Linaria purpurea "Canon J. Went," also known as perennial Toadflax, is one of my favorite perennials, not only for the spikes of delicate pink (sometimes lavender) blooms, but also for the soft, silvery-grey foliage.  My experience with Linaria purpurea is that it is not particularly long-lived, but it reseeds and, like foxglove, it is rare to be without it somewhere in the garden.  Linaria purpurea "Canon J. Went" grows from two to four feet tall and likes sun/part shade in Zones 5-8.  Quarts.