Following Goodspeed’s retirement in the 1950s the Garden directorship passed to Herbert Baker. Under his tenure the collections were further expanded. A seventh expedition, to Bolivia and Peru in 1964, was carried out by garden botanist Paul Hutchison, which added more succulents as well as tropical plants to the collections. Notable additions included major collections from Mesoamerica , Australia and New Zealand , expansion of the Californian native plant collection, and development of a section for economic plants. Baker instituted a major policy change: other than for a few special exceptions all plants accessioned by the Garden must have complete data on their natural origins. Adherence to this policy has endowed the collection with substantial value for researchers world wide.