Spires of tubular flowers of blue, stained purple, help Penstemon ‘Stapleford Gem’ stand out in the garden. The flowers share a pout with the thicker petals of foxgloves, but have more of a luminescent quality. Purple beelines draw our eyes down the pale throat into the flower.
Some very reputable UK nurseries are selling this plant by the name of Penstemon ‘Sour Grapes’ but the RHS advises us that this is a misnomer.
Shared for Cee’s Flower of the Day
Susan Rushton 
Beautiful – it’s my favourite penstemon. (And it’s great to know the correct name so that I can buy a replacement for the plant I had years ago. 🙂 )
Perhaps it is a case where you might want to see the plant in flower before you take the plunge, just to be on the safe side. 🙂
Mind you, if you’re like me, you’ll probably like them all, just to a greater or lesser degree.
That’s the problem for me…I like too many and haven’t the space for all of the plants I’d like!