Identification of Plants, including Trees

• Wild plants are one of our specialities, especially if they are British or European wild flowers. We have the necessary reference library (Floras), but for more exotic plants we sometimes need to consult a specialist collection of pressed, dried herbarium specimens. For on-site identification we can probably recommend a local specialist. For naming cultivated plants it is advisable to have specimens identified at such establishments as Kew Gardens or the Royal Horticultural Society Gardens at Wisley, as they have the huge collections available for comparison purposes. So we rarely look at garden flowers! 
• In a more applied field, we undertake a lot of identification of twigs and other tree samples from urban sites. Our findings can be of value to developers and surveyors (who are expected to pronounce in a field far outside their own expertise), and particularly in investigations in connection with cases where trees are allegedly involved in structural damage. For example, some of our root identification clients also append twigs, which they ask us to match to their root samples (following our objective identification of the roots), to provide an authoritative, integrated report.
• We identify twigs in summer and winter, from a length of twig bearing buds and/or leaves. Summer material within some groups of closely related trees is indistinguishable without flowers and/or fruits - particularly for some fruit trees, or conifers in the cypress group.  The potential for winter identification of deciduous twigs comes as a surprise to some.  However, much is possible, at least to the level of genus (eg. to Oak (Quercus) though not to English Oak (Quercus robur); or to Hazel (Corylus), though not to Turkish Hazel (Corylus colurna)). These identifications are based mainly on morphological observations (surprisingly, and unlike roots, microscopic structure is of little help in characterising twigs).
• Our book Tree Recognition: A Pocket Manual provides guidance on methods for obtaining appropriate samples. Specimens in leaf should either be pressed for 24-48 hours between sheets of newspaper, then in a cardboard folder, or else placed immediately after collection in dry polythene bags and quickly sent in a protective box.
• Sometimes a good photograph can give added information in tree identification - especially for some conifers. Indeed we are at times able to provide ‘instant’ guidance from an emailed or even faxed twig!
• We also undertake some wood identification (though not tropical timber), either from garden stumps or from structures; a cubic centimetre of wood is adequate. We occasionally comment on annual growth-ring patterns, but we do not carry out any structural tests on timber samples. Neither do we attempt identification of disease in trees or timber; contact The Timber Research and Development Association for such enquiries.