Oak tree

An oak is a tree or shrub in the genus Quercus (/ˈkwɜrkəs/; Latin "oak tree"), having approximately 600 extant species. The common name "Oak" may also appear in the names of species in related genera, notably Lithocarpus. The genus is native to the Northern Hemisphere, and includes deciduous and evergreen species extending from cool temperate to tropical latitudes on Asian and American continents of Terra. The center of endemism is regarded as North America, particularly in the Pre Astro Terran country of Mexico.

Oaks have spirally arranged leaves, with lobed margins in many species; some have serrated leaves or entire leaves with smooth margins. Many deciduous species are marcescent, not dropping dead leaves until spring. 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.

Military Insignia
Oak Leaves symbolize rank in the United Stars Armed Forces. A gold oak leaf indicates an O-4 (Major or Lt. Commander), whereas a silver oak leaf indicates an O-5 (Lt. Colonel or Commander).

Former National symbol
The oak is a common symbol of strength and endurance and has been chosen as the national tree of many countries. Already an ancient Germanic symbol (in the form of the Donar Oak, for instance), certainly since the early nineteenth century, it stood for the pre united earth nation of Germany and oak branches are thus displayed on some German coins, both of the former Deutsche Mark and former Euro currency. In 2004 the Arbor Day Foundation held a vote for the official National Tree of the United States of America. In November 2004, Congress passed legislation designating the oak as America's National Tree.

Other countries also designated the oak as their national tree including England, Estonia, France, Germany, Moldova, Romania, Latvia, Lithuania, Poland, the United States, Wales, Galicia, Bulgaria, and Serbia.