There are over 70 lupine species in California alone, many of which are difficult to identify. Miniature lupine (also known as bicolor lupine) is a small plant with flowers that are approximately 1/4 inch long, a big help in identification. Although even this little lupine has more than eight subspecies and varieties. Miniature lupines (Lupinus bicolor) rarely grow more than a foot in height.
A native annual (sometimes it can live for two seasons), miniature lupine grows in diverse habitats below 4,500′ where there is thin or disturbed soils. It is found in British Columbia, Washington, Oregon, California and Arizona.
Miniature lupine has several stems growing from a base. The stems may be branching or simple. The entire miniature lupine plant is villous (bearing long, shaggy hairs).
The alternate leaves of miniature lupine are palmately compound and have 5 to 7 leaflets and are hairy on both the upper and under surface.
The pea-like miniature lupine flowers grow in a raceme at the end of the stems. The flowers are blue-purple with a large white spot bearing purplish markings on the banner petal. This white spot becomes pinkish-purple after fertilization (hence the common name and species designation bicolor). There are 10 stamens. The wing petals curve to partially cover the banner petal.
The fruit of miniature lupine is a small, hairy pod bearing 5 to 8 tiny, pea-like, brownish seeds.
Bees and hummingbirds are miniature lupine pollinators. The foliage is also a food source for orange sulfur butterfly larvae and several species of blue butterfly larvae (caterpillars). This pretty little plants is also widely cultivated as an ornamental.
Lupus is the Latin word for wolf. The genus name, Lupinus, was given to lupine plants because they were originally thought to rob the soil of its fertility. This belief is incorrect because lupines (or the bacteria on their roots – another post?) fix atmospheric nitrogen into a useful form enhancing soil fertility.
These miniature lupines were growing along the Pacific Crest Trail above Baum Lake (Shasta County CA) and photographed in late April and early May.