| The genus Penstemon is made up of 250 species of deciduous, semi-evergreen, and evergreen perennials and subshrubs, and numerous cultivars which tend to be semi-evergreen. Leaves are narrow, up to 3 inches long, or large and ovate, to 5 inches long. Racemes or panicles of foxglove-like flowers are produced from early summer to mid fall.
'Powis Castle' bears deep reddish-purple flowers with purple-marked, white throats. |