In 1884-85 he conducted botanical research in Egypt on behalf of the Königlich-Preußischen Akademie der Wissenschaften. In 1887 he obtained his habilitation, followed by work as an assistant to Adolf Engler (1844-1930) at the Botanical Museum in Berlin. Later he journeyed to East Africa, where he performed phytogeographical studies at Mount Kilimanjaro, as well as conducting investigations on the regions' resources from an economic standpoint. On the expedition he collected numerous plant species new to science.