Many varieties of bean plants are available to the home gardener, but all of them have similar plant parts. Understanding how each part works not only helps you identify the plant, it also helps you understand how to grow a successful bean crop. Beans grow quickly, which also makes them suitable for teaching children about the parts of a plant.
Beans have a fibrous root system. The roots of beans and other legumes produce their own nitrogen in the soil when exposed to nitrogen-fixing bacteria. Nitrogen is the primary nutrient needed for bean plant growth, so the roots' ability to do this helps ensure the health of the plant as it matures.
The stem supports the leaves, flowers and later the pods. The stem of the bush bean grows straight, with small side branches along its length. Pole and other vine bean varieties don't just produce side branches; they also form small twining tendrils that wrap around trellises and other supports to help the stem climb.
Beans produce broad leaves that are wide along the base and pointed at the tip. These large leaves collect nutrients from the sun while also shading the developing pods so they aren't damaged.
Some bean flowers are ornamental, such as the crimson blooms of the scarlet runner bean. Blossom colors also include white, pink and yellow, depending on the specific bean variety. Bean flowers self-pollinate, so only one plant is necessary to grow bean pods.
Pods vary in size and color, ranging from green to red and nearly black. Depending on the variety, the pods may hold anywhere from two to five bean seeds–and sometimes more. Pods grow from successfully pollinated flowers. Some beans are grown for their edible pods, such as green beans, which are harvested when the pod is still green and tender. Others are grown for the mature bean inside, such as kidney beans, which are harvested after both the bean and pod have dried on the plant.