Alpine Willow Over Volcanic Rock
by Michele Penner
Title
Alpine Willow Over Volcanic Rock
Artist
Michele Penner
Medium
Photograph - Photograph
Description
Image of an alpine willow leaning over a volcanic rock along a creek in the eastern Cascade Mountains in Oregon. What looks like red berries on the willow are actually sawfly galls. See below for details.
Willow Leaf Gall:
"A leaf gall is an unusual growth of plant’s cells on leaves. The galls
are usually formed on the younger leaves and galls develop into the leaves as
they grow. They appear to be green lumps and then later in the season the will
turn brown or red. The galls are oval and about 6 mm long. There may be only
one or several galls on a single twig or leaf. In general, the leaf galls do not
cause serious problems to the plant. They are just very unsightly when in large
numbers on the plant.
Cause: The cause of the willow leaf gall is a Redgall Sawfly, or scientifically
known as Pontania proxima, a type of primitive wasp. As the tree’s leaves are
expanding the adult sawflies insert the eggs into the expanding tissues in early
June. A single female is able to lay up to 50 eggs. This is what causes the leaf to
swell into a lump or chamber, which nourishes and protects the developing grub.
Most of them emerge by fall and over winter in a cocoon in the leaf litter on the
surrounding ground. There is only one generation per year." Katie Sailor,
University of Idaho
Uploaded
September 29th, 2016
Statistics
Viewed 102 Times - Last Visitor from New York, NY on 04/13/2024 at 4:36 PM
Embed
Share
Sales Sheet