Although many of the modified stems do not look or grow like the typical stems described above, their tissues and the patterns of their development are like those of other stems. In most cases, plants with modified stems also have conventional stems.

Rhizomes, or rootstocks, are roughly cylindrical stems that grow horizontally underground. They store food and live throughout the year. Under favorable conditions, as in spring, they send up new shoots. Many weeds, such as bind-weed, quack grass, and horse nettle, have rhizomes, thus making them particularly difficult to eradicate. Other plants with rhizomes are iris, asparagus, rhubarb, and most ferns. The chief functions of rhizomes are reproduction and food storage.

Tubers, such as the white potato, are greatly enlarged, short underground stems filled with stored food in the form of starch. The eyes of a potato are actually buds from which conventional, aerial stems and leaves will grow. Potato fields are planted by placing pieces of tuber with one or two eyes into the ground.

Bulbs consist of a small stem surrounded by numerous fleshy leaves. Among the plants with bulbs are onions, daffodils, and tulips. Bulbs store food in the fleshy leaves, usually in the form of sugar. They are also reproductive structures.

Corms superficially resemble bulbs, but, unlike bulbs, they consist mostly of stem tissue bearing a few small, scaly leaves. Like bulbs, corms store food, but in their stem tissue rather than in the leaves. Corms are also reproductive structures.

In various climbing plants, such as the grape and the Boston ivy, some parts of stems are modified into climbing organs called tendrils. In some plants, such as the morning glory and sweet potato, the stems grow spirally around a support. Such stems are called twiners.

Stems that grow in a creeping fashion horizontally above the surface of the soil are called runners, or stolons. If the nodes of these stems touch the soil, new plants develop. The most familiar plant with stolons is the strawberry. In some plants, such as honey locust and osage orange trees, portions of stems are modified into thorns. Some cacti and a few other kinds of plants have stems that closely resemble leaves in appearance; that is, they are leaflike in shape and are green and thus manufacture food.