In January 1971 Dr. Simon Jan van Ooststroom, senior botanist of the Rijksherbarium, retired on reaching the age of 65, having been on the staff since November 1934. Though this event will to a certain extent change, but not interrupt, his work, it is nevertheless worth commemorating, as he has so many contacts at home and abroad, all of whom have profited from his wide knowledge which he shared freely. He was born in Rotterdam in 1906, where he received his primary and part of his secondary education. He completed the latter in Schiedam and entered the University of Utrecht in 1924. He became the assistant of Prof. Dr. A. Pulle in January 1927. By chance he became interested in the genus Evolvulus and this led him to compose an excellent world monograph of this genus for which he was awarded his doctor’s degree in 1934 and which furthermore caused a life-long interest in the bindweed family, on which he became a most reliable authority, especially for the Indo-Australian region. Many papers emanated from these studies, culminating in his treatment (assisted by Dr. R. D. Hoogland) of the family in Flora Malesiana (1953).