Diminishing degrees of uncertainty in plant identification

Plant identification in the field will always seem to throw up more questions than answers when you begin your journey of learning plants useful for Bushcraft and Wilderness Survival. I strongly believe that it is important to develop a good system to help you on the right pathway of learning. To quote the famous detective Sherlock Holmes “it is a process of elimination my dear Watson!”

On a recent course I was delivering, my fellow instructor and I had a tree present itself that we could not immediately identify. Here is the process that we went through to gain our identification.

It certainly helped to have two brains thinking it through but the process of elimination would be the same if you were on your own. Think General Impression of Size and Shape (GISS) and then apply that to the plant, location and other flora in the immediate vicinity.

My first general impression was that the leaf looked Oak like whereas the other thought was Sorbus. So immediately we both began to question our initial thoughts. The leaves seemed really large for an Oak, but it was located on the edge of a ride and could have been larger due to growing for the light. Compared to a nearby Oak they seemed massive!

It was suggested that it could be the Wild Service tree Sorbus torminalis, but there was no sign of berries remaining on the tree or the ground. This seemed less likely, but interestingly there was no sign of acorns on the ground either! Could the bark of the tree be the deciding factor perhaps? The degrees of uncertainty seemed to be diminishing but it was not clear cut yet!

You would expect the bark of an Oak to be deeply fissured and rough in texture, but as you can see from the image below the bark is smooth and not a fissure in sight.

The mystery was not yet resolved. Could it be that the diagnosis of Oak was now under question when it seemed to be so convincing? Tree bark does change as a tree matures and it is very true that a juvenile tree bark can look very different to a mature trees bark. Was this the case here or was there another clue that need exploring? I grew up learning tree identification in the winter and always remember the cluster of stubby buds typical of Oaks. This surely had to be the final piece of the puzzle!

Close scrutiny of the bud formation showed a positive identification of Oak. The classic, stubby, cluster of buds was there to prove the case.

This is Quercus robur / Pedunculate Oak. Interestingly it gets its name from the stalk that the acorns hang from that is called a peduncle. The other native Oak to the United Kingdom is Quercus petraea / Sessile Oak and is distinguished because the acorn forms at the leaf, it has no stalk. This photo has lots of the information for a positive identification and on looking at the bark this is complete.

So we have identified our specimen to be an Oak, but we still need to discover which one. The size of the leaf leads me to think it is a non-native that is being grown for its potential timber production as it is growing in an area of woodland in Derbyshire managed for timber. We suspect it to be Quercus rubra / Red Oak, native to Eastern USA and South East Canada. On looking it up this is a positive identification. Interestingly according to The New Silva by Gabriel Hemery & Sarah Simblet the red oak does not produce viable seed in the UK except in the south of England and it is more shade tolerant than the native Oaks. This all adds up as it was planted on the edge of a block of trees and produced no acorns in its location in the North of England. It is also being used in timber production. A good result and a new tree learnt.

Plant identification when you are not sure is always the diminishing degrees of uncertainty. It is good practice to get into good habits of questioning to help you. Here the process was applied to a tree identification but this can easily be adapted to perennials too. Seasonality, stages of growth and family characteristics will then come into play much more, but that is a topic for another time.