There are a few plants which have an uncertain number of stamens, which constitute the class Dodecandria. Three are trees; one is the houseleek, which is hardly wild, and two (Asarum and Hornwort) are rarely found. The spurges (see p. 35) are placed here, together with the purple loosestrife (1 pistil), agrimony (2 pistils), and wild mignonette (3 pistils). The spurges are known by their milky juice and the peculiar shape of the flower. When one has been identified all the rest may be easily recognized. There are 2 species of agrimony, 3 of mignonette, and more than a dozen spurges. Purple loosestrife has its stamens of different lengths.