\documentclass[12pt]{article}

\usepackage{cm-lingmacros, trees, tree-test}

\begin{document}

This document uses trees written to independent files by the
{\tt trees} preprocessor.  Here's the first one, one with {\tt .>}:
\begin{example}
\input trees/firsttree.tex
\end{example}
And here's the second, done likewise:
\begin{example}
\input trees/secondtree.tex
\end{example}
And here are two trees done with {\tt .>>}:
\begin{examples}
\input trees/twotrees.tex
\end{examples}
\end{document}