22. Penstemon
Penstemon is the name of a large genus of flowering perennials that are mostly indigenous to the Nearctic climate of North America. This notion makes them an ideal hardy flower for northern gardeners who struggle to find colorful options for their gardens.
All varieties feature tubular flowers in a wide range of beautiful shades, with purples being the most common. Many types are desert hardy in addition to cold hardy so that they can thrive in many areas.