A modern reference to temperate woody plants
Trees and Shrubs Online
IDS Trees and Shrubs Online (TSO) is the International Dendrology Society’s ambitious project to create a modern, web-based encyclopaedia of cultivated woody plants hardy in the temperate parts of the world. As of April 2026, TSO contains over 16,000 individual articles illustrated by over 30,500 images, all freely available to anyone, anywhere with an internet connection.
TSO provides comprehensive ‘biographies’ for each plant it covers, detailing botanical aspects, identification information, cultural history and horticultural experience. This is a unique resource, already the largest ever horticultural reference work, building on published literature to create a resource fit for the 21st century with all its challenges. Our work is funded by philanthropic giving. The day to day project management, including oversight of all new text, is the responsibility of the Editorial Team.
The text
Our text comes from three principal sources: new material specially commissioned for Trees and Shrubs Online; the text of New Trees by John Grimshaw and Ross Bayton, published in 2009; and W.J. Bean’s Trees and Shrubs Hardy in the British Isles (8th edition, published in four volumes between 1976–1981, with a 1988 supplement). Much of the historic material, especially the ‘Bean’ text, is particularly dated, and our aim is to renew this entirely.
This is a large, complex, and long-term project but so far over 160 genera have been completely re-written thanks to the generous support of many donors. Every article is meticulously researched and carefully edited to ensure reliability, and an international team of authors is constantly at work preparing new entries. As an active website, flexibility is an integral attribute, permitting regular updates to be made whenever new information or images are available.
The International Dendrology Society
Trees and Shrubs Online is the flagship project of the International Dendrology Society (IDS), a UK-registered charity with c. 1600 members in 50 countries. Since it was founded in 1952 the IDS has been dedicated to its aim of advancing the knowledge and study of woody plants around the world, and bringing together dendrologists of all backgrounds. The idea for TSO was born out of the success of the publication New Trees, itself an IDS project, and since launching TSO the IDS has worked to raise funds to support the project’s ongoing work.
These efforts are now being rewarded by the tens of thousands of unique visits to TSO every month, from users all around the world, and everyone involved in TSO looks forward to seeing these figures increase further.
Support TSO
May 2026: IDS Trees and Shrubs Online relies on generous donations to meet its core costs and sponsorship to enable new text to be researched, written, edited and published. We are indebted to the many individuals, organisations and charities that have contributed to date, enabling us to disseminate new, high-quality information for free, for everyone.
Since expanding our core team in early 2025 progress has accelerated, but we continue to rely on new sponsorships to maintain momentum. We would be delighted to hear from anybody interested in supporting our ongoing work. We are particularly keen to secure funding to update the Japanese maples, and any of a diverse suite of genera that are enjoying a surge in popularity, but which are poorly served by existing horticultural literature, such as Heptapleurum (formerly Schefflera) and many of its relatives in Araliaceae.
To find out about sponsorship opportunities please write to info@treesandshrubsonline.org
Recent publications
May 2026: A new account of the dogwoods, Cornus, went live on TSO to coincide with the start of the 2026 RHS Chelsea Flower Show. The new account covers over 50 species and nearly 900 cultivars of this diverse and hugely important genus which, in one guise or another, features prominently in gardens throughout the temperate world.
Cornus follows hot on the heels of another major milestone for TSO, the cultivated red oaks (Quercus Subgenus Quercus Section Lobatae) covering over 100 species and hybrids and over 80 cultivars, by far the most comprehensive account of these important trees ever published. A full list of new oak articles may be found on the Quercus genus page. Other recent publications include the sweetshrubs, Calycanthus, and a range of different Asiatic maples – see the maple genus page for a list of recent updates in Acer.
A list of all groups fully updated to date may be found on the Completed Groups page which is updated whenever a new account is published.