PERL is a rich and expressive scripting language that appeals a lot to people who want to get things done quickly.

For starters one may take a look at this one first http://search.cpan.org/~rkinyon/Tree-1.01/lib/Tree.pm

Some of the tree implementations available are

Tree                A tree datastructure    
Tree::AVL           AVL tree for efficient storage and retrieval    
Tree::DAG_Node      base class for trees    
Tree::Fat           Embeddable F-Tree algorithm suite   
Tree::List2Tree     Convert list of nodes into tree structure   
Tree::Menu          Menus as trees  
Tree::Nary          Perl implementation of N-ary search trees   
Tree::Node          Memory-efficient tree node implementation  
Tree::Predicate     predicate trees, usually for SQL    
Tree::Suffix        Interface to the libstree library   
Tree::Ternary       Perl implementation of ternary search trees     
Tree::Ternary_XS    XS implementation of ternary search trees   
Tree::Trie          An implementation of the Trie data structure

For the complete list with links to code and modules, check out
http://search.cpan.org/modlist/Data_and_Data_Types/Tree