So underused it doesn’t even have a decent common name! 

Leptodermis oblonga is a real beauty in the landscape and really deserves a little recognition!  The particulars:

• 18-24” tall x 3-4’ wide
• Masses of flower buds form in May, opening late in the month to 1” long, tubular, deep-purple flowers that nearly obscure the foliage
• Main bloom lasts for 4-6 weeks, but new growth on the plant will give rise to flowers throughout the summer and into the fall
• Has a dense, rounded shape that neatly spreads and is perfect for grouping