Broadleaf Trees Winter ID Workshop

Speaker: Graham Heffernan

Wednesday 14th February 2024

Number of attendees: 17 adults and 3 children

Following the success of last winter’s conifer workshop by Bruce Brown, Graham led this year’s workshop, bringing in a selection of winter twigs from broad-leaved trees for us to examine. Graham began by giving an introductory talk which included explaining some useful terms and ID features. Graham recommended using The Field Key to Winter Twigs by John Poland, but beginners may also find the guide produced by the Field Studies Council useful. For the dedicated, with money to spend, Graham also recommended Identification of Trees and Shrubs in Winter by Bernd Schulz which is beautifully illustrated. The majority of the evening was spent looking at the specimens that Graham had laid out over several tables, the specimens labelled from A to Z (although specimen E had gone astray somewhere!). Graham set us the challenge of seeing how many we could identify, but warned us that there weren’t necessarily 25 different species. He also told us that he had intentionally made one of the specimens more tricky but said that the location of the next field meeting was a clue. Here are some of the things we learned from the workshop:

Even in mid winter, long before the buds begin to swell, buds on the same twig can be different sizes in some species, such as beech. Some species have flower buds looking very different to leaf buds,  as in the sample of grey poplar we saw.

Some species, such as silver birch, have distinctive tiny dots on the twigs called lenticels which are breathing pores for the tissue below the bark.

Some trees retain last year’s leaves through the winter, a feature known as marcescence (pronounced mar-ses-ence). Marcescent leaves are often seen on young trees of beech and oak and although there are a few theories as to why it happens, such as protection of the leaf buds from winter weather or herbivores, no one knows for sure. Graham thinks it must have an evolutionary advantage as it is seen in unrelated species.

If the buds are in bunches at the shoot tips, you probably have a type of oak or cherry.

Beech and hornbeam look similar, but in beech the lateral buds are held out at a wide angle from the twig, whereas in hornbeam the lateral buds lie more or less flat against the twig.

Willows have only a single scale covering the bud, which comes off as a single unit (a conical cap) as the bud bursts in spring. A specimen of goat willow I looked at confused me as the bud looked like it had a dividing line down the centre, but Graham explained that if I were to tease the bud apart, I would find that they were not overlapping scales and the line is due to the bud scale being formed of two fused modified leaves.

The most common species of Alder has club-shaped purplish buds on stalks whereas Italian Alder has buds more globular in shape and they are greenish, turning reddish-purple.

At the end of the evening, Graham revealed the identity of all the specimens. The tricky specimen with green stems was revealed by Graham to be Holly with the only remaining leaf pulled off! At the beginning of the evening one member had taken a glance at the specimens and declared they all looked the same! Hopefully all who came along are now converts to winter tree identification, with Graham demonstrating just how different the twigs are on closer inspection.

Graham created a handout with some useful ID tips which has been emailed to members.

Text and photos by Susan Simcock