\begin{tikzpicture}[xscale=0.4,yscale=0.2]

\draw[dotted] (0,0) -- (0,14) node[right] {saddle pos};

\draw[red] plot[mark=+,mark options={scale=0.7}] file{valueplot-flowlines_1.dat};
\draw[green] plot[mark=x,mark options={scale=0.7}] file{valueplot-flowlines_2.dat};
\draw[blue] plot[mark=asterisk,mark options={scale=0.7}] file{valueplot-flowlines_3.dat};
\draw[magenta] plot[mark=square,mark options={scale=0.7}] file{valueplot-flowlines_4.dat};

\end{tikzpicture}