Tree

The word tree has its origins in Proto-Indo-European (PIE) drew-o (tree), from the PIE root deru (to be firm, solid, steadfast). PIE deru is also the source of the words true and truth.
 
From these PIE beginnings come Proto-Germanic trewam (the source of Old Frisian tre, Old Saxon trio, Old Norse tre) and Old English treo, treow (tree, particularly the oak tree; also, timber, wood, beam, log, stake).
 
Old English treo is the root of Old English treowwyrhta (tree-wright), a word replaced during the evolution of English for some reason by Latin carpentarius (cartwright) rather than by what would seem to be the more logical Latin word--lignarius (carpenter; i.e., lignum is Latin for wood).
 
The Old English words triewe (faithful, trustworthy, honest, steadfast) and triewo (faith, faithfulness, fidelity, loyalty, veracity), also from PIE deru and from Proto-Germanic treuwaz (having or characterized by good faith), are the origins of the words true and truth.
 
Given these common origins of tree and truth, consider the tree as a metaphor for truth. A tree, firmly rooted in the soil, begins as a seed or sapling and over time continues to grow and branch out. A tree, nourished by the soil and air and light in which it grows, nourishes and sustains the other trees around it, and when it dies it returns to the soil.
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
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