A stem develops from a bud and consists of leaves. Stems swell at the nodal points where the leaf is attached. The area between the nodes is called an internode. The stem functions to give support and display leaves, fruits and flowers, carries water and mineral nutrients from roots to the leaves, carries food produced by the green parts of the plant to its roots. In the plants like cacti, which do not have leaves, the entire food is produced in the green stem. Stems are annual, biennial, or perennial though some plants having perennial roots possess annual stems.
Some stems store food material known as tubers, corm, rhizomes, and bulbs. Stems are also modified as tendrils, runners, and thorns in certain plants. For example, tendrils in Vitis sps., and Parthenocissus quinquefolia are modified stems.
Crowns are a type of stems that are very small and not very inconspicuous. The pants with such stems are called as acaulescent. For example, Gerbera spp. The stem base from where roots arise is called as a crown.
Simple stems are those without branches as seen in Carica papaya and Zea mays. Branched stems have more than one terminal bud and have branches.
Climbing stems are weak and they depend on the other plants and posts for support as in Bougainvillea and Pyrostegia venusta.
Creeping stems spread on the ground surface and send roots into the ground from the joints and nodes. Examples, Wedelia trilobata and Lantana montevidensis.
Rhizomes are a type of stems that are prostrate, thick, and subterranean. They have leaves arising from one side and roots from another side. For example, Canna X generalis, Begonia heracleifolia.
Stolons are one type of stems that are slender, modified and grow on the surface of the ground with roots at the nodes. For example, Fragaria X Ananassa and Stenotaphrum secundatum.
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