Winter Tree ID

A couple of weeks ago I came home to my new housemate Joel (who is also a colleague and general non house or work related wonderful friend) reading Colin Tudge’s ‘The Secret Life of Trees’ on the sofa. Joel is obsessively bookish, which is great because it means that by sharing a house with him, I am essentially living in a private library. He told me that he wanted to learn more about trees and when I mentioned that I had booked myself on to a Winter Tree ID course at Attenborough Nature Reserve, he decided to come along too.

So last Saturday morning we headed off to Attenborough; my local nature reserve since the move. It was kind of a grey, chilly morning but the Nature Centre was warm and we arrived to a full classroom and fresh coffee. There is always an interesting mix of people attending these Wildlife Trust run courses and today was no exception: I caught up with a couple of people who I had met on previous courses; a plant scientist with an ecology degree and a NWT conservation volunteer. It’s great to have people of all ages in attendance and a mix of those with an academic interest and those who simply have a passion for gardening and/or the outdoors. I suppose that at the moment I fall somewhere in between the two, and I think Joel just likes knowing things – any things.

Our teacher for the day was Angelena, a trainee ranger at Attenborough and someone I’ve known a while through various volunteering activities, courses and social groups including Nottingham Bat Group. She’s fantastic at public speaking (she led the bat walk at Attenborough that I wrote about a few months ago) and I was really impressed with the way she delivered the course – maybe one day when I’m more experienced I’ll be able to emulate this 🙂 She began with a presentation which covered some of the features we would use to identify deciduous trees without leaf, namely the anatomy of twigs, including bark and buds. We had several specimens which we spent the morning keying out (using a fantastic FSC book) – mostly successfully but we did get stuck on occasion. Listed below is some of the key terminology that I learned on the day…

  • Terminal buds – these are the buds at the very end of a twig and extend past the tip of the stem.They can be arranged singularly, in pairs or in clusters.
  • Axillary buds – buds on the stem before the tip. Again these are found as singular or clustered, and are positioned along the twig as either opposite, alternate or spiralling.
  • Lenticels – one of my new favourite words! The lenticels are like the pores of the tree and are instrumental in gas exchange between the inner bark of the tree and the atmosphere. Lenticel shape is a distinguishing feature in some trees, for example in Wild Cherry (Prunus avium) lenticels appear as characteristic horizontal stripes in the bark.
  • Leaf scar – when a leaf falls from a twig, a ‘scar’ is left. The shape of these leaf scars can help you distinguish between different species, for example they are heart shaped in walnut trees, but shield shaped in ash.
  • Bundle scar – bundle scars are found within the leaf scar and show the remnants of the vascular bundle when the leaf was attached to the tree.
  • Bud scales – these are modified leaves which cover and protect developing buds. The number of bud scales, any pubscence (hairs) and/or stickiness are useful to note when identifying trees. On older twigs, previous years growth appears as bud scale scars, which we realised can easily be misidentified as a bud stem if you’re not an expert in twig ID.
  • Pith – spongy tissue found within the stem. It is either continuous or chambered (as in walnut species).

Hawthorn (Crataegus monogyna) caught nearly everyone out, as although Angelena assured us there were no Blackthorn (Prunus spinosa) samples present (due to the very high risk of infection if a thorn injury is sustained), we somehow all managed to key it to that instead.

After a lunch courtesy of the wonderful Nature Centre Café  our class headed out on to the reserve to put some of our new found skills into practice. While learning the anatomy and nomenclature we needed to follow the key, we had also picked up a lot of simple identification skills that are useful in the field. The colour of a bud is hopefully easy to recognise and when taken into account with bark colour/texture can allow quick and reliable identification in some species e.g;

Common Ash (Fraxinus excelsior) has distinctive black buds, smooth bark in young trees/diamond patterned in more mature trees and with ‘keys’ (winged seeds that hang like bunches of keys);

Sycamore (Acer pseudoplatanus) has bright green buds, in combination with smooth bark and ‘helicopter’ seeds;

Horse-chesnut (Aesculus hippocastanum) should be easily identifiable by a very sticky, large, single terminal bud;

Alder (Alnus glutinosa) has grey-purple boxing glove shaped buds, pendulous purple/green catkins and reddish-purple twigs with orange lenticels. Female catkins later develop into woody cones.

A recurring topic of conversation throughout the day surrounded the controversial spine/thorn/prickle terminology. I don’t think that anyone who attended this course will forget that, contrary to many popular expressions, roses have ‘prickles’ not thorns, even if they can’t remember what exactly the difference is. In fact, I’ve just had to look it up again  (Joel would have remembered but he’s not here), but I’ve found a useful description on this gardening website.

Simply put, prickles grow from the outer layer of the stem and are not vascularly connected to the twig. Thorns are modified stems whereas spines are modified leaf parts. Confused? I am, especially as one of the keys we were looking at on the course seemed to use ‘thorn’ and ‘spine’ without distinction. I have been assured however, that each of these terms constitutes a different identifiable feature on plants.

The difference between thorns, spines and prickles was discussed alot! This FSC key describes wild roses as having ‘thorns’, but it should be ‘prickles’.

The next day we confidently named a number of different tree species on campus (next stop Latin names?) and talked to friends about the course and some tree ID tips.  Joel said that Saturday made him take a bit more notice of the things around him, which I love and I hope he will pass on to others. I learned a lot on this course, from the simple identifying features I’ve described above to more complicated tiny physical structures that can only be seen through a hand-lens. I know that I’ll be able to use this knowledge whenever I’m out and about, whether I’m walking along a tree lined city avenues or in the midst of a mixed deciduous woodland.

All images subject to copyright. All opinions expressed on this site are my own and don’t necessarily represent the view of Nottinghamshire Wildlife Trust for whom I volunteer, or any other organisation.

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