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In a mature flower, the perianth consists of a calyx (sepals) and the corolla it supports. A sepal (/ ˈ s ɛ p əl, ˈ s iː p əl /) [1] [2] [3] is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom. [4]
Instead, a typical angiosperm flower possesses verticils or ordered whorls that, from the outside in, are composed first of sterile parts, commonly called sepals (if their main function is protective) and petals (if their main function is to attract pollinators), and then the fertile parts, with reproductive function, which are composed of ...
The B function allows the differentiation of petals from sepals in the secondary verticil, as well as the differentiation of the stamen from the carpel on the tertiary verticil. Goethe 's foliar theory was formulated in the 18th century and it suggests that the constituent parts of a flower are structurally modified leaves, which are ...
For example, when there is a loss of B gene function, mutant flowers are produced with sepals in the first whorl as usual, but also in the second whorl instead of the normal petal formation. In the third whorl, the lack of the B function but the presence of the C function mimics the fourth whorl, leading to the formation of carpels also in the ...
The genetics behind the formation of petals, in accordance with the ABC model of flower development, are that sepals, petals, stamens, and carpels are modified versions of each other. It appears that the mechanisms to form petals evolved very few times (perhaps only once), rather than evolving repeatedly from stamens.
If the hypanthium is absent, the flower is hypogynous, and the stamens, petals, and sepals are all attached to the receptacle below the gynoecium. Hypogynous flowers are often referred to as having a superior ovary. This is the typical arrangement in most flowers. If the hypanthium is present up to the base of the style(s), the flower is ...
The petals and sepals are above the ovary; such a flower is said to have an inferior ovary, or the flower is said to be epigynous. Cross section of a tulip ovary. In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium.
A floral diagram is a graphic representation of the structure of a flower. It shows the number of floral organs, their arrangement and fusion. Different parts of the flower are represented by their respective symbols. Floral diagrams are useful for flower identification or can help in understanding angiosperm evolution.