Trees and Shrubs Online

By Dr John Grimshaw, Director of Yorkshire Arboretum

Trees and Shrubs Online (TSO – is the International Dendrology Society’s ambitious project to create a modern, web-based encyclopaedia of woody plants hardy in the temperate parts of the world. The website was launched on a core of data formed from the full text of Bean’s Trees and Shrubs Hardy in the British Isles (eighth edition, published in four volumes during the 1970s) and of New Trees, published in 2009, making these seminal texts freely available to anyone, anywhere with an internet connection.

The long-term aim of the project is to renew these texts entirely, creating a fresh body of information for the 21st century that will make this the pre-eminent resource for anyone interested in woody plants. As of December 2020 TSO contains over 11,000 individual articles. Many groups are still in their Bean format, some combine text from Bean and from New Trees, and as funding is secured to commission revisions, genera are brought fully up to date. The Editor-in-Chief is Dr John Grimshaw, Director of the Yorkshire Arboretum, with Tom Christian as Deputy Editor

Many groups have already been revised in full and new, modern accounts published online in recent months. These include novelties usually restricted to botanic gardens and specialist collections such as Carya, Emmenopterys, and Fitzroya, but also a great many horticultural stalwarts including several sections of the genus Acer, notably the snakebarks (Section Macrantha) as well as Araucaria, Cedrus, Davidia, Fagus, Juglans, Kolkwitzia, woody Paeonia, Stewartia, Styrax, Tilia, and Weigela.

Major genera like Quercus and Magnolia are being tackled in manageable bites and published incrementally. At the time of writing, in late 2020, the first batch of oaks (Section Ilex) is nearing completion, and revisions of several other important genera are well underway, including Abies, Buddleja, Cornus, and Nothofagus. All new accounts published on TSO include an overview of the genus, scientific descriptions of each species known to be in cultivation, and as in the original Bean volumes a horticultural commentary discussing important introductions, horticultural requirements, and significant examples. A thorough representation of cultivars is discussed, too. In large genera keys are also provided. We hope to be able to illustrate all entries eventually, but this is a particularly large challenge; please contact us if you could supply good quality, informative images.

The whole resource is available for free at – wherever there is a connection to the internet!

Contact: John Grimshaw (