Oak apple due to the superficial resemblance and the preponderance of the oak marble gall in the wild. Other galls found on oak trees include the oak artichoke gall and the acorn cup gall, but each of these has its own distinctive form. Some common oak-apple-forming species are the "Biorhiza pallida" gall wasp in Europe, "Amphibolips confluenta" in eastern North America, and "Atrusca bella" in western North America. Oak apples may be brownish, yellowish, greenish, pinkish, or reddish. Oak galls have been used in the production of ink since at least the time of the Roman Empire. From the Middle Ages to
Royal Oak, Michigan with 7,147 employees, The City of Royal Oak with 465 employees, Royal Oak Public Schools with 482 employees, Oakland Community College with 448 employees, Consumers Energy with 351 employees, Flex-N-Gate with 350 employees, the Detroit Zoo with 301 employees, Holiday Market with 300 employees, and HHI- Form Tech with 290 employees. The city is served by Royal Oak Neighborhood Schools. There is also a private high school, Shrine Catholic. A branch of Oakland Community College is located in the city. A portion of land in the city is zoned to Berkley Public Schools. In recent years Royal Oak has begun