Flower:

Drooping panicle or multiple racemes of stalked flowers at branch tips. Flowers are up to ~1½ inches diameter with 5 broad petals each 10 to 23 mm long, bright blue to blue-violet, usually white or yellowish at the base. In the center are 5 white-tipped stamens surrounding 5 styles about as long as or longer than the stamens, each style with a small ball-like tip.

The 5 sepals are elliptic to egg-shaped, usually pointed at the tip, hairless, and green with a papery translucent edging. Flower stalks are slender and smooth, drooping in bud, becoming erect at flowering and may droop again in fruit. Flowers open in early morning, the petals falling away by noon.

Leaves and stems:

Leaves are erect to ascending, alternate but may appear whorled on the lower stem, up to about 1 inch (3 to 30 mm) long, less than ¼ inch wide, lance-linear, pointed or blunt at the tip, 1-nerved, stalkless, toothless and hairless, becoming smaller as they ascend the stem. Stems are multiple from the base, mostly erect or ascending but sometimes sprawling, branching near the base or just towards the top, leafy, round in cross section, hairless and smooth. 

Fruit:

Fruit is a round capsule about 1/3 inch (4 to 8 mm) long, straw-colored at maturity, the sepals persistent but withering. The capsule splits from the tip into 10 wedge shaped sections, each with 1 or 2 dark brown to black seeds that become slimy when wet.

Notes:

Blue Flax reaches the eastern edge of its range in Minnesota, where it is occasionally encountered in some of our western counties in road ditches and prairie remnants, or in restoration plantings elsewhere. Two other blue flaxes can also be found here in Minnesota. Common flax (Linum usitatissimum) is a Eurasian species that is cultivated for its fiber, edible seeds and oil. Escaped plants can come from any number of sources including mud from commercial grain trucks, and backyard bird feeders. It is an annual that typically is unbranched, sepals have a fringe of hairs around the edge (ciliate), and leaves are 3-nerved.

Perennial/Garden Flax (Linum perenne), native to Europe and Asia, is sold in the garden trade and is commonly included in seed mixes. It is so similar to L. lewisii that some references treat our native as a variety of it. The most consistent difference is that the styles of Perennial Flax flowers are what's known as heterostylic, with some plants in a population having short stamens with longer styles and others with short styles and longer stamens, where the native Blue Flax has styles all the same length (homostylic). Descriptions of some other characteristics are inconsistent across references so it's difficult to recommend any that are reliable in the field.

While Perennial Flax has been known to escape cultivation, its distribution in Minnesota is murky; of the handful of collections, at least some are possible hybrids. Having seen confirmed Perennial Flax in cultivation, I now have to question our own sightings of the native Flax and will pursue this further in the coming seasons.

There are 3 recognized varieties of L. lewisii; var. lepagei is restricted to the Hudson Bay area of Canada and has mostly white flowers, var. alpicola is restricted to alpine regions of the SW US and is essentially a dwarf; var. lewisii is found mostly west of the Mississippi River, including Minnesota, and is as described above.