 From 1918 he worked closely with the Forest Research Institute at Buitenzorg (now Bogor), Java.In 1925, Endert accompanied a plant collecting expedition to central Borneo (Midden-Oost-Borneo-Expeditie), during which he collected "Nepenthes fusca" and "Nepenthes mollis" for the first time.In 1938 he was stationed at Makassar in southwestern Sulawesi, tasked with the supervision of the forests.