Roots are the part of the plant that is typically underground. Their role is to anchor the plant in place and transfer water and nutrients from the ground to the plant. Plants generally have either a taproot system, made up of a large, central root (like a carrot) or a fibrous root system, made up of many thin, stringy roots (like turf grass).
The stem transports the water and nutrients absorbed by the root system to the leaves. The leaves produce food, which is then taken to other parts of the plant by two kinds of cells: xylem cells move the water, and phloem cells move the food. Stems also support the upper part of the plant, enabling the leaves to access the sunlight and make food.
The job of the leaves is to make food for the plant through a process called photosynthesis. Leaves change the energy they get from the sun, carbon dioxide from the air and water from the soil into glucose, a sugar that the plant uses for food.
Flowers are the reproductive part of a plant. They have a female part, called the pistil, and male parts, called stamens, which produce pollen. For a plant to reproduce, the pollen must go from the stamen to the top of the pistil, which is called the stigma. This process is called pollination, and there are two kinds: self-pollination and cross-pollination. Self-pollination is when pollen goes from the stamen to the pistil of the same plant; cross-pollination is when pollen is moved from one plant's stamen to a different plant's stigma. Cross-pollination only works if the plants are in the same species; pollen from a tulip can't pollinate a pear tree. Pollinators, like bees, move the pollen between plants; so do elements like the wind. Once a plant has been pollinated, the seeds and fruit can begin to grow.
The fruit is the ripened ovary of a plant that contains the seeds. Each seed is a tiny plant embryo with its own leaf, stem and root parts. When animals eat the fruit, they excrete the seeds somewhere else, allowing the plant to grow in a new location. Weather elements, such as wind and rain, also help spread the seeds.