A Field Key to Lichens on Trees contains 128 colour photographs and illustrated keys. These keys use only characters that are visible in the field, by eye, or under a ×10 hand lens. This combination enables the user to identify over 500 species of lichens which are likely to be found on trees. There is also a supplementary key to 'Lichens on sawn wood' (such as posts, fences or benches). All the species descriptions include a distribution map for the British Isles.
A Field Key to Lichens on Trees gives information for three methods of identification:
(Method 1) The simplest method is just to compare the specimen with the 128 coloured photographs of the commoner species.
(Method 2) The identification may be made by using the colour photographs together with the detailed table of characters to these 128 species.
(Method 3) Use of the more advanced keys that includes just over 500 species covering most of the species which can be identified in the field. For ease of use, the key is divided into sections relating to their growth form. It is fully illustrated throughout with numerous line drawings of the more important features that are used in the key. Identification is assisted by a distribution map for the British Isles. If this key does not produce a result, the descriptions of rarer species may be consulted. If the lichen occurs on sawn or worked timber this may be consulted first.
The use of technical words is kept to a minimum and an illustrated glossary is provided. A Field Key to Lichens on Trees