Plant Index

A modern reference to temperate woody plants

The site

Trees and Shrubs Online 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 and of New Trees, 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 twenty-first century that will make this the pre-eminent resource for anyone interested in trees and shrubs. The day to day project management, including editorial oversight of all new text, is the responsibility of the Editorial Team.

The text

Currently, the bulk of the text is derived from two sources. The 'Bean' text is from the Eighth Edition, the last to be published, which appeared in four volumes during the 1970s, along with the Supplement, published in 1988. New Trees was published in 2009 and sought to cover all the new introductions to cultivation from the period from the Eighth Edition to c. 2005.

Bringing all entries up to date is a large, complex, and long-term project. Some major genera, such as Rhododendron and Quercus, will need to be published incrementally, while others will be revised in full as funding becomes available. Many groups have already been revised (see Completed Groups), and an international team of authors is constantly at work preparing new entries.


Trees and Shrubs Online has been made possible by the International Dendrology Society, a truly international organisation with c. 1500 members in 50 countries. Since its inception the IDS has been dedicated to its charitable aim of advancing the knowledge of woody plants around the world. The idea for TSO was born out of the success of New Trees, itself an IDS project, and since the website’s launch 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 countries all around the world, and everyone involved in TSO looks forward to seeing these figures increase further.

TSO logo Sponsorship

Trees and Shrubs Online relies on generous donations to meet its core costs, and sponsorship to enable new text to be researched, written, and published. The project is indebted to the many individuals, organisations, and charities which have contributed generously to our aim of disseminating new, high-quality information, for free, for everyone.

With so much work still ahead you can help by sponsoring a genus or a family, or by donating in general support of this important project. We are currently seeking sponsors for the genus Acer, especially the many so-called Japanese Maples of Section Palmata, as well as sections of other major genera such as Rhododendron, and significant conifer genera, too. To enquire about sponsoring these or other groups, or supporting the project in any way, please write to

TSO logo Recent publications

November 2023: Work on Trees and Shrubs Online has continued steadily over the past few months, with numerous authors actively producing new text. Two of the more complex genera to be updated recently include Podocarpus and Lindera, published in July and August respectively after many months’ work researching and writing.

Further new texts to appear recently include the genera Desfontainia, Glyptostrobus, Kalopanax, Pseudotsuga and Zelkova.

Accounts nearing completion in late 2023 include North American maples (Acer spp.), Embothrium, Sassafras and Sequoia.

A list of all groups fully revised to date can be found on the Completed Groups page; this is updated whenever a new account is published.