Dr M’s Autumn Term botany class #1: Of apps and keys and trees and shrubs

Dr M’s first lesson with MSc Plant Diversity students and MSc SISS included a tour round the woodland known as the Wilderness on the University of Reading award-winning green campus.

One objective of this first class was to collect samples of trees and shrubs during a short ramble through the woods and take these back to the laboratory to ID using three different ID aids.

(1) Field Studies Council key to winter twigs;

(2) Natural History Museum Interactive guide to common woody plants of the UK; and

(3) Leafsnap UK.

Three dustbin bags containing over thirty species were collected including trees and shrubs and woody climbers and although most or these were native species there were some non-native naturalised and planted species.

The first task was to sort the pile of leaves and twigs from the three dustbin bags into genera in the lab!

Now, Dr M’s Vegetation Survey and Assessment class includes experienced botanists as well as new and beginning botanists, so an important element is learning the terminology which botanists use to name the numerous different bits and pieces on plants which help separate them into families, genera and species.

The plethora of botanical terms can be daunting, even off-putting, to the newcomers to field botany, but since most of the tools needed to ID plants use this terminology there is no alternative but to grit the teeth and bite the bullet (if that’s possible through gritted teeth) and learn it!

Dr M encourages each student to compile their own glossary in their field notebook as they progress through the term, and there are plenty of great aids to help them along the way, such as the Kew Plant Glossary – an illustrated dictionary of plant terms by Henk Beentje and illustrated by Juliet Williamson.

In this first lesson Dr M’s students learned about:

(1) Opposite or alternate leaf arrangement – always a first step in plant ID – especially when vegetative characters are to the fore;

(2) Leaves and leaflets and how to tell the difference – rather crucial if you’re going to get anywhere near the right answer in the key!;

(3) Simple and compound leaves which can be entire (no teeth on the margin) or with a serrated margin (teeth!);

(4) Compound leaves which show a variety of forms including pinnate and palmately divided;

(5) Stipules which are additional, sometimes leaf-like, appendages paired at the base of the leaf stalk (aka petiole) and which help ID certain families such as Fabaceae (Pea family) and Salicaceae (Willow family);

(6) Leaf buds and scales – the number of scales on the leaf buds is a useful character and sometime there may be many, as in Oaks, or few as in Willow and Alder.

All these terms helped students work the plants through the NHM interactive key which helps identify trees, shrubs and woody climbers found in the wild in the UK, whether native or introduced and includes 465 taxa.

Wherever possible, the key concentrates on characters of the leaves, since these are the easiest parts of the plant to obtain. Although useful, flowers and fruits are only available for short periods. They often occur on the higher branches where they are out of reach. If using fruits that have fallen from the tree make sure they come from that plant you are studying and not from a different individual nearby.

Here are the main species (excluding confers) that Dr M’s field botany class collected and identified during the day:

(1) Those with simple, opposite leaves:

Three species with palmately lobed deciduous leaves (Acer – Maples) one with small simple evergreen leaves (Buxus – Box):

Check the University of Reading’s own Whiteknights Biodiversity blog post all about mysterious maples here!

(2) Those with simple alternate leaves – all those here with lobed leaves

 

(3) Those with alternate leaves – those here have unlobed leaves, but often with serrations (teeth – which can be sharp or rounded or indistinct depending on the species) along the margin: 

(4) Those with compound (either palmate or pinnate) opposite leaves:

 

(5) Those with compound (again either palmate or pinnate) alternate leaves:

Leafsnap UK: One of the aids the class used, Leafsnap UK, is a free App which requires no more effort than taking a picture of the leaf  against a white background (the “leaf snap”). Then the App does the work for you by coming up with a list of possible ID’s based on the leaf dimensions and the suggested answers can be perused as high res images in the App database.

Dr M was keen to check this App since the UK it originated with Leafsnap in the USA and the UK version, Leafsnap UK, has only recently been launched.

After the session Dr M “leafsnapped” the thirty-one trees and shrubs in the lab and found that nineteen (61%) were successfully ID’d by Leafsnap UK. though in some cases it was necessary to try several leaves before the correct answer came out as the first suggestion (e.g. Horse Chestnut and Sycamore).

For six other species the correct solution was listed but not at the top sometimes way down (e.g. False Acacia and Hornbeam).

For seven species the correct answer was not in the list at all (e.g. Bramble, Ivy and Grey Willow). Maybe Leafsnap UK does not include climbing shrubs and some non-native species (e.g. Walnut and Rhododendron did not work), though it is not obvious how to find the list of species included in Leafsnap UK!

Leafsnap UK and learning field botany: Leafsnap UK is a very useful additional aid to tree and shrub ID and it’s good to have the UK version which hopefully will continue to be updated to include more and more native and introduced species.

However Leafsnap UK relies on snapping an image of the leaf and checking this in the database and there is only limited learning which comes from this.  Although repeated use can instill some learning of why each leaf fits the species it does.

In contrast traditional botanical keys, whether hard copy or online versions, ask you the user successive questions (couplets) which force you to really look at the plant and check the important characters for ID.

Keys help you learn about the plant so that when you encounter it again you are much more likely to recognise it and also you will learn which characters to look for to identify new species that you find.

Dr M concludes:  Use Leafsnap UK by all means, but always supplement by cross-checking with a key and reading the scientific description of the plant in the books. Field botany is not just about getting the answer it is understanding WHY it is the right answer! 

Post script from the makers of Leafsnap UK:

Dr M says: The Natural History Museum provides the following tips for getting the best results from the Leafsnap UK  App:

Leafsnap UK uses cutting-edge visual recognition technology to match the shape of your leaf photo to thousands of leaf images in its database.

Leaves, light conditions and photo style can vary, so here’s how to get the best results.

1. Look for a leaf that is representative of others on the tree, that is as flat and undamaged as possible, particularly around the edges.

2. Pick it carefully along with its leafstalk or petiole.

3. Place the leaf face up or down on a white background, a smooth piece of paper or cloth is best. The flatter the leaf, the better.

4. Take a photograph:

• from directly above the leaf with your iPhone parallel to it
• outside in even light, shade is better than sunshine, avoid dappled light
• with as little shadow around the leaf as possible

The leaf should be as big as possible without touching the edges of the screen. Check:

• the whole background is white and a white border surrounds the leaf
• no hands, fingers or anything else are visible in the picture
• the leaf is in focus, particularly the leaf edges or margins

Compound leaf of the common ash.

Compound leaves
Photograph the whole leaf rather than individual leaflets. Compound leaves are leaves with a number of leaflets attached to the leaf stalk or petiole. The leaf of the common ash (Fraxinus excelsior), shown here, is a good example.

Browse leaves in Leafsnap UK to see high-res examples.