Sand Penstemon, Penstemon anbiguus, is not your every day penstemon species. For the Tucson and Green Valley areas, use this lovely 3 foot tall and wide shrub in your landscaping where it will receive excellent drainage.
This plant does not look like most penstemons, but certainly is one worth considering. The plant forms a somewhat woody mound of bright green leaves. The pale pink flowers appear in the summer, extending the bloom time by blooming after those penstemon species that bloom in early spring. Since it is deciduous, plant in a location where its dormancy is not noticeable.
Since this plant is native to the southwest at higher elevations, afternoon shade will probably be a good idea, even though Mountain States Wholesale Nursery recommends full sun. Plants adapted to higher elevations often suffer in lower elevations if they receive hot afternoon sun.
Reference: Mountain States Wholesale Nursery and Gregg Starr Nursery Plant Info Sheet, 1999.