Veronica longifolia 'Eveline' : a lush carpet of purple spires

Veronica longifolia (speedwell, véronique à longues feuilles) is a Eurasian perennial bearing spikes of small purple (or blue, or white) flowers.

There are a few veronicas which are native to Ontario. They are not as flamboyant as the Eurasian veronicas sold to gardeners, but I think Veronica americana (American brooklime or American speedwell, véronique d'Amérique) and Veronica anagallis-aquatica (water speedwell, water pimpernel, mouron aquatique) have potential as water garden plants. Both have dainty blue flowers which some find reminiscent of forget-me-nots. In our garden, I'm encouraging the native volunteer Veronica serpyllifolia (thyme-leaf speedwell, véronique à feuilles de serpolet) as a groundcover.

There are also some unrelated natives with spires of purple flowers. I like Verbena stricta (hoary vervain, verveine veloutée), and Agastache foeniculum (lavender hyssop, hysope anisée), a mint-relative with a strong licorice scent.