Annual herb to 1 m tall Stem: erect, one to several. Leaves: many, 1.5 - 3.5 cm long, lance-linear, three-veined. Flowers: borne on a loose terminal inflorescence, having five sepals 7 - 9 mm long with a pointed tip and five blue petals 10 - 15 mm long. The inner sepals are toothed and minutely hairy along the dry papery margin. Fruit: a capsule, 6 - 10 mm long, nearly spherical and abruptly short-beaked, incompletely splitting into ten segments with pointed tips.
Similar species: Linum perrenne and Linum usitatissimum both have blue petals and wider fruit (5 - 10 mm) than the other Linum species in our region. Linum perenne differs by its perennial life cycle, multiple stems, toothless and hairless sepals, and leaves that are single-veined or three-veined only near the base.
Flowering: late May to mid October
Habitat and ecology: Introduced from Europe and cultivated for seed and fiber, this species grows near grain elevators and railroad ballasts or in waste ground.
Occurence in the Chicago region: non-native
Etymology: Linum is the Latin name for flax. Usitatissimum means "most useful."
Annual; stems 1-several, erect, to 1 m; lvs lance-linear, 3-nerved, 1.5-3.5 cm; sep 7-9 at maturity, the inner minutely ciliate on the scarious margin; pet blue, 10-15 mm; staminodes minute, tooth-like; stigmas linear-clavate; fr 6-10 mm, subglobose and abruptly short-beaked, tending to be only tardily and incompletely dehiscent, the mericarps acuminate; false septa very incomplete, long-ciliate; 2n=30. European cultigen, often escaped or adventive in fields and roadsides in U.S. and s. Can. Summer. (L. humile)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Wiggins 1964, Jepson 1993, Kearney and Peebles 1969
Duration: Annual Nativity: Non-Native Lifeform: Forb/Herb General: Erect or ascending introduced annual to 80 cm tall with striate, lightly angled stems. Leaves: Linear-lanceolate, sessile leaves, 1-3 cm long; entire, generally glabrous; bracts similar to leaves but 1 cm long or less. Flowers: Pedicels subfiliform to 3 cm long, outer sepals elliptic to lanceolate, inner sepals ovate, 5-6 mm long in flowers, 7-9 mm in fruit, papery-hyaline near margins; petals blue, 1-1.5 cm long; styles distinct or essentially so. Fruits: Capsule broadly ovoid, 8-11 mm high with light brown, smooth and shining seeds, 4-5 mm long. Ecology: Found in disturbed areas; flowers March-April. Notes: Distinguished from the native L. lewisii by virtue of being an annual. Ethnobotany: Taken as a cough medicine for violent coughs or colds, for fevers, and other diseases of the lungs. Etymology: Linum comes from the Greek name for flax linon, while usitatissimum comes from the Latin usitatus, or customary, common, or familiar. Synonyms: Linum humile, Linnaeus usitatissimum var. humile Editor: SBuckley, 2010