A collection of wildlife photographs

Thursday, 3 April 2014

Winter tree identification

On the 15th Februay, I went to a winter tree identification course with Sheffield Wildlife Trust http://www.wildsheffield.com/ I didn't take any photographs on the day, but on a recent walk out to Rivelin on 21/03/14 I noticed that the majority of trees had yet to sprout leaves from their buds.

The first tree I noticed by the section of the river Don, was an Ash, Fraxinus excelsior. Ash trees have complex terminal buds (i.e. the buds growing from the end of the twig are arranged in a cluster). The buds of Ash are a sooty black colour, and tend to be rounded, apart from the more cone-shaped terminal buds. The lateral buds (the buds that grow from the side of the twig) are arranged in opposite pairs, as shown in the photograph below. This means that the leaves produced by the buds of Ash trees, in late April-May, are also produced in opposite pairs along the twig.
Ash, Fraxinus excelsior

Alder, Alnus glutinosa
Further along the river, I found many Alder, Alnus glutinosa trees. This is hardly surprising because of their affinity for water. Alder has spectacular mauve buds, which are described as being 'club' or 'boxing glove' shaped. The buds are positioned on scaly stalks, extending from the twig, as shown in the photograph below, and lateral buds are organised alternately along the stem. The bark of alder trees can be purply-brown, darkening to grey-brown with age, but generally bark is not the most reliable diagnostic identification feature of trees.
Alder, Alnus glutinosa
Hazel, Corylus avellana

The picture on the right displays the twig of a Hazel, Corylus avellana tree. Hazel is usually found in hedges and beneath the canopy of larger trees. They are relatively tolerant of the shade. The buds on Hazel trees in the winter are short and brown, typically with green-red scales, which unfold as the leaves sprout in March-April time. Hazel has very hairy twigs, which can be a useful feature for identification.

Although Elder, Sambucus nigra plants appear to be remarkably shrub-like, they are formally classified as trees. The ecologist at Greno Woods, described them as a 'teenager's messy room' in their growth habit. Elder's buds are purply-brown and covered in spiky scales. These buds are particularly small, and arranged in opposite pairs. At the time of taking the photograph below, the lateral buds were beginning to produce leaves. Elder trees are mostly found in clearings, hedgerows and scrub.
Elder, Sambucus nigra
The photograph below is of an Oak tree, Quercus sp., because of the hairless twig and buds. Oak produces a complex 'cluster' of terminal buds at the end of its twigs, and the twigs are reasonably straight. The bark on these twigs is dark brown and shiny, and often covered in pale warts. It can be difficult to tell apart Pedunculate oak, Quercus robur and Sessile oak, Quercus petraea from their buds alone. 

Oak, Quercus sp

Using the buds to identify trees in the winter can be useful. Other important diagnostic features include the tree outline. For example, the drooping twigs of Silver Birch, Betula pendula can easily be told apart from the erect twigs of the Downy Birch, Betula pubescens. There is still time to spot leafless deciduous trees this season, but as trees produce leaves, identification will become even easier.

No comments:

Post a Comment

Sign up