January 2009 Archives

I had been starting to feel like a proper winter; cold, dry air, no winds, several inches of frost into the ground, sunny days and brilliant, starlit nights.
Alas we are now back to the wet, wind and penetrating damp chill.
A few winter-flowering shrubs are making a brave attempt. Winter jasmines gallantly hang on to their bright yellow petals and some daffodils have opened in sheltered corners. They are heartening sights.
The bare trees are now at their most inactive. For me they now hold a special fascination because much of their growth history is told in their stark shapes.
Good growth seasons with long, straight growth steps, poor seasons with stunted, twisted internodes.
Damage from storms and the impacts of human activities are recorded in the scars on their trunks and branches. They can survive extreme conditions, and still manage to grow in waste soils confined between tarmac and walls.
The capacity of trees to absorb damage is impressive. A main strategy is growing new tissues around the wounded site, so the damage is isolated and encapsulated within the tree.
Some types of damage produce bizarre growth patterns. Witches brooming is particularly strange. It manifests as clumps of proliferating side shoots, which look completely out of place on otherwise healthy looking trees.
Witches brooming occurs on birch, cherry, beech and sometimes ash. It also occurs commonly on shrubs such as gooseberry, forsythia and honeysuckle.
The brooming is thought to be caused by physical damage to the growing shoots, which causes a local increase in side-shoots. Possible causes for the damage include aphids, mites and other insects, fungi, bacteria, salt (from roadside spray as well as the sea) and air-borne toxic chemicals.
The amazing shapes into which trees and shrubs can become contorted are worth looking at.
It's worth taking a quick picture of anything unusual. Send it to me at the Herald and we can post it up for others to see.