Montana Field Guide

Stems glabrous to hairy, 15–60 cm from tuber-like roots. Leaves few, mostly on lower stem; blades 2–9 cm wide; ultimate lobes to 6 mm wide. Inflorescence 4- to 18-flowered; lower flowers shorter than pedicels. Flowers with spreading, deep blue sepals 10–15 mm long; the lower ones longer; petals white to sometimes bluish; the lower blades cleft 1/4 to 1/2-way to base. Fruits 10–18 mm, hairy (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Delphinium sutherlandii has been segragated from D. nuttallianum based mainly on characters of the lower lip petal, which appear to be continuous in our material. Hitchcock recognized D. nuttallianum var. fulvum which appears to correspond to Warnock's D. sutherlandii, but stated that it intergrades with typical D. nuttallianum. Recognition at the species level does not seem warranted at this time.

Delphinium nuttallianum, Nuttall’s Larkspur, is frequently confused with D. depauperatum, Slim Larkspur. Nuttall’s Larkspur, however, has pyramidal inflorescences, lower flowers shorter than their stalks (Lesica 2012), spreading fruits, and ringed seeds (FNA 1997). This contrasts with the cylindric inflorescences, lower flowers the same length or longer than their stalks (Lesica 2012), upright fruits, and winged seeds of Slim Larkspur (FNA 1997).

Vernally moist, sometimes shallow soil of meadows, grasslands, rock outcrops, open forest; valleys to alpine (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

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).