Of the numerous tributaries which join the Rhine within the province, the most important are the Nahe, the Mosel and the Ahr on the left bank, and the Sieg, the Wupper, the Ruhr and the Lippe on the right.
The Scotch fir; birches are also Lippe abundant.
Another instance of the emperors interference, constitutionally of more importance as directly affecting the rights of the German sovereigns, was in the question of the succession to the principality of Lippe (see LIPPE).
The basin of the Lippe and the upper basin of the Ems were inhabited by the Bructeri, and in the same neighborhood were the Ampsivarii, who derive their name from the latter river.
By the line of hills called the Haar or Haarstrang, which divides the basins of the Lippe and Ruhr.