Alpine larkspur

Delphinium ramosum Rydberg var. alpestre (Rydberg) W. A. Weber

Stems 5-25 cm; base green, puberulent. Leaves cauline, 5-20, on proximal 1/5 of stem at anthesis; petiole 1-10 cm. Leaf blade round to pentagonal, 1.5-5 × 2-5 cm, puberulent; ultimate lobes 3-15, width 2-11 mm. Inflorescences 2-8-flowered; pedicel 1-4 cm, puberulent; bracteoles 1-3 mm from flowers, green, linear-lanceolate, 6-10 mm, puberulent. Flowers: sepals dark blue, apex rounded, puberulent, lateral sepals spreading to forward pointing, 11-14 × 5-7 mm, spurs straight except usually slightly down-curved at apex, varying from 20° above to 20° below horizontal, 8-12 mm; lower petal blades ± covering stamens, 4-6 mm, clefts 2-4 mm; hairs sparse, mostly near base of cleft, centered on inner lobes, white. Fruits 7-12 mm, 3.5-4 times longer than wide, puberulent. Seeds unwinged; seed coat cells elongate, surface roughened.

Flowering mid-late summer. Exposed talus slopes on high peaks; of conservation concern; (3400-)3800 m and above; Colo., N.Mex.

Delphinium alpestre is very similar to D . ramosum , possibly divergent from that taxon only since the most recent glaciation of North America, during which ancestors of D . alpestre might have survived on peaks above the ice, while ancestors of D . ramosum survived in valleys below the ice. Since glaciation, D . ramosum apparently has migrated upslope, near but not adjoining populations of D . alpestre .