Lupinus polyphyllus var. polyphyllus

Native to the Alaska, Colorado, Idaho, Montana, Nevada, Oregon, Washington, and Wyoming. Introduced in the midwest; escaped cultivation.

Moist. Forest edges, fields, shores, roadsides. Full sun to light shade.

June to July

Violet or blue

36″ to 40″

This is an erect, perennial forb that rises from a deep taproot. It can get from 20″ to 60″ tall, though in Minnesota it is usually 36″ to 40″ tall at maturity.

In the first year it develops a rosette of basal leaves. In the second year it sends up flowering stems. The stems are erect, unbranched, stout, round, and thinly hairy.

Stem leaves are alternate and are palmately divided into 11 to 17 leaflets. Lower leaves are on leaf stalks that are up to 17¾″ long, upper leaves are on shorter stalks.

The leaflets of the lower leaves are inversely lance-shaped, up to 6″ long and ⅝″ wide. The longest leaflets are about ½ as long as the leaf stalk. The upper surface is hairless or almost hairless. The lower surface is hairy. The margins are untoothed.

The inflorescence is a dense, cone-shaped, 8″ to 16″ tall spike with up to 80 flowers.

The individual flowers are ⅜″ to ⅝″ long. The 5 petals are shades of violet or blue and form a butterfly-like corolla, typical of plants in the Pea family. They are organized into a banner petal at the top, two lateral wing petals, and between the wings two petals fused into a keel. The banner is curved upward. There are 10 stamens; 5 with short filaments and long anthers, and 5 with long filaments and short anthers.

The fruit is a densely hairy, ¾″ to 2¼″ long pod containing 3 to 9 seeds. When ripe the pods open explosively, spreading the seeds a short distance.

Sundial lupine (Lupinus perennis var. perennis) is a smaller plant, no more than 24″ at maturity. Its leaves are divided into 7 to 11 leaflets.