The first substantial contribution of the Rijksherbarium towards the plant geography of Malesia and the Pacific was made by the German born J. G. Hallier in his paper ‘Über frühere Landbrücken, Pflanzen- und Völkerwanderungen zwischen Australien und Amerika’. In this paper he suggested that recent land connections had existed in the tropical Pacific from Japan over Hawaii to California and south to Peru and another connection in the south Pacific. His arguments besides botanical were also ethnographical and linguistic. H.J. Lam was not only responsible for the promotion of taxonomic research. He added chapters on phytogeography to his revisions of the Sapotaceae and Burseraceae. His papers on the subject always had a philosophical quality. He once compared phylogeny with a stream of potentialities of the genoplasm drifting in time: the genorheithrum (1938). Lam also wrote plant-geographical essays on areas with special interest: Talaud, Celebes (1945) and especially New Guinea (1934). As regards his ideas about past connections between Borneo-Philippines-Celebes-Moluccas-New Guinea he owed much to Merrill. Lam was a follower of Wegener’s continental drift theory and he pleaded with fellow taxonomists to accept this as a working hypothesis to explain distribution patterns in the Malesian archipelago (1930). Many of his papers were in Dutch, especially of course those meant for a general (Dutch) public, such as his chapter on phytogeography in Weevers’ book (1939) ‘Het leven der planten’ (The life of plants). He took care, however, to publish his more important ideas in English as well. Among many things Lam will be remembered for initiating a series of distribution maps of Pacific plant taxa: ‘Pacific Plant Areas’, which was to contain critical annotated maps. These should be a valuable asset to botanists, paleontologists, ethnobotanists and others. This plan was first suggested in 1939 during the sixth Pacific Science Congress at Berkeley, but World War II held up execution of the project. As chairman of the ‘Standing Committee on Pacific Plant Areas’ Lam gave a progress report after the war (1953). Realization of the project was to be achieved by Van Steenis, his successor both as director of the Rijksherbarium and as chairman of the Standing Committee.