Perennial herb 15 cm - 0.8 m tall Stem: one to several from base, unbranched below the inflorescence. Leaves: opposite near base, becoming alternate above, mostly ten to 40 below the inflorescence, 1.5 - 2.5 cm long, 3 - 6 mm wide, elliptic-lance-shaped to narrow oblong with the lower leaves often inversely egg-shaped. A single narrow wing continues down the stem, but does not reach the leaf below. Flowers: borne scattered on an open inflorescence with few wiry ascending-spreading branches, with five yellow petals 3.5 - 5.5 mm long. The five sepals are 2 - 4 mm long, lance- to egg-shaped, toothless, with the outer ones having pointed tips and the inner ones shorter and often having a few tiny stalkless glands along the margins. Fruit: a capsule, about 2 mm long, flattened at both ends or depressed-spherical, splitting into ten segments which fall early.
Similar species: Linum intercursum, Linum medium var. taxanum, Linum striatum, Linum sulcatum, and Linum virginianum have yellow petals and smaller fruit than the other Linum species in our region. Linum sulcatum is an annual with gland-toothed outer and inner sepals, styles that are united near the base, and leaves with a pair of glands at the base. Linum striatum has a prominently ridged stem and an elongate inflorescence, L. intercursum has a narrow-tipped capsule, and L. medium has stiffly erect inflorescence branches and 30 to 150 leaves below the inflorescence.
Flowering: early July to late August
Habitat and ecology: Rare in woods.
Occurence in the Chicago region: native
Etymology: Linum is the Latin name for flax. Virginianum means "from Virginia."
Author: The Morton Arboretum
From Flora of Indiana (1940) by Charles C. Deam
Infrequent in open places on the crests and slopes of black and white oak and chestnut oak ridges in the southern part of the state; in prairie habitats in the northern part of the state; and in dry, open, white oak and white and black oak woods elsewhere.
Glabrous perennial 2-7 dm; stems 1-several from the base, simple below the infl; lvs mostly 10-40 below the infl, elliptic to oblanceolate or obovate, 1.5-2.5 cm נ3-6 mm, the lower opposite, the upper often alternate; stem with a single narrow wing decurrent from the base of each lf but not extending to the lf below; infl open-corymbiform, typically with a few rather long, slender, ascending-spreading branches; pedicels 2-8(-10) mm, terete or nearly so; sep lance- ovate, the outer acute, entire, 2-4 mm, the inner shorter, broader, often with a few tiny sessile glands along the margins; pet yellow, 3.5-5.5 mm; fr depressed-globose, scarcely 2 mm, readily splitting into 10 mericarps, shattering and falling; false septa nearly complete, glabrous; true septa usually sparsely ciliate; 2n=36. Upland woods; Mass. and s. Ont. to s. Mich., n. Ill., and Mo., s. to Ga. and Ala., southward mostly avoiding the coastal plain. June, July. (Cathartolinum v.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.