Corn speedwell is a clump-forming annual native of Europe, Africa, and Asia where it grows in disturbed areas such as garden, lawns, pastures and waste places. It and is a member of the plantain family, Plantaginaceae, that also includes foxgloves, turtlehead and snapdragon. Corn speedwell is wide spread across the US growing in areas with full sun and medium moist to dry lean soil where competition from other plants is minimal.
Description: Corn speedwell grows two to eight inches high and has one to several unbranched slender stems that are light green and hairy. The lower leaves are opposite, l/8 inches wide, triangular to ovate, and have toothed margins and short petiole. The upper leaves are alternate, more linear, sessile, and have slightly toothed margins. All the leaves are light green and hairy. The pale blue flowers appear in mid-spring to mid summer in the axils of the upper leaves. They have four petals, four hairy sepals, and are 1/8th inch across. The heart-shaped seed capsules contain many small seeds and the plant tends to reseed itself. The root system is a much branched taproot.
Control: Since corn speedwell is an annual that spreads by reseeding the best way to eliminate it is by removing the plant before it flowers and sets seed. This can easily be done by hand pulling. Mulching or establishing a dense ground cover of grass or other plant will suppress further invasion. If corn speedwell covers a large area a pre emergent herbicide can be used in fall to prevent the seeds from germinating. Once corn speedwell appears in the spring a post emergent herbicide an be effective is used in early when growth is vigorous.