Roots

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 carries the water and nutrients needed for plants to grow.

Stems

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.

Leaves

Leaves are the food making factories of green plants. Leaves come in many different shapes and sizes. Leaves can be simple (one leaf attached to a stem). The part that joins the leaf of a plant to the main stem is called petiole. 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.
The main function of leaves is to make food for the plants. They also allow water vapor to escape through them (transpiration) and exchange gases with the atmosphere. Leaves contain veins that carry water, minerals, and food around the leaf Pine trees and most other conifers have narrow needles that are leaves. This shape enables them to survive cold places. They are also flexible to bend under heavy snow conditions. Cacti have very thin leaves (spines) that are often sharp and dangerous. This enables them to conserve water and allows the cactus to survive in very dry environments as well as to protect the plant.

Flowers

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, tubelike structure called the style. The style leads to the ovary that contains the female egg cells called ovules.

The male parts are called stamens and usually surround the pistil. The stamen is made up of two parts: the anther and filament. The anther produces pollen (male reproductive cells). The filament holds the anther up.
During the process of fertilization, pollen lands on the stigma, a tube grows down the style and enters the ovary. Male reproductive cells travel down the tube and join with the ovule, fertilizing it. The fertilized ovule becomes the seed, and the ovary becomes the fruit.

Petals are also important parts of the flower, because they help attract pollinators such as bees, butterflies and bats. You can also see tiny green leaf-like parts called sepals at the base of the flower. They help to protect the developing bud.
Some plants don't produce seeds. They produce spores. Ferns are among these.

Fruit and seeds

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.
Every seed is a tiny plant (embryo) with leaves, stems, and root parts waiting for the right things to happen to make it germinate and grow. Seeds are protected by a coat. This coat can be thin or thick and hard. Thin coats don't protect the embryo well. But thick coats can let the embryo survive some tough conditions.
The seed also contains a short-term food supply called the endosperm which is formed at fertilization but is not part of the embryo. It is used by the embryo to help its growth.
Plants with one cotyledon (like corn) are called monocots. If they have two cotyledons (like beans), they are called dicots.
Seeds are a plant's way of getting from one area to another by either wind, water or animals.