Lewis flax (Linum lewisii var. lewisii) is an uncommon, non-native, prairie wildflower. It is native to western North America as far east as North Dakota. It is uncommon in Minnesota where it is considered adventive—it is not fully established and the populations in the state may not be self-sustaining. The first recorded observation in Minnesota was in 1959. It continues to spread as it is often included in seed mixes used on prairie restorations.
Lewis flax is semi-evergreen, with at least some foliage remaining green throughout the winter. Flowers are not produced until the third year or, if conditions are favorable, the end of the second year. Bright blue flowers appear from May to July. The petals open at sunrise and fall off by late afternoon.