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.

Author: The Morton Arboretum

This species was reported from Jasper and Lake Counties before our manuals recognized Linum medium var. texanum to which I believe both records should be referred. The Lake County specimen was collected by Hill, July 28, 1875, near Pine and is deposited in the herbarium of DePauw University. It is labeled Linum sulcatum but is Linum medium var. texanum. My specimens were collected on the low, moist, gravelly border of the north side of Wall Lake, Lagrange County; on the dry, gravelly bank of the St. Joseph River, St. Joseph County; and on the dry, gravelly, high bank of Big Wea Creek about 4 miles southwest of Lafayette, Tippecanoe County. Charles M. Ek found a colony along a railroad in Howard County. The only specimens from the southern part of the state are one collected by Clapp in Harrison County near Palmyra, July 14, 1836, which is now in the herbarium of Wabash College, and one which I collected in the same county on a post oak ridge about 5 miles southwest of Corydon.