diff --git a/lib/matplotlib/streamplot.py b/lib/matplotlib/streamplot.py
index 6de221476490..d6bceb6c9915 100644
--- a/lib/matplotlib/streamplot.py
+++ b/lib/matplotlib/streamplot.py
@@ -26,7 +26,9 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
     Parameters
     ----------
     x, y : 1D/2D arrays
-        Evenly spaced strictly increasing arrays to make a grid.
+        Evenly spaced strictly increasing arrays to make a grid.  If 2D, all
+        rows of *x* must be equal and all columns of *y* must be equal; i.e.,
+        they must be as if generated by ``np.meshgrid(x_1d, y_1d)``.
     u, v : 2D arrays
         *x* and *y*-velocities. The number of rows and columns must match
         the length of *y* and *x*, respectively.