Delphinium elatum is a perennial herbaceous flowering plant that is commonly known as the larkspur. The plant grows between 1 and 2 meters in height and produces multiple thick stems from a thick, fleshy tuberous rootstock. It bears dark green palmately-lobed leaves and large flowerheads with prominent spurs that curve backward. The 6-21 cm long sepals are placed behind the flowerhead and together with the bracts form a small cup that encloses the base of the nectar-rich spurs.
Spur length is up to about 15 cm in smaller larkspurs, but can reach 30 cm in some taller species; spur width is up to 6 cm in some very large species. The 36-55 dark blue to violet, rarely white petals of the flowerhead encircle around 80 orange or yellow stamens. Flowering begins in late spring and may continue until early fall; all larkspurs are self-sterile.
Each flowering stem produces 1 or 2 terminal flowerheads, each subtended by a pair of lance-shaped bracts, one leaflike and about 10 cm long, the other narrower and shorter. Like many other perennial plants of this family, the stems die away at the end of the growing season and are replaced by small tubers. The petal color varies from white to a very light purple, or rarely dark blue or red.
The flowerheads are produced in open sprays or racemes, with up to 100 flowers. Each individual flower is subtended by a pair of pointed bracts and enclosed at its base by a cup-shaped involucre consisting of six spoon-shaped bractlets. The dark blue, pink or white petals are all similar, except the lowest petal, which is larger and broader than the others.
The seed-producing flowers are followed by attractive seed heads that resemble those of some bluebirds. The fruit is a cluster of 2 to 10 follicles, each containing numerous seeds embedded in a sweet pulp.
"Delphinium elatum" is an ornamental plant with large blue flowers that are commonly used in gardens and for cut-flower arrangements. It has been cultivated since 1578, though it is often hard to establish because of the small size of its tubers.