\documentclass[12pt]{article}

\usepackage{cm-lingmacros, lingtrees}

\begin{document}
Here is a very simple example:
\begin{example}
%%% begin tree
\tree{\ntnode{Z0}{S}{},
{\ntnode{Z1}{NP}{\nodeconnect{Z0}{Z1}},
{\tnode{Z2}{John}{\nodeconnect{Z1}{Z2}}}},
{\ntnode{Z3}{VP}{\nodeconnect{Z0}{Z3}},
{\ntnode{Z4}{V}{\nodeconnect{Z3}{Z4}},
{\tnode{Z5}{bit}{\nodeconnect{Z4}{Z5}}}},
{\ntnode{Z6}{NP}{\nodetriangle{Z3}{Z6}%
},
{\tnode{Z7}{Fido's best mate}{\nodetriangle{Z6}{Z7}%
}}}}}%%
%%end tree
\end{example}
That was easy, wasn't it?
\end{document}