galls are the balls that grow on oak trees.
what are the balls that grow on oak trees?
galls
oak apple or oak gall is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. oak apples range in size from in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family cynipidae. the adult female wasp lays single eggs in developing leaf buds. the wasp larvae feed on the gall tissue resulting from their secretions, which modify the oak bud into the gall, a structure that protects the developing larvae until they undergo metamorphosis into adults. considerable confusion exists in the general "literature" between the oak apple and the oak marble gall. the oak marble is frequently called the 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.
oak apple
oaks are keystone species in a wide range of habitats from mediterranean semi-desert to subtropical rainforest. for example, oak trees are important components of hardwood forests, and certain species are particularly known to grow in associations with members of the ericaceae in oak–heath forests. a number of kinds of truffles, including the two well known varieties, the black périgord truffle and the white piedmont truffle, have symbiotic relationships with oak trees. similarly many other mushrooms such as "ramaria flavosaponaria" also associate with oaks. the european pied flycatcher is an example of an animal species that often depends upon oak trees.
oak