Penstemon may be deciduous or evergreen perennials or subshrubs, with simple, narrow leaves and racemes or panicles of bell-shaped or funnel-shaped flowers in summer and early autumn
'Catherine de la Mare' is a spreading, woody-based, semi-evergreen perennial to 50cm tall, with dull, bluish-green leaves and dense racemes of purplish-blue flowers 3cm long, borne on reddish stems in summer