EXTERNAL AND INTERNAL FEATURES OF FLOWERING PLANTS.
Flowering plants are angiosperms and they include monocotyledonous and dicotyledonous plants. Some flowering plants reproduce sexually by use of flowers as the reproductive organs. The flowers bear the gametes that fuse to form a zygote. The zygote develops into an embryo which grows and develops into a new plant. You should have noted, some flowering plants can also reproduce by vegetative propagation (asexually) using their vegetative parts. For example, the sweet potato plant flowers but it is grown using the vegetative parts.
Basic parts of most flowering plants are roots, stems, leaves, flowers, fruits, and seeds.
The roots help provide support by anchoring the plant and absorbing water and nutrients needed for growth. They can also store sugars and carbohydrates that the plant uses to carry out other functions. Plants can have either a taproot system (such as carrots) or a fibrous root system (such as turf grass). In both cases, the roots are what carry the water and nutrients needed for plants to grow.
Stems carry water and nutrients taken up by the roots to the leaves. Then the food produced by the leaves moves to other parts of the plant. The cells that do this work are called the xylem cells. They move water. The phloem cells move the food. Stems also provide support for the plant allowing the leaves to reach the sunlight that they need to produce food. Where the leaves join the stem is called the node. The space between the leaves and the stem is called the internode. You’ll find out why this is so important as the mystery develops.
Leaves are the food making factories of green plants. Leaves come in many different shapes and sizes. Leaves can be simple. They are made of a single leaf blade connected by a petiole to the stem. An oak leaf or a maple leaf is examples. A compound leaf is a leaf made up of separate leaflets attached by a petiole to the stem like an ash or a locust. Leaves are made to catch light and have openings to allow water and air to come and go. The outer surface of the leaf has a waxy coating called a cuticle which protects the leaf. Veins carry water and nutrients within the leaf.
Leaves are the site of the food making process called photosynthesis. In this process, carbon dioxide and water in the presence of chlorophyll (the green pigment) and light energy are changed into glucose (a sugar). This energy rich sugar is the source of food used by most plants.
Photosynthesis is unique to green plants! Photosynthesis supplies food for the plant and oxygen for other forms of life.
A green plant helped make the oxygen you are breathing today
Flowers not only look pretty but, in fact, are important in making seeds. Flowers have some basic parts. The female part is the pistil. The pistil usually is located in the center of the flower and is made up of three parts: the stigma, style, and ovary. The stigma is the sticky knob at the top of the pistil. It is attached to the long, tube-like structure called the style. The style leads to the ovary that contains the female egg cells called ovules.
The fruit is the ripened ovary of a plant containing the seeds. After fertilization, the ovary swells and becomes either fleshy or hard and dry to protect the developing seeds. Many fruits help seeds spread (maple seeds). Many things we call vegetables are really fruits such as tomatoes, cucumbers, and beans.
If you break into a seed, you will find that most of it contains a starchy substance called endosperm, which nourishes the embryo as it develops. The embryo includes one or two primitive leaves called cotyledons that also sometimes play a role in energy storage.
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