This summer, after another exceptionally hot July, I have found myself increasingly impressed by the plants that simply take heat and drought in their stride and don't need supplemental watering. I've always had a soft spot for silver-leaved plants such as santolina and lamb's ear, which seem to relish the conditions that leave other perennials struggling.
Of course, there is no such thing as a plant you can put in the ground and literally never water. Every shrub and perennial will need some care while establishing, particularly during its first and even second year. But after a few growing seasons, there are many species that can survive perfectly happily on rainfall alone, even during prolonged dry spells.
