The systematics and cultural history of economically significant plants.
The history of science and of botanical illustration.
The extraordinary story of the apple (due August 2019), with Dr B.E. Juniper (University of Oxford UK)
The Robert Brown Handbook (due September 2019), with David Moore (deceased) and Jacek Wajer (Natural History Museum London)
A revision of the huanglongbing (citrus greening) host genera Bergera and Murraya (Rutaceae), with Prof. Andrew Beattie and team (Western Sydney University)
A revision of the genus Citrus (Rutaceae)
A review of pre-Darwinian European encounters with the Australian flora (due November 2019)
A revision of Dysoxylum sensu lato (Meliaceae), with Prof. Dr. Alexandra Muelnner and team (University of Leipzig, Germany)
The genetics of Linnaeus’s apple (Rosaceae), with Dr D. Chagne (Plant and Food, Palmerston North, New Zealand)
Mabberley’s Plant-book ed. 5
Editor, Cultural History of Plants, a multivolume work (Bloomsbury, London), with Prof. A. Gieseke (University of Delaware)