Consider the system:

\begin{align*} x'&=(1-x-y)x\\ y'&=(4-7x-3y)y \end{align*}

The system has a saddle point at (1/4,3/4). How can I plot the separatrices on the phase portrait having domain $\{(x,y):\ 0\le x\le 1,\ 0\le y\le 2\}$?