Trees

Trees are perennial woody plants characterized by a single main stem, the trunk, that supports a branching crown and leaves. They typically reach greater height and live longer than most other plants, aided by secondary growth that thickens their stems via vascular cambium. Most trees reproduce by seeds produced in flowers or cones, and some form of flowers that attract pollinators.

Anatomy: The main structural tissues are xylem and phloem. Xylem conducts water and minerals from roots to leaves, while phloem distributes sugars produced by photosynthesis. The trunk is reinforced by lignified cells, and growth rings reveal age and past growing conditions. Roots anchor the plant and absorb water and nutrients, often extending beyond the canopy.

Ecology and importance: Trees perform photosynthesis, removing carbon dioxide from the atmosphere and storing carbon in wood and soils. They provide habitats and food for countless organisms, influence microclimates, prevent soil erosion, and contribute to nutrient cycling. Humans use trees for timber, fruit, shade, fuel, medicines, and cultural value.

Types and distribution: Trees are found in most biomes. They are broadly categorized into angiosperms (flowering trees) and gymnosperms (cone-bearing conifers). Common examples include oaks, maples, pines, and spruces. Growth forms include deciduous and evergreen, broadleaf and coniferous.

Threats and management: Forests face deforestation, fragmentation, pests, and climate change. Sustainable forestry, conservation, reforestation, and restoration efforts aim to preserve biodiversity while providing ecosystem services and resources.