Mexican petunia (Ruellia brittoniana)
Like the Turk’s cap, Mexican petunia loves hot, hot weather. Spiky 3’-4’ stalks covered in lance-shaped dark green leaves are topped with 1”-2” purple, pink or white funnel-shaped flowers. ‘Katie’s Dwarf’ stays in the 6"-12” range if you want something more well-behaved. Likes water--it’s an aquatic in Mexico, but will take drought and reseed freely once it gets going. Will grow in some shade but flowers freely more in sun.