The creators of Sydney's botanic garden were a varied group of people with diverse agendas and interests, only some of whom saw themselves as men of science. While several were trying to advance botany, others were more concerned with self-advancement or financial gain. Yet they collaborated, almost unintentionally, to found Australia's first scientific institution. Exchanges of plants were crucial to forming and maintaining the relationships between these different figures. Studying these exchanges allows hitherto neglected figures to take their place in the garden's story alongside well-known ones. This study also takes issue with the notion that British colonial botanic gardens were established as part of a botanical empire, with Kew Gardens at its centre. It also seeks to extend Susan Leigh Star and James R. Griesemer's idea of ‘boundary objects’, by suggesting that relationships based on barter, gift-exchange or patronage rather than cash played a key role in mediating between the participants in colonial scientific institutions.