In this lesson, we’ll look at the parts of a flower and learn their functions.
These natural beauties provide indispensable services to the plants they adorn.
Quick Review of Flower Types
Flowers serve several purposes in our lives. You may think of giving flowers to friends or loved ones to show them that you care or that you are sorry. However, flowers serve many vital roles for plants.
Let’s look at the roles that flowers play as well as their male and female components.As we look at the parts of a basic flower, we will look back at this diagram. Before getting into the parts of the flower, we first need to review which types of plants have flowers. You may remember that plants are divided into several groups. The first division was vascular and nonvascular.
Nonvascular plants do not have flowers. Vascular plants were divided into gymnosperms and angiosperms. Gymnosperms also do not have flowers. That means that only angiosperms have flowers. Both divisions of angiosperms – the monocots and the dicots – have the same basic structures in their flowers.
Complete vs. Incomplete Flowers
Flowers can be described as either complete or incomplete.
Complete flowers are those that have all four whorls of parts, while incomplete flowers are those that lack one or more of the whorls. These definitions may leave you asking ‘What are whorls?’ In flowers, there are different layers of parts that are described as whorls. There are four possible whorls, including the calyx, corolla, androecium, and gynoecium. Let’s look at each part more closely.
The main structure in the androecium is called the stamen and is the male structures in the flower. The stamen is made of two parts: the filaments and the anthers.
The filaments are the slender stalks of the stamen seen here. The anther is the top of the stamen and contains pollen. We can see the anther here on top of the filament. When you look at a flower, the anthers often appear a yellowish color because they contain pollen. This pollen is often what causes allergies or can just make you sneeze if you sniff a flower too closely. Let’s label the androecium on our diagram. We can see the stamen with the filament and anther within this whorl of the flower.
The innermost whorl contains the female parts and is called the gynoecium. Again, let’s look at the root words. The Greek word ‘gyne’ means ‘woman,’ and we already know that ‘oikos’ means ‘house.
‘ So, the word ‘gynoecium’ means ‘woman house.’ There are several female parts in the flower, so let’s look at these more closely.The female part that is easiest to see in the flower is the carpel.
The carpel contains the ovules, ovary, style, and stigma. Flowers often contain either one or two carpels. The outer parts of the carpel that you may see are the style and the stigma. The stigma is the top, pollen-receiving structure. It is sticky so that the pollen will stay on the stigma and can then fertilize the plant. If there are two carpels, then there are two stigmas.
Below the stigma is the style, which is the narrow part between the stigma and the ovary. We can see this in the picture here. The stigma is the top flat part, and this narrow tube is the style. The part directly below the style is the ovary. This swollen part at the bottom of the carpel produces ovules.
We can also see this in our diagram here. Ovules, which are produced in the ovary, develop into seeds. As you can see, the gynoecium has a few more parts than the androecium.
All parts of the flower serve a distinctive purpose.
The outermost layer is the calyx, which has sepals that protect the flower when it is still a bud. The main part of the flower that you recognize is the corolla, which is made up of the petals. This generally colorful part of the flower helps to attract pollinators.Next we looked at the male structures of the plant, which were found in the androecium. In here we found the stamen, which is made up of filaments and anthers. The anthers produce pollen and are located at the top of the stamen.
The last whorl we looked at was the gynoecium, which contains the female parts. Flowers may have one or two carpels, which contain:
- the stigma – the top sticky part that catches pollen
- the style – the narrow tube supporting the stigma
- the ovary – the swollen part at the bottom that produces ovules that develop into seeds
Remember that when a flower contains all four whorls it is considered to be complete. However, if one or more whorls are missing, the flower is incomplete.
After watching this lesson, you should be able to:
- Identify the different parts of flowers and their functions (male and female)
- Determine whether a flower is complete or incomplete