Veronica serpyllifolia: foliage and flowers

Veronica serpyllifolia, known in English as "thyme-leaf speedwell" and in French as véronique à feuilles de serpolet is a small, creeping perennial native to much of North America. It is one of a number of small veronicas that grow wild in Toronto, some native and some alien; I identified this one as V. serpyllifolia based on the leaf shape. Here's an attempt to get a better look at one of the flowers (click to enlarge). The veronicas have four petals, with the bottom petal being smaller than the others. V. serpyllifolia is usually white with dark blue stripes, but may also be light blue or white, like this one.

Although the Ontario government considers this a weed, I think it's rather dainty. I'm going to see if it will spread enough to act as a ground cover between the more showy plants.