Peter Creed of the wildlife trust looks at some intricate tiny green gems of winter

A walk in the countryside in the winter months can be exhilarating; it’s a great way to shed those extra pounds that Christmas always seems to give us, and it can be full of natural surprises. The trees in winter, without their leaves, take on a stark beauty, but take a closer look because they can still be green with life.

Tree trunks and branches can be covered in a green blanket of mosses, and the woodland floor can often be carpeted in green. Why do mosses seem to be at their verdant best at this time of year when most other plants are yet to emerge? The answer is that, unlike flowering plants, mosses are specially adapted to hold on to as much water as possible and to survive for long periods of time without water. Winter is normally a wet season (and don’t we know it!) so mosses take full advantage and soak up and retain as much water as possible. The water is trapped between leaf folds, overlapping leaves and minute hairs. When dry they can be very difficult to see, but a splash of water or, better still, a good soaking will transform them into miniature green gardens.

Crumbling wall tops are another good place for mosses, and many that grow on walls and rocks form tight rounded cushions. This helps them keep warm as well as retaining moisture.

Although these often overlooked little gems are small and mostly of different shades of green, there is a surprising amount of variety in their size, shape and structure. In Oxfordshire we have about 300 different species out of about 800 nationally. BBOWT reserves Sydlings Copse, near Barton, and Dry Sandford Pit, near Abingdon, are especially good for mosses because of the rich and varied habitats that are carefully managed by the wildlife trust. Mosses range in size from the tiny upright pottia (only 1mm tall), often found on chalky soils where rabbits have disturbed the soil near old anthills, to the giant (by moss standards) big shaggy moss, which can grow as tall as 20cm.

Moss leaves can be fine and feathery like tiny ferns, or sharply pointed. Some mosses send up fruiting capsules through winter and spring, often on thread-like stems. The stems can be vibrant red or orange in some species, like the common capillary thread-moss with capsules drooping from the delicate stems in dense patches. Others hold their fruiting capsules tight in among the leaves or just protruding from them. Good examples of this are the bristle-mosses that mostly grow in small tufts or cushions on tree branches. The hooded bristle-moss, quite uncommon in Oxfordshire, likes to grow through rock or walls in areas where it gets splashed, such as weirs and locks on rivers and canals.

Occasionally you’ll find it growing on other structures, such as the old bridge at Culham Lock, near Abingdon. I hope we’ll see this moss on the Small is Beautiful walk to be held at Culham Lock on March 9.

Guided walks are a good way of discovering where these little natural gems are hiding, and how to identify them. This year’s Small is Beautiful moss walks run by BBOWT are fairly close to Oxford.

The first is on Sunday, January 26, at Bernwood Forest, midway between the villages of Stanton St John and Oakley. This is followed by North Leigh Common, near Witney, on Sunday, February 16, and finally the Culham Lock walk on Sunday, March 9. All walks start at 10.30am and last for about two hours. To really get up close and personal, take a hand lens or a magnifying glass. You’ll then start to see the beauty of these miniature plants in more detail.

Take a handy little book: A Guide to Finding Mosses in Berkshire, Buckinghamshire and Oxfordshire covering 200 species, which is available from www.nature bureau.co.uk/bookshop