Some Veronica species are highly attractive ornamental plants. And although the weedy species, commonly called speedwells, produce lots of pretty blue flowers, these creeping perennial plants can spread significantly and can smother other plants and take over the garden. They are particularly troublesome when they become established in lawns.
The two most troublesome weedy species are slender speedwell (Veronica filiformis) and Germander speedwell (Veronica chamaedrys).
Speedwells grow and root very quickly, soon producing quite large plants. They produce numerous creeping stems that root as they grow, soon spreading to form a dense carpet that can cover large areas of ground, getting out of hand and smothering other low-growing plants. Even small pieces of a plant will grow into larger ones.
In lawns, they can be very difficult to control.