In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. Trees usually reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms, bananas, and bamboos also produce seeds, but tree ferns produce spores instead. Trees play a significant role in reducing erosion and moderating the climate. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses.