2009 Kansas Wildflower of the Year
PRAIRIE LARKSPUR Delphinium virescens
flowering stalk (x 2)
DERIVATION OF NAMES
"Larkspur" - an old English name for the plant from the resemblance of the spur on the flower to the long hind claw of the European crested lark; "Delphinium" - from the name (delphinion) used for these plants by the early Greek botanist Dioscorides because of the resemblance of the unopened flower to a dolphin; "virescens" from Latin) - becoming green.
OTHER COMMON NAMES
Plains larkspur, larksheel.
OTHER SCIENTIFIC NAMES (SYNONYMS)
Delphinium carolinianum subsp. penardii
Buttercup or crowfoot family (Ranunculaceae). This species can be recognized as a crowfoot by the petal-like sepals, the many stamens, the three simple pistils in each flower, and the highly dissected leaves.
The tall wand-like stalks of prairie larkspur wave above the grasses in the late spring and early summer prairie. These plants with spurred whitish flowers make an ornamental addition to any planting. This species grows from 2 to 3 ½ feet tall. The shoot is simple or has a few to many upright branches. The stems of the mature plant are reddish and the leaves are light green, both with a grayish cast because of the dense short white hairs covering them. The leaves are divided and subdivided into palmately arranged narrow segments. Blooming occurs from May to June. Each stem ends in an elongate upright inflorescence (raceme) of 5-30 white flowers with a few dark blue or purplish blotches. The sepals are petal-like and irregular, the upper one having a long backward extended spur. The small petals are in the center of the flower. The two upper petals have nectar-bearing spurs that extend into the spur of the sepal and the two lower petals are bearded with hairs. The flowers are approximately 1 inch long (including the spur) and 1 inch across. The first flowers to open are at the bottom of the inflorescence. Individual flowers are in bloom for a number of days and an inflorescence may have flowers for almost a month. The inflorescence can be used as a cut flower.
GROWTH CHARACTERISTICS AND MANAGEMENT
Prairie larkspur is a perennial. One to a few stout upright stems grow from a cluster of narrow tuberous roots. Leaves are both basal and alternately arranged on the stem. The basal leaves have long stalks (petioles). The leaves on the stem become smaller with shorter stalks up the stem. Upright branches may develop from many of the leaf axils. Prairie larkspur volunteers readily from seed but it does not spread vegetatively. It does not spread aggressively. The plant grows in fall and spring but is dormant during the middle of the summer. Young plants grown from seed usually flower in the second season.
Several species of larkspurs have been used in a preparation with soap to kill lice (Kindscher 1992). Smith and Smith (1980) reported that it was used as a narcotic by American Indians. Wood (1979) listed plants of this species as being beneficial to wildlife.
RELATIONS TO ANIMALS
The entire plant of prairie larkspur is toxic to cattle when fresh but loses this toxicity when dried. Toxicity is greatest in early spring and declines as the plant becomes mature. Horses rarely eat enough of the plant to be poisoned and sheep seem to be resistant to the toxins (Stephens 1980). Eddy (1992) found prairie larkspur equally common on ungrazed roadsides and in grazed pastures in the Flint Hills of Kansas. Costello (1969) reported that pronghorn ate the prairie larkspur. The main pollinator of this plant is the bumblebee. The process of pollination is described by Bare (1979).
SEEDS AND FRUIT
Generally three elongate upright capsules (approximately 3/4 inch long) develop from each flower. After turning yellow the capsules open at their tips and later split along one side. The seeds are thrown out and scattered as the wind shakes the dry brown capsules. The seed is brown, variable in shape and 1/16 – 1/8 inch in length. The seed is covered with rows of thin scale-like ridges. The seeds should be collected as soon as the capsules are dry in June.
seed capsule (x 1 3/4)
seed (x 10)
Seed germination is best at cool temperatures. Baskin and Baskin (1988) studied this species (from Kentucky) and reported that seeds planted in summer mostly germinated in the next fall with some germinating the following fall. They reported that fresh seed was conditionally dormant, able to germinate only at cool temperatures. After ripening at warm temperatures increased the range of temperatures over which they would germinate. They also reported that light exposure did not affect germination. Smith and Smith (1980) reported that these seeds germinated best at cool temperatures and could be planted fresh or after dry stratification. Our studies with moist stratification have not given consistent results but seeds often germinated in the refrigerator.
Seeds can be planted in the field in late summer or early spring. Plants can be started indoors in pots or can be started in flats and transplanted to pots after the first true leaf appears. Seedling survival is often low in the greenhouse. They survive best at low temperatures.
The pair of medium-sized cotyledons are borne on stalks as long or longer than the cotyledons. Each cotyledon is oval, approximately 1 1/2 times as long as wide and pointed at the tip. The true leaves arise basally one at a time on long upright stalks. The first true leaf is broad with three lobes.
seedling (actual), true leaf (actual)
Rock (1972) reported that this species can be grown from root divisions in spring or fall and from cuttings. Smith and Smith (1980) reported that it could be grown from divisions.
Prairie larkspur is found throughout Kansas. It is found in much of the Great Plains from Alberta to Minnesota and south to Texas.
HABITAT. The prairie larkspur grows in prairies and other grasslands in upland open sites. Weaver and Fitzpatrick (1934) found this species in 36% of the upland prairies and 32% of the lowland prairies they studied.
Copyright © 1992 Kansas Wildflower Society
Source: Growing Native Wildflowers by Harder and Platt. page 92.5