The stem of houseplants is called its skeleton. It is considered the most important part of the crop, although in some it may be deformed or underground. All plants have a stem. Crops vary in its structure. It is this part that carries the important organs of life. Flower buds, growth points, and leaves are formed on it. Also, the stem has buds and as a product of flowering, fruits.

The most important function of the skeletal stem is the movement of water and juices with mineral and organic elements through it. Moisture is absorbed through the root and moves up the plant. Water and nutrients can be stored in the stem. This strategic reserve is characteristic of succulents (e.g., noctocacti). The process of leaf photosynthesis also produces nutrients that travel up the stem to the roots and other organs.

Several groups are known in the scientific literature into which stems are divided according to their characteristics:

• Herbaceous – succulent, soft with a delicate watery texture. Found in herbs of annuals and perennials;
• Woody stems – hard, covered with bark or crust, often dry. Characteristic of shrubs and trees (trunk);
• Upright – characteristically upright, growing vertically, relative to the ground;
• Flowing – loping growth, more often the stems cover the ground or hang down from hanging pots;
• Climbing – twined around supports and other structures;
• Clinging – such stems in creeper and sweet pea;
• Underdeveloped or underground – are characteristic of plants whose leaves are gathered in a root rosette, as in the senpolias. More often they are under the ground or at the same level with it.