Delphinium ajacis L. - Rocket Larkspur

Delphinium ajacis plant

Family - Ranunculaceae

Stems - To +1m tall, erect to somewhat reclining with age,  glabrous to puberulent or glandular(especially above), herbaceous, branching above, from taproot.

Leaves - Alternate, petiolate below to sessile above, with 3-5 deeply divided lobes, typically pubescent. Ultimate divisions linear to linear-oblong, entire (ciliate-margined), to 2.5mm broad. Petioles to 9cm below.

Delphinium ajacis leaves

Inflorescence - Dense terminal racemes to +10cm in flower. Each flower subtended by a pubescent linear bract to 9mm long. Pedicels to 7mm long, thick, expanded at apex, with pair of subopposite linear bracts to 3mm long, dense puberulent.

Flowers - Sepals deep blue-purple,(sometimes whitish to pinkish or mottled in cultivation), the most showy portion of the flower, spurred. Spur to -2cm long, dense pubescent. Petals 4, united, covering other floral organs(stamens and carpel), spurred. Stamens many, included. Filaments white, sparse pubescent, 5-6mm long, expanded at base. Anthers yellow, 1.1mm long. Ovary dense pubescent, 3-4mm long, conic.

Delphinium ajacis flowers

Delphinium ajacis spurClose-up of spur.

Fruit - A follicle to 2cm long, one per flower, variously pubescent. (All other native members of the genus have 3 follicles per flower).

Flowering - July - August.

Habitat - Cultivated.

Origin - Native to Europe.

Other info. - This is an occasional garden annual which is probably not much escaped in the state. The flowers come in a variety of other colors, some of which are shown below:

Delphinium ajacis flower

Delphinium ajacis flower

Photographs taken off Mill Rd., Platte County, MO., 7-1-00.


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