Delphinium treleasei

Species Native to Missouri
Common Name: Trelease's larkspur 
Type: Herbaceous perennial
Family: Ranunculaceae
Native Range: Missouri, Arkansas
Zone: 5 to 7
Height: 2.00 to 4.00 feet
Spread: 1.00 to 2.50 feet
Bloom Time: May to June
Bloom Description: Blue to bluish-purple
Sun: Full sun
Water: Medium
Maintenance: Low
Flower: Showy
Attracts: Butterflies
Tolerate: Deer

Culture

Best grown in medium moisture, well-drained, rocky limestone soils in full sun. Appreciates some afternoon shade in hot summer climates. Needs protection from strong winds. Remove spent flower spikes to encourage additional bloom and/or a possible second, albeit sparse, autumn bloom. Dislikes the hot and humid climates of the deep South, but generally has better tolerance for these conditions than most of the delphinium hybrids. May be grown from seed.

Noteworthy Characteristics

Delphinium treleasei, commonly called Trelease's larkspur, is a rare species that is native to only six counties in the southeastern Ozark region of Missouri where it is most often found on limestone glades. It grows 2-3' (less frequently to 4') tall, and features loose terminal racemes of deep blue to bluish-purple flowers which bloom in spring. Individual flowers (to 1" long) are complex and asymmetrical and feature five sepals, one of which is spurred into a distinctive prong resulting in the common name. Lower petals have yellow beards. Deep green leaves are narrowly and deeply divided. As is the case with many of the buttercup family members, all parts of this plant are poisonous.

Genus name comes from the Greek word delphis meaning dolphin in reference to the flower bud shape of some species purportedly resembling a dolphin.

Specific epithet honors William Trelease, director of the Missouri Botanical Garden from 1889 until 1912.

Problems

Larkspurs are generally susceptible to powdery mildew, botrytis blight, leaf spots and crown rot. Slugs and snails are sometimes visitors. Taller plants sometimes need support. Larkspurs generally grow best in cool summer climates, however this native species should do well in the St. Louis area.

Garden Uses

Rock gardens. Borders. Cottage gardens. Native plant areas. Best massed or in small groupings.