\begin{tikzpicture}
    [edge from parent fork down,
    every node/.style={rectangle,thick,draw},
    edge from parent/.style={black,->,thick,draw},
    sibling distance=2.5cm
    ]
    \begin{scope}
    \node {\emph{Hypergraph}}
        child {node {\emph{Graph}}
            child {node {\emph{Directed\\Graph}}
                child {node {\emph{Forest}}
                    child {node {\emph{Tree}}
                        child {node {DelegatedTree}}
                        child {node {OrderedKAryTree}}
                    }
                    child {node {DelegatedForest}}
                }
                child {node {DirectedSparseGraph}}
                child {node {DirectedSparseMultiGraph}
                    child {node {DirectedOrderedSparseMultiGraph}}
                }
            }
            child {node {\emph{KPartiteGraph}} }
            child {node {SparseGraph}}
            child {node {SortedSparseMultigraph}}
            child {node {SparseMultigraph}
                child {node {OrderedSparseMultigraph}}
            }
            child {node {\emph{UndirectedGraph}}
                child {node {UndirectedSparseGraph}}
                child {node {UndirectedSparseMultiGraph}
                    child {node {UndirectedOrderedSparseMultiGraph}}
                }
            }
        };
    \end{scope}
    \begin{scope}[xshift=5cm]
    \node {\emph{MultiGraph}};
    \end{scope}

\end{tikzpicture}