Standing sentry along the banks of our chalk streams, trees play a crucial role in these ecosystems. Their shade keeps the water cool in summertime, and their roots help to prevent bank erosion. Now that deciduous species have shed their leaves, the complex structures beneath have been revealed. It’s an ideal time to appreciate your streamside trees and improve your identification skills!

Begin your quest by narrowing down the list of options. Trees growing close to streams are likely to prefer damp soil. The wood of alders, for instance, is actually stronger when wet! Other water-loving trees include goat willow, white willow, downy birch, oak, and lime. You could even find a black poplar – once a staple of floodplains, but now a rare sight, in part due to the drainage of land for agriculture.

With your shortlist ready, take in the big picture. The overall shape of a tree is a great clue – most notably the pattern of its branches. Monopodial trees like the black poplar grow in the same direction every year, typically gaining branches on either side. Conversely, sympodial trees like the oak and lime change their growth direction with every new branch, giving them a less uniform ‘zigzag’ appearance.

Next, take a close look at the bark. Trees grow from the inside, and their outer layers respond in ways determined by their composition. The thin layer of the downy birch peels away like paper, while the thick layer of the alder cracks into fissures. Oak and lime bark is pushed up into ridges. But remember that young trees sometimes have smoother bark that will become more uneven with age.

Peering closer still, you may find buds nestled among the branches. Dormant during the winter months, they will become leaves, shoots, and flowers once spring arrives. Goat willows have round, hairless buds, whereas white willow buds are thin and hairy. The grouping is also important – oak buds grow in clusters, but lime buds have an alternating pattern, and black poplar buds form spirals up twigs.

Towards the end of winter, some trees gain a smattering of catkins - flower clusters that will bloom in springtime. On the oak, the male catkins hang from branches in a long, yellow curtain. The catkins of the white willow look like brushes, but become fluffy once pollinated. The alder has long red-yellow catkins alongside small, round cones that can be green or brown in colour.

If you need a little help with your tree ID, the Woodland Trust have a free app that works with bark, buds, and branches; perfect for wintertime. Or if you’d like to learn more about the wonderful world of chalk streams, you can explore the Watercress and Winterbournes scheme - these complex ecosystems are some of our most biodiverse habitats, but need our help to thrive.