When you are done with this page, try the Stems Quiz.
The stem is a part of the plant that holds up other structures such as the leaves and flowers. This is important as the leaves need to be held up to the sun to get its light for photosynthesis and the flowers need to be held up to be available for pollination. Stems also carry water and minerals up from the roots to the leaves to help with photosynthesis and take food back down to be stored and distributed to the plant as it has need. The tubes in the stem that take the water and minerals up into the plant are the xylem and the tubes that carry the food back down are called the phloem.
Stems can be of several sorts, herbaceous and woody. The herbaceous stems are green and fairly bendable. The woody stems as their name implies, are covered by bark. The herbaceous stem has more pith for its size. The cambium which causes woody stems to get bigger in width is not as active in the herbaceous stems. Most herbaceous plants are annuals or planted yearly. The herbaceous stem has little notches where leaves develop. Woody stems have scars where twigs and fruit have dropped off and little openings for transpiration.
There are different sorts of aerial stems or stems that are upright. They include tendrils, runners and thorns. Succulents are plants with bigger fleshy stems that help plants retain water in dry areas. Some stems are underground such as bulbs and tubers. There are also stems that cannot hold themselves up, but need to be supported.
Stems are valuable to man as a source of food and its wood is used for many products. The sap from many stems is used for resins and latexes.