Japanese chestnut oak (Quercus acutissima )
The Japanese chestnut oak (Quercus acutissima ), also sawn oak or oak silkworm - called, is a deciduous tree species from the genus of oaks.
The Japanese chestnut oak is an up to 30 m tall, deciduous tree. Young branches are 1.5 to 2 mm thick and yellowish- gray tomentose hairs. Verkahlen Older twigs are yellowish- gray and form of lenticels, which have a yellowish- brown color.
The leaves are long, at first tomentose, later balding petioles of 1-3, rarely up to 5 cm. The leaf blade is narrow elliptic- lanceolate, has a length of 8 to 19 cm and a width 2-6 cm. Both leaf pages are colored the same, initially pubescent tomentose, later glabrous completely or only on the veins of the lower leaf surface tomentose. The leaf base is rounded or broadly wedge -shaped; the leaf margin is serrated spine- shaped; the tip acuminate. On each side of midvein are 13 to 18 tributaries, which expire at the perforation of the border. Emanating from the adrenal veins tertiary veins on the underside of leaves slim but plainly visible and more or less parallel.
The acorns develop on the branches of the previous year, either singly or in pairs. Flowering starts in March and April, the fruit is ripe in September-October of next year. The fruit cup is cup-shaped and disc-shaped and has - the bracts included - a diameter of 1.9 to 4.2 cm. The bracts are pfriemförmig to ligulate, about 1.5 cm long, bent back and grayish. The nut is enclosed for half to one- quarter of the fruit cups, it is ovoid to ellipsoid, 1.5 to 2 × 1.7 to 2.2 mm in size, two colors of orange at the base with sliding color transition to green brown on top. The tip of the fruit is pressed, the scar has a diameter of 1 cm and is sublime. The stylopodium has a diameter of about 4 mm and is silky, slightly grayish - brown in color. The fruits are very bitter and are mainly eaten by birds.
The home of the Japanese chestnut oak is located in Korea, Japan, China and the Himalayas. In eastern North America it is very often grown (mostly to wild animals to provide acorns as food available ) and is naturalized there in part; in Central Europe, however, is seldom seen in large gardens and collections this way.
The first description by the English botanist William Carruthers was published in 1862; to the same year, the introduction of the kind in the UK is dated.