CISTUS, in botany, a genus of the polyandria monogynia class. The corolla consists of five petals, and the calix of five leaves, two of them being less than the other two. The species are 37, and only five of them natives of Britain, viz. the guttulos, or annual cistus; the helianthemum, or dwarf cistus, or sun-flower; the surreianus, or narrow-leaved cistus; the polii-folius, or mountain dwarf cistus; and the hirtus, or hoary dwarf cistus.