Bluebonnets are now blossoming in Texas so I thought it would be a good time to try to explain the difference between a bluebonnet and a Wild Lupine (Lupinus perennis).
Texas bluebonnets are actually six different Lupinus species with only one having the official name of Texas Bluebonnet or Lupinus texensis. Bluebonnets grow in most southwestern states, while Wild Lupine grows in Wisconsin and most northeastern and southeastern states.
Although they are both in the Lupinus genus, they blossom at different times and, of course, in different climates. The shape of the petals of the Bluebonnet flower (raceme*) resembles the bonnets worn by pioneer women, hence the name. Typically blue in color, the flower florets also will grow in shades of white, pink, lavender, purple and maroon. Each floret has a wide white banner spot in the center of the banner petal. As the floret ages, this spot often turns reddish-purple. As the entire flower (raceme) ages, one of the top petals turns reddish-purple. It is considered ephemeral; it goes dormant by late spring.
According to Mike Quinn, past president of the Austin Butterfly Forum, “the bluebonnet is the larval food host for the Northern Cloudywing, Gray Hairstreak, Henry’s Elfin, Painted and American Lady, and Orange Sulphur butterflies.” (Wildflower.org)
Like the Texas Bluebonnet, Wild Lupine (Lupinus perrenis) likes well-drained soil and a sunny location. Wild Lupine, however, blooms late spring to early summer. It, too, is considered an ephemeral because it goes dormant by mid-summer. Its blooms, described as pea-like, are blue to violet in color and also have a white area at the tip of each floret.
Although the Wild Lupine is the only host plant for the Karner Blue butterfly caterpillar, a federally-endangered species native to the Great Lakes region, it is also a host plant for the Frosted Elfin and the Eastern Persius Duskywing butterflies.
Seeds and Leaves
All species of Lupinus have leaves which are palmate with anywhere from 3 to 11 leaflets. When seeds are ripe they spring from their pods with a popping sound. Before they can germinate, however, the seeds must be scarified (roughed up) to allow water uptake.
The bluebonnet and Wild Lupine belong to the Legume or Bean Family (Fabaceae or Leguminosae) which makes the plant a good source for nitrogren — a natural fertilizer. That is why plants of the Legume Family are able to grow so well in disturbed areas and often are used as a cover crop to enrich the soil.