Tree Facts Tree Facts Trees of Nashville TN The Tree Advantage Tree Facts By definition, a tree is a wooded plant that is a large in size.  It is also considered a perennial plant. The general guidelines for defining a tree by size are a plant that is a minimum of 20 feet in height when fully mature and has branches that shoot from a major stem or trunk. Trees have long lives in comparison to other plants with a few varieties living up to thousands of years old.  Some tree species can grow as high as 328 feet. Trees play an important part in nature by helping to prevent erosion.  They offer a lot of visual appeal in landscapes as well.  The most universal construction substance is the wood that comes from trees. Trees have five basic parts.  They are the trunk, branches, roots, twigs and leaves. The stems of tree are made up of two different kinds of tissues.  One is a support tissue call xylem, the other is a transport tissue called phloem. There are two main groups of trees.  They are called endogenous and exogenous based on how the tree stem or trunk gets thicker. The larger of the two groups is the exogenous tree group.  This tree group includes all of the broadleaf and conifer trees.  Exogenous trees have stems that grow by adding new wood on the outside of the stem right underneath the bark. The endogenous tree group, which includes the palms, has stems that develop in size by inwardly growing new wood.  This tree group also generates growth rings. The growth rings of the endogenous trees can be seen more readily in temperate climates.  This is because of the various temperatures that occur during the yearly cycle of the tree which cause the tree to experience changes in its growth rate. Growth rings can be helpful in judging how old a tree is by the process of counting them.  They can also be useful in finding out the age of historical trees.  The science of studying and counting growth rings is called dendrochronology.