Which leader, who unified Germany in the 1860s has a genus of plants in Madagascar named after him? 
Bismarckia:  The genus is named for the first chancellor of the German Empire Otto von Bismarck and the epithet for its only species, Bismarckia nobilis, comes from Latin for 'noble'. Otto von Bismarck:  In the 1860s, he engineered a series of wars that unified the German states, deliberately excluding Austria, into a powerful German Empire under Prussian leadership.
Otto von Bismarck