About
IDS Trees and Shrubs Online (TSO) is the International Dendrology Society’s ambitious project to create a truly modern reference to temperate trees and shrubs. Currently (October 2025) there are articles for some 850 genera, over 5,000 species, and approximately 8,300 subspecies, forms and cultivars. These articles are illustrated by over 27,000 published images.
The text comes from three principle sources: new material specially commissioned for TSO; the text of New Trees by John Grimshaw and Ross Bayton, commissioned by the International Dendrology Society and published by Kew Publishing in 2009, and W.J. Bean’s Trees and Shrubs Hardy in the British Isles, first published in 1914. The ‘Bean’ text used on the website is from the Eighth Edition, the last to be published, which appeared in four volumes between 1976–1981, along with the Supplement by Desmond Clarke, published in 1988.
Much of the historic material, especially the ‘Bean’ text, is particularly dated. Measurements are in imperial, many of the specimens Bean cited are no longer extant, and the horticultural experience has changed enormously. This is true not least in the context of climate change, but also in the diversity of woody plants being grown in gardens, which is greater now than ever before. Furthermore, Bean restricted the geographical scope of his work to the British Isles, whereas TSO is concerned with all the temperate zones of the world. Even so, no subsequent work has ever been of sufficient scope to stand as a natural successor to Bean, until now.
As funding becomes available, TSO commissions specialist authors to produce new accounts that will replace historic text. To date, over 160 genera have been updated - a list of these is maintained on the completed groups page. This is an enormous achievement, but the task ahead is greater still. Our aspiration is for each new account on TSO to be the best horticultural monograph of the genus available, and very well illustrated. TSO is a unique resource, already the largest ever horticultural reference work, building on published literature to create a reference relevant to the 21st century with all its challenges.
To complete its work TSO is reliant on generous donations to cover core costs, and sponsorship to enable new accounts to be commissioned. If you might be interested in sponsoring a genus or supporting the project in any other way, please do contact us through info@treesandshrubsonline.org.
TSO is the flagship project of the International Dendrology Society (IDS), a charity registered in England and Wales (number 1178252). The IDS is dedicated to promoting the knowledge of trees and shrubs and is pleased to be able to stand behind this important project.
Using the site
The articles are organised alphabetically by genus, and then by species within each genus.
There are two main ways to find articles: you can use the Plant Index page to find genera and species organised alphabetically, or you can use one of the search features.
To search, use the Search box on the Home page or select Advanced Search for further options.
On pages with genus articles, there are links for the species in that genus; these links will open the individual species articles. Within species articles links to the other species within the same genus are provided, as well as infraspecific articles including subspecies, varieties and cultivars.
To find plants in a particular family, use Advanced Search page. Searching for a family will largely return a list of genera within that family; these articles contain links to the species.
Credits
The use of material from Bean’s Trees and Shrubs has been enabled by the generosity of the publisher, Hachette UK (formerly John Murray), and the holders of the copyright in the text from the Bean and Clarke families.
The site is produced by Arkesis Ltd and designed by Andreja Brulc.