This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Introduced. Biennial. Propagates by seeds.
Time of bloom: Late June to September.
Seed-time: August to October.
Range: Eastern and middle United
States and Canada. Habitat: Grain fields, meadows, and waste places.
This plant develops a thick, fleshy root, from which it sends up several slender, branching stems, one to two feet in height, somewhat hairy and viscid. Leaves long ovate to lance-shaped, the lower ones tapering to margined petioles, the upper ones smaller, acute, and sessile. Flowers in loose panicles, usually dioecious, numerous, white or often tinged with pink, fragrant, each about an inch broad, opening in the evening and closing after sunrise the next day; each of the five petals is deeply notched at the outer edge, and at the inner point is a pair of white, scale-like bracts, narrowing the throat of the flower which is fertilized by long-tongued, night-flying moths. Sterile flowers have usually ten stamens. Calyx of the fertile flowers much inflated, crimson-tinged along the hairy ribs. Styles five. Capsules onecelled large, ovoid, with ten inbent valves at the apex which curve outward when ripe and from which the seeds are shaken out as the winds sway the stems; seeds very abundant, small, grayish brown, beaded with fine tubercles; too frequent an impurity among those of grain, grass, and clover. (Fig. 97.)
Fig. 97. - White Cockle (Lychnis alba). X 1/3.
Prevent seed production by close cutting or hand-pulling at the time of first bloom. Meadows and grain fields where the plants have been permitted to distribute seed should be broken up and given a short rotation of cultivated crops before reseeding.