Categories for Winter

Dormancy Onset In Trees

October 16, 2019 By , ,

The nights are quickly becoming longer in the northern hemisphere and the average temperatures are dropping, triggering dormancy in trees. Dormancy is a winter weather survival mechanism in which tree shoot growth is significantly reduced to protect soft tissues from freezing temperatures. In the fall, the decreasing daylight triggers the production of abscisic acid, a hormone that impedes growth. Abscisic... Read More

Tree Line

January 14, 2019 By , , ,

The snow-covered peak of Mount Hood dominates the eastern skyline of Portland in the winter. From a distance, it looks as though there is a sharp line above which trees do not grow. The elevation above which trees do not grow is called the tree line and is at about 6,000 feet on Mount Hood, or about the elevation of... Read More

Tree Anatomy: Growth Buds

March 14, 2018 By , ,

After a long, dark winter, the swelling buds on bare branches foretell the coming of an eagerly anticipated spring for many Portland area residents.  A bud is an undeveloped part of the plant.  Flower buds become blossoms, whereas growth buds develop into shoots. Growth buds are the teardrop-shaped parts of the tree where new growth occurs.  A branch grows longer... Read More