, giving them a delicate, feathery appearance. The flower arrangement also differs significantly. Delphinium produces dense, elongated spikes with tightly packed flowers, while Consolida flowers are arranged more loosely on a branched stem.
A Shared Trait: Toxicity
Despite their botanical separation, both Delphinium and Consolida share a hazardous chemical composition. All parts of the plants contain highly toxic compounds known as diterpenoid alkaloids, which cause toxic effects on mammals, including humans and livestock. These compounds act as neuro-muscular blocking agents. Ingesting any part of the plant, especially seeds and new growth, can cause symptoms ranging from severe digestive upset and staggering to muscular twitching. The danger is notable for grazing animals, as larkspur causes substantial cattle losses due to this neurotoxic effect, which can lead to respiratory failure. Due to the risk of paralysis, children and pets must be prevented from consuming any part of these popular garden flowers.