Carpel and Pistil: Structure, Function, and Comparison
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, color, 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.
What is a Carpel in a Flower?
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.
Difference Between Carpel and Pistil
The below table is provided to highlight the comparison of pistil vs. carpel.
Did you Know?
The latest research suggests that the world's biggest and rarest flower, Rafflesia, may not have pistils. There are 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.
The reproductive parts of a flower of a plant are called carpel and pistil, and they differ only slightly. Because a carpel is made up of the stigma, style, and ovary, and a pistil is made up of the union of carpels of a single carpel, we may say that a pistil is a fusion of carpels.
The number of carpels can be easily distinguished by counting the styles. The existence of ovaries in flowers, on the other hand, can be used to determine the number of pistils.
The flower is the reproductive component of a plant and represents the angiosperms family. A whole flower has unique reproductive structures that are colored and structured in a certain way. A flower has four whorls: lower whorls, middle whorls, and top whorls.
The reproductive whorls are the two upper whorls that are involved in reproduction. Also, these whorls are made up of microsporophylls and megasporophylls, with microsporophylls being called stamens and megasporophylls being called carpels (angiosperms).
The two bottom whorls are known as accessory whorls since they do not actively assist in the flower's reproduction. The third whorl is the male whorl, called androecium, and the fourth whorl is the female whorl, called gynoecium. The auxiliary pistil protects the vital organs and, more importantly, attracts pollinating insects.
Angiosperm is an area of science concerned with the study of blooming plants, flowers, and other Angiosperm attributes. We will look at the key differences between the two primary sections of the flower, the carpel, and the pistil, as well as a brief description of each.
FAQs on Difference Between Carpel and Pistil: Complete Guide
1. What are the fundamental roles of a carpel and a pistil in a flower?
In a flower, the carpel is the basic unit of the female reproductive organ, which contains the ovary, style, and stigma. Its primary role is to produce and protect the ovules. The pistil represents the entire female reproductive structure of the flower. It can be composed of a single carpel (a simple pistil) or multiple carpels fused together (a compound pistil). The pistil's function is to receive pollen, facilitate fertilization, and develop into a fruit containing seeds.
2. What is the main difference between a carpel and a pistil?
The main difference lies in their structural composition. A carpel is an individual, fundamental unit, while a pistil is the complete structure that may be formed from one or more carpels. Essentially, all pistils are made of carpels, but not all pistils consist of just one carpel.
- Carpel: A single structural unit comprising an ovary, style, and stigma.
- Pistil: The entire female organ, which can be either one single carpel or a fusion of multiple carpels.
3. How many carpels can a single pistil have?
A single pistil can have one or more carpels. This determines the type of pistil:
- Simple Pistil: Formed from a single carpel. This condition is called monocarpellary. An example is a pea flower.
- Compound Pistil: Formed from the fusion of two or more carpels. This condition is called multicarpellary. An example is a tomato or hibiscus flower.
4. Which part of the flower actually develops into the fruit after fertilization?
The ovary, which is the swollen basal part of the carpel (and therefore the pistil), develops into the fruit after successful fertilization. The ovules contained within the ovary develop into seeds. The rest of the carpel structure, like the style and stigma, typically withers away as the fruit matures.
5. How are the terms gynoecium, pistil, and carpel related to each other?
These three terms describe the female reproductive parts of a flower in a hierarchical way. The gynoecium is the collective term for all female reproductive organs in a single flower. The gynoecium is composed of one or more pistils. Each pistil, in turn, is composed of one or more carpels. Therefore, the carpel is the fundamental building block of the pistil, and the pistil is the structural unit of the gynoecium.
6. Are the terms 'carpel' and 'pistil' simply interchangeable?
No, they are not always interchangeable, which is a common point of confusion. The terms are only interchangeable when the pistil is a simple pistil, meaning it is formed from a single carpel. In this case, the pistil is the carpel. However, in flowers with a compound pistil (made of multiple fused carpels), the term 'pistil' refers to the entire fused structure, while 'carpel' refers to each of the individual units that make it up.
7. What is the significance of 'apocarpous' and 'syncarpous' conditions in flowers?
These terms describe the state of the carpels within the gynoecium and are significant for understanding flower structure and fruit development:
- Apocarpous: This condition occurs when a flower has multiple, separate (unfused) carpels. Each carpel forms a simple pistil. Examples include flowers like rose and strawberry. This often results in an aggregate fruit.
- Syncarpous: This condition occurs when a flower has multiple carpels that are fused together to form a single, compound pistil. This is very common in flowering plants like tomato, mustard, and hibiscus. This typically results in a single fruit developing from the fused ovary.
8. Why does a pea pod have a single chamber, while an orange has multiple segments?
This difference is a real-world example of carpel structure. A pea pod develops from a flower with a simple pistil, which consists of only one carpel (monocarpellary). This single carpel forms a single chamber (locule) for the seeds. In contrast, an orange develops from a flower with a compound pistil, where multiple carpels have fused together (syncarpous). Each segment or 'slice' of the orange corresponds to one of the original carpels, which is why the fruit is divided into multiple chambers.
