Annual herb 15 cm - 0.8 m tall Stem: with grooved branches usually forming near the top of the plant. Leaves: mostly alternate, 1 - 3 cm long, linear, sometimes with a pair of tiny dark glands at the base. Flowers: borne on an inflorescence with ascending branches, with five yellow petals 5 - 12 mm long and 2 - 4.5 mm long styles that are united for 0.3 - 1.5 mm at the base. The five sepals are 3 - 7 mm long, broad lance-shaped with a pointed tip, glandular-toothed, and persistent. Fruit: 2.5 - 3.5 mm long, egg-shaped to nearly spherical with a rounded to pointed tip, splitting into ten erect-beaked sections.
Similar species: This is the only variety of Linum sulcatum in the Chicago Region.
Flowering: late June to late September
Habitat and ecology: Common in dry hill prairies.
Occurence in the Chicago region: native
Etymology: Linum is the Latin name for flax. Sulcatum means furrowed.