Oak is the largest flowering plant in the world; Life is very long, it has a life span of 400 years. The fruit is nuts, one end is hairy and the other end is bare, which is the first-class food for squirrels and other animals. It is found that a Jurupa oak tree in California, USA has survived for at least 6.5438+0.3 million years, which may be the oldest known creature in the world.
On April 30th, 20001,the American Arbor Day Foundation announced that the oak tree was selected as the national tree of the United States through online voting.
Deciduous or evergreen trees, up to 25 to 30 meters high. The bark is dark grayish brown and slightly smooth. Branchlets brown and glabrous. Winter buds are ovoid, 3~5 mm long, hairless, with dark brown bud scales, mostly covered by tiles. The leaves are oval or oval, with a length of 10 ~ 20cm and a width of 7 ~ 10cm. The top is tapered, the base is wedge-shaped, and there are 5~7 pinnate splits on each side of the leaf margin. Lobes have finely divided teeth, leaves are dark green, abaxial surface is light green, and vein axils are hairless or tufted. Petiole 2.5~5 cm long, glabrous when old.
Male inflorescence and leaves open at the same time, forming several clusters; Female flowers are solitary or have 2~3 flowers on the total stem about 1 cm long.
The shell bucket is cup-shaped, with cover nut 1/ 4~ 1/ 3, diameter 1.5~ 1.8 cm and height 1~ 1.2 cm. Bracteoles triangular, closely imbricate, glabrous and shiny. Nuts are oblong, with a diameter of about 65438 0.5 cm and a height of 2~2.5 cm. They are light brown, covered with thin fluff, and then gradually fall off. The top is round and has a small column seat; Fruit navel flat or slightly concave. The flowering period is from April to May, and the fruiting period is September of the following year. Native to the United States. This species is waterproof and moistureproof. Nuts contain starch 46. 1%, tannin 10.6%, oil 12.6% and protein 7.4%.