Oaks have spirally arranged leaves, with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. The flowers are catkins, produced in spring. The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6–18 months to mature, depending on species. The live oaks are distinguished for being evergreen, but are not actually a distinct group and instead are dispersed across the genus.
Oak has always been respected by nearly all world cultures. Admired for its strength and size it represents strength, endurance and power. Because it is often struck by lightening it has become associated with having the ability to attract inspiration, wisdom and illumination. Oak galls were known as Serpent Eggs and were used in magic and charms. It has also been associated with fertility. The oak is considered very sacred to the druids and there name has even been linked as a derivative of duir (oak).