en Slender speedwell
Veronica filiformis is a species of flowering plant in the genus Veronica. It is known by many common names, including slender speedwell, creeping speedwell, threadstalk speedwell and Whetzel weed. It is native to eastern Europe and western Asia, and it is known in many other regions as an introduced species and a common weed.
It reproduces asexually by resprouting from separated sections of stem and rhizome and easily takes hold in new habitat. The plant was originally used as groundcover in gardens and valued for its pretty blue flowers, but it is easily dispersed into the environment if it is chopped up, during mowing, for example. It is still cultivated, sold, and used in gardening. (source: Wikipedia)