Tepals are elements of the perianth, or outer part of a flower, which include the petals or sepals. The term tepal's usually used when all segments of the perianth are of similar shape and color, or undifferentiated. When different types of organs can be distinguished, they're referred to as petals and sepals. Undifferentiated tepals are thought to be the ancestral condition in flowering plants. Amborella, which's thought to have separated earliest in the evolution of flowering plants, has flow… (More on Tepal)