Many thanks Piers and Koichi,
I also found this page in Japanese that shows some variations of that Mon: http://www.otomiya.com/kamon/kika/matsukawa.htm
Its translation via Babelfish results in the following:
"Matsukawa water caltrop - It waits, or is lonesome.
With the design which furthermore attaches the small water caltrop to the top and bottom in the water caltrop, it is derived from the form having been similar to the crust of the pine. It is made the Japanese peculiar pattern."
What I ask myself is: Could the design also resemble a water caltrop ( http://images.google.de/images?q=water+ ... art=0&sa=N ) ?
"Caltrop" also refers to a small iron weapon used in medieval times, with four points, designed to pierce the hooves of enemy cavalry horses.
Maybe I just followed a stupid idea here, that was caused by some weak (automatic) translation...
best,