Realizing that as a Jew he would not be appointed full professor, he diverted his attentions to applied botanics, and founded several companies of tropical industrial plantations in Germany's colonies.

[citation needed] in 1931 he founded the National Botanic Garden of Israel in the Hebrew University in Jerusalem on Mount Scopus together with the botanist Alexander Eig.

[3] Taxa named include Dovyalis caffra, Virola peruviana, Cephalosphaera usambarensis, and the pitcher plant Nepenthes treubiana.

The extent to which Jews were being persecuted in Germany through the 1930s was a hotly debated issue, with many apologists downplaying the centrality of race in Nazi ideology.

Based on official German publications and reliable external reports, it details the many methods adopted by the Nazi party against the Jews.