Green began his botanical career in 1954 as assistant botanist in the
Western Australian Herbarium. He remained in that position until 1958, in his final year serving as botanical adviser to
phytochemical surveys in the
southwest. He then took up a position at the
University of New England at
Armidale, New South Wales until 1963, when he moved to Canberra, initially as an academic, and after 1966 as a researcher at the
Forest Research Institute. In 1970 he moved to
Ontario, Canada, taking up a post as professor at the
Laurentian University. In 1975, Green returned to Australia, taking on the post of
curator to the
Western Australian Herbarium. He held that position until 1987. During this time he oversaw the introduction of
database systems for management of collections. ==Plant taxa publications==