There are about 4 million species of flowering plants and all their flowers, irrespective of how pretty they look, have the same function. Flowers are the reproductive parts of an angiosperm plant. They are designed to be attractive in size, colour, form, and scent to facilitate pollination.
The reproductive organs within a flower are called stamen and pistil. Most flowers are bisexual and have both functional pistil and stamens. Some flowers are unisexual and have either stamens or pistils. A plant bearing both male and female flowers is called monoecious, while there are dioecious plant species that bear male flowers and female flowers in separate plants. Staminate flowers only have male reproductive parts and similarly, flowers with only female reproductive parts are also called pistillate.
When we look at flower parts, we describe them as whorls. The outermost whorl is the calyx consisting of the sepals. It is typically for the protection of buds and support. Within it comes the second whorl called corolla made of petals. Further, inside is the third whorl called androecium, which is a group of stamens. The innermost whorl is the gynoecium consisting of pistils.
The names pistil and carpel are often used interchangeably, but they actually refer to different parts of a flower. A carpel is a part of the pistil that comprises the style, stigma, and ovary. In the pistil, the carpel is the ovule bearing leaf-like part extending out to the style. A pistil can have a single carpel (simple pistil) or several carpels (compound pistil). The carpels can even be fused or free. A gynoecium with a single carpel is called monocarpous. When there are multiple free carpels in a pistil, it is called apocarpous, and when these multiple carpels are fused, it is called syncarpous.
Within the pistil are the carpel's parts, such as the ovary, stigma, and style. For reproduction, the pollen grain produced on another part of the stamen must come in contact with the stigma. This happens through pollination. It can happen within the same flower (self-pollination) or across different flowers (cross-pollination). Following pollination, the pollen grains are transferred to the ovary where fertilization occurs. Thereby, the male gametes and the ovules are fused to form the zygote. The zygote develops into an embryo, and further-on the ovules become seeds, and the ovary becomes a fruit.
The below table is provided to highlight the comparison of pistil vs. carpel.
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The latest research suggests that the world's biggest and rarest flower, Rafflesia, may not have pistils. There is also no significantly identifiable ovary or carpel-like parts in it. They are identified as unisexual flowers, and the male flowers have several small stamens in the central disc-like structure that looks like spikes. The Rafflesia and similarly large, rare Corpse flower (Titan arum) are also the world's smelliest flowers. They smell like rotten meat. They are also extremely rare and bloom in colonies of same-sex flowers for a very short period. Therefore, these flowers need to pollinate successfully within a short time for the survival of the species. Their extremely unpleasant smell not only wards off predators but also attracts pollinators such as dung beetles and carnivorous flies, which are in search of corpses. This way, they can ensure successful pollination despite the distance between the colonies of male and female flowers.
1. What is carpel in flowers like jasmine?
Flowers like jasmine have very few ovules and short filaments for stamens. The carpels and stamens are also not developed at the same time. In such cases, self-pollination cannot occur. Even flowers like tulips have very few stamens and short pistils, so they are not readily visible.
Some flowers may not have ovaries that are readily visible. Such flowers are said to have inferior ovaries attached below the other floral parts and are called epigynous. In such flowers, the rest of the carpel and stigma may still be superior to the stamen. The thalamus of such flowers is flask-shaped. Flowers like orchids, bananas, apples, and melons are epigynous. The type of flower where the ovaries and carpel are superior to the stamen is called hypogynous. Tulips, mustard, and tomatoes have hypogynous flowers. Their thalamus is conical in shape. There are also perigynous flowers where the stamen, petals, sepals surround the ovaries, and the thalamus is disc-like. Prunes, cherry, rose, and plums are all formed from perigynous flowers.
2. Which of the carpel or pistil develops into a fruit?
When a flower is successfully pollinated, and the pollen has fertilized the ovules, it becomes a zygote. This zygote undergoes cell differentiation to become an embryo. The embryo attaches to the ovary, and it swells to become a fruit. Therefore fruit is a swollen form of the ovary, and the seeds in the fruit are the fertilized ovules. The carpels also develop to join the fruit tissue along with the ovary.
The number of carpels in the flower determines the degree and how much pollination the flower is required for the development of a fruit. Flowers with single carpels would require one of the two ovules to be fertilized to develop into a fruit. For flowers with multiple fused carpels, the fertilization of fewer ovules will also lead to fruit formation. In the case of almonds, walnuts there are only single carpels, whereas fruits like apples and Kiwis contain multiple carpels.