When it is difficult to distinguish between the components of the perianth, such as when the petals and sepals are the same colour or when the petals are absent and the sepals are colourful, the term "tepal" is used to refer to the perianth component in question. They are also referred to as lilioid monocots because they include Liliales in their classification. Plants belonging to genera such as Aloe and Tulipa are examples of those that can be referred to as having tepals.