Trees are not a monophyletic taxonomic group but consist of a wide variety of plant species that have independently evolved a trunk and branches as a way to tower above other plants to compete for sunlight. The majority of tree species are angiosperms or hardwoods; of the rest, many are gymnosperms or softwoods.
A tree is a woody plant that regularly renews its growth. Most plants classified as trees have a single self-supporting trunk containing woody tissues, and in most species the trunk produces secondary limbs, called branches.
Find detailed information about nearly 200 different tree species. Learn the different layers of a tree and why each is important. Get a breakdown of how trees are classified and explore the definitions of various tree-related terms.
The crown of the tree is made up of the leaves and branches. The trunk of the tree supports the crown and serves as a highway for food made in the leaves to travel to the roots and for water and nutrients from the roots to travel to the leaves.
In general, a plant is considered a tree if its height reaches more than 13 feet, lives for many years, and has a woody stem. Moreover, there are certain features which are common in trees.
The earliest trees were tree ferns, horsetails and lycophytes, which grew in forests in the Carboniferous period; tree ferns still survive, but the only surviving horsetails and lycophytes are not of tree form.