Dutch mycologist (1893-1927).
Casper van Overeem (1 October 1893 – 28 February 1927) was a Dutch mycologist who pioneered the systematic study of tropical fungi in the Dutch East Indies (present‑day Indonesia). Initially trained as a teacher, he developed his scientific expertise under the botanist Hugo de Vries before earning his doctorate from the University of Zurich in 1920 with research on chromosome variations in Oenothera. At Buitenzorg (now Bogor), he established a mycology department at the botanical gardens' herbarium and authored the illustrated series Icones Fungorum Malayensium alongside numerous scientific pu