What to plant for Bark and stem

The flaming oranges and reds of cornus; the tactile papery white trunk of Acer griseum… Winter brings unexpected benefits, says Anne Swithinbank

- Anne Swithinbank

FOR me, a great way of limbering up before a stint of leaf raking or compost spreading is to stride about the garden, homing in on specific areas that illustrate the joys of the season. Winter has the effect of stripping bare; however, it also brings to the fore twiggy outlines and the extraordinary colours and textures of stem and bark. For most of the year these are masked by an abundance of summer growth; but choose the right trees and shrubs, and from leaf fall to spring, gardens come alive with snaking fissures, waxy lenticels and glowing stem tips.

The beauty of bark

Of course, this performance is not played out primarily for our benefit; it has evolved to help trees live long lives and to adapt plants to their natural habitats. Tree bark forms a protective outer coating, shielding the inner workings of trunk and branches from scorching hot sun, drying winds, freezing cold, fire, and grazing animals. Just inside lies the phloem, which transports sugars from leaves to the rest of the tree, then a cambial (or cell producing) layer and, further in, the active xylem, moving water and nutrients from the roots. At the core is old xylem, or heartwood. The role of colour in stems is less well understood, but it’s thought to help with the absorption of light, or with protecting tissues from it.

Bark is every bit as fascinating as it is beautiful. Explore the chunky, platelike coating of mature pine trees, the sponginess of cork oak, and curling ribbons from river birch and paperbark maple. Look for swathes of fresh colour exposed as large sheets fall from the stems of eucalyptus, and feel for raised lenticels: the porous areas enabling an exchange of oxygen, carbon dioxide and water vapour.

The role of pruning