Flower:

Loose clusters of stalked flowers at the tips of branching stems in the upper plant. Flowers are ¾ to 1 inch across, pale blue to bright blue-violet or occasionally white, with deeper blue radiating from the center, 5 spreading, broadly oval to wedge-shaped petals, widest above the middle, the tips rounded to nearly straight across and often a bit ruffled or ragged around the edge. The center is white with a green ovary, a column of 5 styles at the summit and surrounded by 5 erect, blue-tipped stamens.

The 5 sepals are lance shaped with sharply pointed tips, 3 nerves, and are hairless except for a fine fringe of hairs (ciliate) along the inner edge. Flower stalks are slender and smooth, ¼ to ½ inch long, erect from bud to open flower but may droop in fruit. Flowers open in early morning and usually close by noon.

Leaves and stems:

Leaves are nearly erect to ascending to spreading, alternate, ½ to 1½ inches long, about 1/8 inch wide, lance-linear, 3-nerved, stalkless, toothless and hairless, becoming smaller into the flowering branches. Stems are single or multiple from the base, erect, mostly unbranched except in the flower clusters, the branches ascending. Stems are leafy, round in cross section, hairless and smooth throughout. 

Fruit:

Fruit is a round capsule about 1/3 inch in diameter, the surface glossy, the persistent sepals longer than the capsule. The capsule splits from the tip into 10 wedge shaped sections, each with 1 or 2 brown seeds.

Notes:

Common flax is a Eurasian species that is cultivated for its fiber, edible seeds and oil. While not common or appearing to persist, escaped plants can come from any number of sources including mud from commercial grain trucks, and backyard bird feeders. Two other blue flaxes can also be found here in Minnesota.  Garden flax (Linum perenne) is also a European species found mostly only in cultivated gardens or nearby. The other a western US native Blue Flax (Linum lewisii) is only occasionally found along roadsides or restoration plantings and also planted in gardens. These two species are so similar they can only be distinguished from each other by the lengths of their styles. They differ from Common Flax in being perennial, more heavily branched, the leaves only 1 nerved, and sepals lacking the fringe of hairs.