Why do plants make fruit?
When this bird eats a berry, it also consumes the seeds contained inside. The bird may fly for many miles before digestion is complete and the seeds are excreted. This allows the plant to spread its seeds to a new location. For this reason, plants that make fruits have been very successful.
Angiosperms, in the phylum Anthophyta, are the most successful phylum of plants. This category also contains the largest number of individual plants (Figure below). Angiosperms evolved the structure of the flower, so they are also called the flowering plants. Angiosperms live in a variety of different environments. A water lily, an oak tree, and a barrel cactus, although different, are all angiosperms.
The Parts of a Flower
Even though flowers may look very different from each other, they do have some structures in common. The structures are explained in the picture below (Figure below).
- The green outside of a flower that often looks like a leaf is called the sepal (Figure below). All of the sepals together are called the calyx, which is usually green and protects the flower before it opens.
- All of the petals (Figure below) together are called the corolla. They are bright and colorful to attract a particular pollinator, an animal that carries pollen from one flower to another. Examples of pollinators include birds and insects.
- The next structure is the stamen, consisting of the stalk-like filament that holds up the anther, or pollen sac. The pollen, which is found at the top of the stamen, is the male gametophyte.
- At the very center is the carpel, which is divided into three different parts: (1) the sticky stigma, where the pollen lands, (2) the tube of the style, and (3) the large, bottom part, known as the ovary.
The ovary holds the ovules, the female gametophytes. When the ovules are fertilized, the ovule becomes the seed and the ovary becomes the fruit.
The following table summarizes the parts of the flower (Table below).
|sepals||The green outside of the flower.|
|calyx||All of the sepals together, or the outside of the flower.|
|corolla||The petals of a flower collectively.|
|stamens||The part of the flower that produces pollen.|
|filament||Stalk that holds up the anther.|
|anther||The structure that contains pollen in a flower.|
|carpel||“Female” part of the flower; includes the stigma, style, and ovary.|
|stigma||The part of the carpel where the pollen must land for fertilization to occur.|
|style||Tube that makes up part of the carpel.|
|ovary||Large bottom part of the carpel where the ovules are contained.|
|ovules||Part of the ovary that is the female gametophyte and that after fertilization becomes the seed.|
How Do Angiosperms Reproduce?
Flowering plants can reproduce two different ways:
- Self-pollination: Pollen falls on the stigma of the same flower. This way, a seed will be produced that can turn into a genetically identical plant.
- Cross-fertilization: Pollen from one flower travels to a stigma of a flower on another plant. Pollen travels from flower to flower by wind or by animals. Flowers that are pollinated by animals such as birds, butterflies, or bees are often colorful and provide nectar, a sugary reward, for their animal pollinators.
Why Are Angiosperms Important to Humans?
Angiosperms are important to humans in many ways, but the most significant role of angiosperms is as food. Wheat, rye, corn, and other grains are all harvested from flowering plants. Starchy foods, such as potatoes, and legumes, such as beans, are also angiosperms. And, as mentioned previously, fruits are a product of angiosperms that increase seed dispersal and are nutritious.
There are also many non-food uses of angiosperms that are important to society. For example, cotton and other plants are used to make cloth, and hardwood trees are used for lumber.
- Angiosperms are plants that produce flowers and fruit.
- Angiosperms can be self-pollinated, meaning pollen falls on the stigma of the same flower, or cross-fertilized, during which pollen from one flower travels to a stigma of a flower on another plant.
Use the resource below to answer the questions that follow.
- Angiosperms: The Secrets of Flowers at http://www.youtube.com/watch?v=sr4Khc7BUzA (5:46)
- How many species of angiosperms exist today?
- How many species of gymnosperm exist today?
- When did angiosperms become the most abundant type of plant on the planet?
- When do angiosperms grow fruit?
- Where are the sex organs of angiosperms located?
- What part of the plant becomes the fruit?
- What is the difference between a superior and inferior ovary?
- How are angiosperms like gymnosperms? How are they different?
- What makes up the female part of the flower?
- What part of the flower is the male gametophyte?
- What is self-pollination?
- How does pollen travel to another plant?