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Just imagine the gall of that Gaul to take a large bite out of a gall. These words, which are pronounced the same, are unrelated to one another. A synonym for the first word could be "audacity." The second is a descendent from those pesky tribes who once irritated the Roman Empire, and the final one is a remarkable plant growth created through genetic reengineering.

Most of us are familiar with the large round galls on oak trees -- the so-called oak apples. But there are thousands of different kinds of galls. A gall is basically an abnormal growth on a plant. This can result from physical damage caused by branches rubbing together, or an invasion of mistletoe or bacteria. But most are created by the action of insects. An insect lays eggs in the host. The eggs hatch into larvae and the larvae release a complex porridge of chemicals. These chemicals in turn redirect the growth of the plant's tissue into an entirely new pattern. The resulting galls are so unique in character that simply the shape of the gall can identify the species of parasitic insect. The gall provides sustenance for the developing larva, which pupates into a winged adult who then eats its way out of the gall and the cycle begins anew.

An extract from galls -- gallic acid -- has been used for centuries to make permanent inks. The U.S. Constitution for example was written with iron gall ink. This chemical has also been used as a dye and medicinally as an antiseptic skin treatment.

Most gall-making insects are neutral in their economic impact. However there are two notable exceptions. The first one is positive -- members of one gall wasp family are the only pollinators of figs. The negative is the disease that nearly wiped out the entire European grape industry in the late 1800s -- phylloxera -- is caused by another gall insect.

California is rich in gall diversity. Next time you are out hiking, take a minute to find and appreciate these natural marvels. They are easily seen on oaks and manzanitas.


This is Michael Ellis with a Perspective.