A modern reference to temperate woody plants
The site
IDS 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. As of October 2025, TSO contains over 14,000 individual articles illustrated by 27,000 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
The text comes from three principal sources: new material specially commissioned for the website; 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 IDS
Trees and Shrubs Online is the flagship project of the International Dendrology Society (IDS), a UK-registered charity with c. 1500 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.
Sponsorship
October 2025: 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 how you can help please write to editor@treesandshrubsonline.org
Recent publications
October 2025: A new account of the spruces (Picea) covers 35 species and over 600 cultivars, making it second only to Hydrangea in terms of scope among all genera revised this year. Another milestone was reached recently when the two Chilean endemics Juania and Jubaea become the first palms to be updated on TSO. Other recent publications include the Chilean bellflowers Lapageria and Philesia, and the conifers Pseudolarix and Pherosphaera. A list of all groups fully updated so far may be found on the Completed Groups page; this is updated whenever a new account is published.
Overall progress has accelerated through 2025 after we welcomed two new staff authors to the TSO team earlier this year. A suite of genera in the Rosaceae have been updated (Kerria, Neviusia, Oemleria, Prinsepia and Rhodotypos) and regular users will notice that older articles have been reorganised to reflect the latest taxonomic thinking, so that old Bean text now appears under the correct name with appropriate synonymy. We will revise these articles in full when funding becomes available. Families have also been updated through 2025 to reflect current understanding.