wall speedwell, rock speedwell
Corn speedwell is an upright, clumping winter annual that produces small purple flowers in the spring. The lower, non-flower, portion of the plant has leaves that are round-to-oblong with rounded teeth on the margin in an opposite arrangement. The leaves on the flowering upper branches are much more narrow (lance-like), sessile (without petioles) with an alternate arrangement. The fruit is a heart-shaped capsule containing numerous yellow seeds.
Corn speedwell does not typically persist very long after flowering. Attempts to control corn speedwell in the spring are usually unsuccessful because the plant is at the end of its lifecycle. Individual plants form 10cm patches. Heavy infestations can result from extended growing conditions in the fall and cool springtime temperatures.