[The Lupines of the Columbia River Gorge]

Small-flowered Lupine

Lupinus bicolor ssp. microphyllus

Lupinus micranthus

Small-flowered lupine as seen from Catherine Creek, central Columbia River Gorge..............May 14, 2006.

Characteristics:

Small-flowered lupine is a small annual wildflower ranging from 10-40 cm in height with simple to freely branched stems. Its herbage is sparsely to densely covered with many short hairs and less numerous, longer brownish hairs. The leaves are compound palmate with 5-8 linear-oblanceolate leaflets with the individual leaflets 1.5-3 cm long. The upper leaf surfaces are hairless while the lower surfaces have appressed hairs (see leaf photos). The leaf petioles are longer than the individual leaflets.

The inflorescence is a very short raceme of several flowers which is raised above the leaves. Individual flowers range from 5-7 mm long and are found on short pedicels from 1-2 mm long. The calyx lobes are unequal in length but are roughly 3 mm long. The petals are blue and the banner is often white-centered. Violet spots may or may not be found in the white banner. The banner is roughly equal to the wings and only slightly reflexed above the wings. The brownish pods range from 2-3 cm long and are covered with appressed hairs. 5-7 seeds may be found within the pods.

Small-flowered lupine may be easily confused with Lupinus bicolor, but the latter species has flowers with the banner reflexed further backwards so the space between the banner and wings is more open. The flowers of the latter species tend to be slightly longer, ranging from 7-9 mm in length.


Habitat:

Small-flowered lupine is found growing in open prairies or gravelly areas at low elevations. It sometimes is very numerous on the sites where it is found, where it paints the ground blue when in bloom.


Range:

Small-flowered lupine is found west of the Cascade Mts. from British Columbia south to California and up the Columbia River to northeastern Oregon.

It may be found throughout the length of the Columbia River Gorge between the elevations of 100' to 1800' and its range extends east to northeastern Oregon.

 


The photo above shows a close-up sideview of the flower of small-flowered lupine. The banner is held forward, closely above the wings rather than reflexed upright as in the similar bicolor lupine (Lupinus bicolor). Photographed at Catherine Creek................May 14, 2006.

The dorsal surface of the palmately compound leaf of small-flowered lupine as seen from Catherine Creek..............May 14, 2006. Notice the largely glabrous dorsal surface of the leaflets, and the numerous spreading hairs on the ventral leaflet surface.

The ventral surface of the compound palmate leaf of small-flowered lupine as seen from Catherine Creek..............May 14, 2006. Notice the numerous long, spreading hairs on the ventral surface of the leaflets.

Small-flowered lupine at Catherine Creek.....................May 14, 2006.

Small-flowered lupine: Lupinus micranthus

Small-flowered lupine as seen at Catherine Creek in the Columbia River Gorge....................April 9, 2009.

Paul Slichter