The concept of a tree of life is a widespread mytheme or archetype in the world's mythologies, related to the concept of sacred tree more generally, and hence in religious and philosophical tradition.
The expression Tree of Life was used as a metaphor for the phylogenetic tree of common descent in the evolutionary sense in a famous passage by Charles Darwin (1872).
The tree of knowledge, connecting to heaven and the underworld, and the tree of life, connecting all forms of creation, are both forms of the world tree or cosmic tree, according to the Encyclopædia Britannica, and are portrayed in various religions and philosophies as the same tree.
Various trees of life are recounted in folklore, culture and fiction, often relating to immortality or fertility. They had their origin in religious symbolism.
(source : Wikipedia)