In Tim Entwisle’s forthcoming book*, Three Worlds Oak, a dying hybrid oak in Melbourne’s Royal Botanic Gardens sets off on a search for its parents, and in doing so reveals the extraordinary diversity of the genus Quercus.

From the Himalaya to Mexico, from knee-high scrub to rainforest giants, more than four hundred species of oak shape landscapes, cultures and histories. Their leaves can blaze red and gold, acorns can be the size of a hand, and while only a few cross the equator to the south others survive in mountains to 4,000 metres. Tim will illustrate his presentation with illustrations by his wife (and active AGHS member) Lynda Entwisle, as well as photographs of oaks in their natural settings. Tim wants to remind us there is far more to oaks than the familiar English tree, and to invite us to look anew at some of the world’s most beloved plants.

Light refreshments will be served after the lecture.

About Tim Entwisle

Professor Tim Entwisle AO was Chief Executive of Royal Botanic Gardens Victoria for ten years, two years in a senior role at Royal Botanic Gardens Kew in London, and eight as head of Royal Botanic Gardens and Domain Trust in Sydney. He is currently Chair of the Harbour Trust in Sydney and an Acting Commissioner with the Land and Environment Court of NSW.

Tim has a broad interest in algae, plants and public gardens, contributing regularly to Australian radio, print and social media. His memoir Evergreen: the Botanical Life of a Plant Punk was published by Thames & Hudson in 2022, and a collection of essays, The Sceptical Botanist, by CSIRO Publishing in August 2025. Three Worlds Oak will be published by Reaktion Books in the UK in September 2026, and available in Australia later in the year.

*Due out in Australia in December 2026, you can preorder from booksellers listed by the local distributor NewSouth Books.