Montana Field Guide

Limestone Larkspur is a perennial 10-30 cm tall arising from deep roots branched at least 1 cm below the stem attachment. Leaves are on the lower 1/3 of the stem, with 2-7 basal leaves at the time of flowering. Leaf blades are 1.5-7 cm long, round in outline, with few-many lobes, and glabrous to puberulent. Sepals are bright, dark blue, 16-21 mm long, and there is a cleft in the lower petals at least 2 mm deep.

Flowering late spring to early summer although usually somewhat later than the typical subspecies where the two overlap.

Distinguished from the widespread Delphinium bicolor ssp. bicolor by the bright blue sepals, the deep cleft in the lower petal blades 2 mm or greater, and upper petals with solid white-lavender tips rather than with distinct purple veins. Previous collections of this taxon have typically been identified as D. andersonii or D. geyeri.

Shortgrass prairie and grass-sagebrush communities on limestone-derived soils, usually with coarse fragments at the surface, or on limestone outcrops. 1300-2100 m elevation.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus appositus, Bombus auricomus, Bombus borealis, Bombus centralis, Bombus fervidus, Bombus flavifrons, Bombus mixtus, Bombus occidentalis, Bombus pensylvanicus, Bombus griseocollis, Bombus impatiens, and Bombus kirbiellus (Plath 1934, Macior 1974, Bauer 1983, Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Koch et al. 2012, Pyke et al. 2012, Miller-Struttmann and Galen 2014, Williams et al. 2014).

STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).