Newick is a simple text-based format for describing a tree with edge lengths using parentheses and commas.

The GraphTheory[Newick] command can convert a Graph representing a tree to its Newick encoding as a string, and vice versa.

The GraphTheory[ImportGraph] and GraphTheory[ExportGraph] commands can read from and write to this format.

The general-purpose commands Import and Export also support this format.

$T≔\mathrm{GraphTheory}:-\mathrm{Graph}\left(\left\{\left\{1\,11\right\}\,\left\{1\,12\right\}\,\left\{2\,10\right\}\,\left\{2\,12\right\}\,\left\{3\,10\right\}\,\left\{4\,5\right\}\,\left\{4\,9\right\}\,\left\{4\,11\right\}\,\left\{5\,7\right\}\,\left\{6\,12\right\}\,\left\{8\,11\right\}\right\}\right)$

$T≔\mathrm{Graph\; 1:\; an\; undirected\; graph\; with\; 12\; vertices\; and\; 11\; edges}$

$\mathrm{GraphTheory}:-\mathrm{Newick}\left(T\right)$

$''((((7)5,9)4,8)11,(((3)10)2,6)12)1;''$

$\mathrm{Export}\left(''mytree.newick''\,\mathrm{DG}\,\mathrm{base}=\mathrm{homedir}\right)$

$35$

"Newick file format", Wikipedia, https://en.wikipedia.org/wiki/Newick_format.