With apologies to Joyce Kilmer

I think that I shall never see
A structure lovely as a tree.

A tree of nodes and pointers made
Less than linked lists, the time cost paid;

Recurse on down, have faith and leap
From node to node, out on the heap;

With smalls to left and bigs to right,
Algorithms are big-Oh height;

AVL or 2-3 are wise,
Height is order log the size.

With root aloft and leaves aground.
God's trees thus are upside-down.