As the national tree of many westerncountries in the world, the oak tree is undoubtedly the king of trees. Mostspecies of the oak trees are deciduous and marcescent, which means its lobed orserrated leaves will grow and wither with the change of seasons but the deadleaves will not drop until spring.

Oak trees are usually large in size, with amaximum of 70 feet in height and 9 feet in width. It usually has a thick trunkgrowing upright to the sky and many branches extending out toward the top, forminga magnificent canopy. With such dimensions, it would not sustain without a largeconsumption of water every day. As the result, its roots grow both downward andoutward desperately to form a board root system.

When the tree reaches about 20 years old,it will start to bloom and self-pollinate, in other words, in spring, a singleoak tree can produce both male and female flowers. The male flowers, calledcatkins, spread a great amount of pollen which clouds the air of mid-April. Incontrast, the female flowers keep a rather low profile by hiding among the twigs.The fruit of the oak trees is called acorn and it is no stranger to you. Rememberthe nut chased by Scrat in the movie Ice Age? That’s it. The nut containstannic acid, which protect it from the attack of fungi and insects. It oftentakes 1 or 2 years for an acorn to mature and drop from its parental tree.

On average, the life expectancy of the treecan be 200 years while some species can survive for 600 or even 800 years.