\usepackage {pstcol,pst-node,pst-tree} \psset{arrows=->,framearc=.2} \newcommand{\Treebox}[1]{% \Tr{\psframebox{#1}}} \pstree[treemode=R] {\Treebox{A$\rightarrow$B}}{ \pstree{ \Treebox{B$\rightarrow$C} }{ \Treebox{A$\rightarrow$D} \pstree[treemode=L] {\Treebox{B$\rightarrow$E}} {\Tn\TC[arrows=<-]} } }