Sunday, July 28, 2013
Bernheim Forest is one of our favorite places. Sometimes, it seems as if Dick lives there, since he volunteers so many hours, but then, who am I to talk! I haven't been there this summer, and joined Dick at a session led by two of the arborists yesterday. We usually spend our time in the forest, enjoying the native plants and trees, but it is also an Arboretum, where non-native plants are cultivated. In fact, the arborist stressed his enjoyment of the wide variety of trees to be found there, a point of view I don't often hear.
In the winter, we find balls of Mistletoe growing in tree branches, but large thick balls of growth in a tree is called "Witches' Broom," since witches were said to hide their brooms of dense twigs high in a tree during Mideval times. We found them easily visible in both pine and ginko trees. A number of stresses, both biological and environmental, can lead to the formation of brooms. Organisms such as fungi, phytoplasmas (bacterial-like organisms), mites, aphids, and mistletoe plants can cause abnormal growth when they attack a host tree. Environmental stresses that injure the growing points of branches can also trigger the formation of brooms. Some brooms appear to be caused by genetic mutations in the buds of the branches. Unlike brooms caused by living organisms, there is usually just one broom per tree when the cause is a genetic mutation. By either climbing up or shooting samples out of a tree, the broom can be grafted to a normal root, then cultivated, resulting in extremely thick growth that looks like a bush rather than a tree.
Walking over to a particular sweet gum tree, he pulled three leaves from the same branch. One was the normal green, while the other two had developed a variegated coloration. These natural mutations are highly desired by arborists, since they can be cultivated to create new varieties of plants. If the mutation breeds true, Bernheim can then give it a name and sell the new variety. The problem is that after a while, the color variegation can revert to the natural green.
We explored the dwarf evergreen section of the arboretum, finding trees that started as dwarf have outgrown that status now. This little blue spruce has the expected blue needles, but only on the bottom side...
...while bending the branch down for a view of the top reveals the same needles to be green on the top!
Staff shortages can result in surprises sometimes. When a young plant is waiting to be placed in the ground, they are stashed in pots behind the green houses. Recently, one of the interns discovered a little "Franklinia" tree, which is extinct in the wild and no one knew they had it. Our friend Wren was really excited to learn about it. Franklinia is a monotypic genus in the tea plant family. The sole species in this genus is a flowering tree, Franklinia alatamaha, commonly called the Franklin tree, and native to the Altamaha River valley in Georgia in the southeastern United States. It has been extinct in the wild since the early 19th century, but survives as a cultivated ornamental tree.
As much as I enjoyed seeing a different side of Bernheim, I was determined to track down the Bobwhites we heard while eating lunch. It didn't take much of a walk to find two fast running little birds along the roadside. Restoration of the prairies habitat has made a good home for this reintroduced species. It is such a thrill to hear them whistling "Bob-white!"