8.1: Flower Anatomy
- Page ID
- 35351
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Flowers are composed of many distinct components: sepals, petals, stamens, and carpels. These components are arranged in whorls and attach to an area called the receptacle, which is at the end of the stem that leads to the flower. This stem is called the peduncle. In the case of an inflorescence, where multiple florets are produced in place of a single flower, the stems leading to the florets are called pedicels.
![Long section through a lily showing floral anatomy](https://bio.libretexts.org/@api/deki/files/27330/Flower_Anatomy.png?revision=1)
![A sketch that labels the components of the inflorescence described in the other image](https://bio.libretexts.org/@api/deki/files/29989/InkedUntitled-1_LI.jpg?revision=1&size=bestfit&width=336&height=435)
Whorls
Flowers are composed of sets of highly modified leaves arranged in whorls. The outermost whorl of a flower is called the calyx and is composed of sepals. Inside the calyx is the corolla, which is composed of petals. The sepals are often smaller and less colorful than the petals, but this general rule can be misleading. For example, lilies often have identical sepals and petals. The only way you can distinguish between them is by location: Which whorl is on the outside?
Together, the calyx and corolla are called the perianth (peri- meaning around, anth- meaning flower).
The Perianth: Calyx and Corolla
![A closed buttercup flower](https://bio.libretexts.org/@api/deki/files/26900/Calyx_and_corolla.jpg?revision=1&size=bestfit&width=435&height=517)
![A flower that has been cut in half and is being held down by a sharp probe](https://bio.libretexts.org/@api/deki/files/26895/Floral_anatomy_3.jpg?revision=1)
Reproductive Parts: Androecium and Gynoecium
![A flower that has been cut in half and labeled](https://bio.libretexts.org/@api/deki/files/26896/Floral_anatomy_unlabelled.jpg?revision=1&size=bestfit&width=440&height=552)
Inside the perianth is the androecium (house of man), a whorl composed of stamens. Each stamen has a long filament holding up pollen sacs called anthers. Inside the androecium is the gynoecium (house of woman), which is composed of carpels. Each carpel has an ovary at the base where ovules are housed. The style emerges from the ovary and is topped by the stigma. Pollen grains land on the stigma and must grow a tube down the style to reach the ovule and complete fertilization.
![A long section through a flower with the gynoecium labeled](https://bio.libretexts.org/@api/deki/files/26893/49705911957_f72e867531_c.jpg?revision=1&size=bestfit&width=326&height=580)
![A long section through a flower with the androecium and ovary labeled](https://bio.libretexts.org/@api/deki/files/26894/Floral_anatomy_2.jpg?revision=1&size=bestfit&width=373&height=579)
Androecium: The Stamen Whorl
![A buttercup with many stamens that has dispersed pollen on a nearby blade of grass](https://bio.libretexts.org/@api/deki/files/26901/Ranunculus_anatomy.jpg?revision=1&size=bestfit&width=655&height=492)
![A single stamen with the anther and filament labeled](https://bio.libretexts.org/@api/deki/files/26897/floral_anatomy_stamen.jpg?revision=1&size=bestfit&width=501&height=511)
![Reproductive parts of a flower under the microscope](https://bio.libretexts.org/@api/deki/files/26898/floral_anatomy_pollen.jpg?revision=1&size=bestfit&width=444&height=577)
![A close up on the pollen](https://bio.libretexts.org/@api/deki/files/26899/Floral_anatomy_pollen_2.jpg?revision=1&size=bestfit&width=451&height=573)
Gynoecium: The Carpel Whorl
![The androecium and gynoecium of a Trillium flower with parts in sets of 3](https://bio.libretexts.org/@api/deki/files/26902/Trillium_anatomy.jpg?revision=1&size=bestfit&width=583&height=437)
![Anatomy of a flower](https://bio.libretexts.org/@api/deki/files/45595/2560px-Mature_flower_diagram.svg.png?revision=1&size=bestfit&width=870&height=502)
![A gynoecium with a single ovary and three styles. The cross section is a single ovary with 6 ovules.](https://bio.libretexts.org/@api/deki/files/42223/Gynoecium_morphology_fusion_syncarpous_carpels_3_locules_1.png?revision=1)
![A gynoecium with one ovary, style and stigma. The ovary cross section has 5 compartments, each with a pair of ovules.](https://bio.libretexts.org/@api/deki/files/42224/Gynoecium_morphology_fusion_syncarpous_carpels_5_locules_5.png?revision=1)