Though they were later implemented by Willi Hennig in his fundamental work on phylogenetic systematics, Zimmermann's contributions to this field have largely been overlooked.
[3][4] Throughout his lifetime he received numerous awards such as Honorary member of the Zoological-Botanical Society in Vienna, Honorary Member of the Association of German Biologists, and the Serge von Bubnoff Medal of the Geological Society of the GDR (1961), the Federal Service Cross, First Class (1962), and the Merit Medal of the State of Baden-Württemberg (1978).
[9] Though he recognized the importance of subjective human abstractions in categorizing organisms, he strayed as far from that view as possible when identifying key phylogenetic characters based on phenetic differences.
He considered biased the idealistic method, which focuses on a form chosen intuitively based on human idealism and does not need to actually exist in nature.
Wolf-Ernst Reif (1986) in his review on macroevolution concludes that Zimmermann was successful at deducing this synthetic view of evolution prior to the completion of the formulation of Modern Synthesis.
[12][13][14][15] Tracing character state changes of single traits helped elucidate the evolutionary relationships between organisms, such as in identifying the parallel transition of isogamy to anisogamy.
Zimmermann contributed insight into the evolution of the stele (central part of the root system of plants) by considering phylogenetic similarities and attempting to deduce its ancestral morphology.