Tepal
Tepals are elements of the perianth, or outer part, of a flower. The perianth is composed of the petals and sepals. The term tepal is usually used when all segments of the perianth are of similar shape and color, or undifferentiated into petals and sepals. When the petals and sepals look the same they are called tepals
Undifferentiated tepals are thought to be the ancestral condition in flowering plants. Amborella, which is thought to have separated earliest in the evolution of flowering plants, has flowers with undifferentiated tepals. Distinct petals and sepals would therefore have arisen by differentiation, probably in response to animal pollination. In typical modern flowers, the first whorl of organs forms sepals, specialised for protection of the flower bud as it develops, while the second whorl forms petals, which attract pollinators.
In some plants the flowers have no petals, and all the tepals are sepals modified to look like petals. These organs are described as petaloid, e.g. the sepals of Hellebore.
Undifferentiated tepals are common in Monocotyledons. In tulips, for example, the first and second whorls both contain structures that look like petals. These are fused at the base to form one large, showy, six-parted structure. In lilies the organs in the first whorl are separate from the second, but all look similar, thus all the showy parts are often called tepals.
Usage of the term 'tepal' is inconsistently applied to some flowers by some authors, some refer to 'sepals and petals' of plants that have petal like sepals that can still be distinguished from petals by there placement with in the perianth while others use the word 'tepal' for those same sepals.
The word tepal is derived from a combination of the words petal and sepal.
The word tepal is derived from a combination of the words petal and sepal.
References
Botany: A Brief Introduction To Plant Biology - 5th ed. Thomas L. Rost; T. Elliot Weier - Wiley & Sons 1979 ISBN 0-471-02114-8.
Plant Systematics - Jones; Samuel - McGraw-Hill 1979 ISBN 0-07-032795-5.
- Flowers with tepals
