Phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. A major task of phylogenists is to determine the ancestor-descendant relationships among known species (both living and extinct).
Philology is the study of ancient texts and languages. Historical linguistics (or comparative linguistics) is the branch of philology that studies languages and their interrelationships. A philological tree (or tree of languages) traces the evolutionary interrelationships among languages believed to have originated from a common ancestor.
This issue of our blog compares the tree of life to the tree of languages.