Calyx Information
The calyx is a collective term that refers to the outer layer of sepals that surrounds and protects the flower, both when it is still in the bud and after the flower has bloomed. Within the flowering plants the structural diversity of the calyx is quite large, for it may vary in shape from a large fused tube to very small whorl of thin green leaves.
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Fused or Non-fused
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One of the first things to examine in the calyx of the flower is whether the sepals are free forming or whether they are fused into one unit. Flowers with fused sepals are classified as gamosepalous, while those that have free standing sepals are called polysepalous flowers. Sometimes fused sepals can form a trumpet-like structure that is showy and colorful, such like those found in the myrtle family.
Protects The Bud
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In the early stages of flower development the leaf-like sepals will wrap around the flower bud in order to provide extra protection to to the developing flower parts. The petals which are located just inside the sepals may also perform the same task, thus adding a little extra protection to the male and female parts.
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Tepals
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The collective parts of the calyx and the corolla is referred as a perianth. Sometimes the petals and sepals within the perianth are indistinguishable. If this is the case each unit of the whorl is referred to as a tepal. Some of the flowers that have tepals are the tulip, anemone, magnolia and hellebore. Flowers that do not have differentiated petals and sepals are generally considered to be further back in the evolutionary chain.
Photosynthesis in Sepals
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If the sepals are green, they usually contain chlorophyll and will undertake the photosynthesis process to help create usable sugar energy to help the plant grow. This function of the sepals is most common in the more evolutionary developed plants like the sunflowers and the daisies.
Bracts
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The bract is a specialized leaf that grows near or at the base of the flower. Often a bract will protect the flower during the budding stage. In some of the grasses the bract forms a spathe that protects the small spike of flowers. It is also possible for the bract to appear like it is part of the flower. This situation occurs with red leaves of the poinsettia and the white leaves that surround the dogwood flower. In both cases the colorful leaves are bracts.
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References
- Photo Credit Finished blooming. image by firsov from Fotolia.com
