The parts of a tree

Tree roots anchor the structure and provide water and nutrients.

The parts of a tree are the roots, trunk(s), branches, twigs and leaves.

Tree stems consist mainly of support and transport tissues (xylem and phloem). Wood consists of xylem cells, and bark is made of phloem and other tissues external to the vascular cambium.

Trees may be grouped into exogenous and endogenous trees according to the way in which their stem diameter increases. Exogenous trees, which comprise the great majority of trees (all conifers, and almost all broadleaf trees), grow by the addition of new wood outwards, immediately under the bark.
Endogenous trees, mainly in the monocotyledons (e.g., palms and dragon trees), but also cacti, grow by addition of new material inwards.

The roots of a tree are generally embedded in earth, providing anchorage for the above-ground biomass and absorbing water and nutrients from the soil.
It should be noted, however, that while ground nutrients are essential to a tree's growth the majority of its biomass comes from carbon dioxide absorbed from the atmosphere (see photosynthesis). Above ground, the trunk gives height to the leaf-bearing branches, aiding in competition with other plant species for sunlight. In many trees, the arrangement of the branches optimizes exposure of the leaves to sunlight.