Characteristics of ginkgo tree

The branches of Ginkgo biloba are tall and straight. When young, the bark is shallow and light gray. With the growth of tree age, cracks and colors gradually become deeper. The shape and length of cracks are obviously different among plants. From strip to cross, the length varies from 40 cm to 100 cm.

Ginkgo biloba, the height of the tree can exceed 30 meters, and the diameter at breast height exceeds 3 meters. Under suitable conditions, Ginkgo biloba can grow into high-quality wood with straight and complete trunk and small taper. The suitable ecological environment is the basis to ensure that Ginkgo biloba grows into high-quality small sharp wood. Ginkgo biloba, one of the first places in Xi Tianmu Mountain, Lin 'an County, Zhejiang Province, is accompanied by tall trees such as Pinus bungeana, and the humus soil in the mountain is loose and fertile. Therefore, plants grow more vigorously and the trunk is straight. From the ground, there are at least ten meters long trunks, almost as thick as the top and bottom. The 90-year-old tree is 23-26 meters high, and the volume per plant is about 1 m3, which is still at the peak of volume growth.

Ginkgo biloba in isolation, as well as Ginkgo biloba distributed in the north (such as Liaoning) or south (such as Guangdong), generally the height of branches on the trunk is less than 2 meters, and the thickness of the trunk varies greatly, especially the upper and lower branches of the branches. This is due to the inhibition of plant growth by various factors. Trunk branches near the whorl sometimes greatly inhibit the growth of trunk. Although this situation is extremely unfavorable to the production of high-quality wood, it is beneficial to the flowering and fruiting of plants.

The xylem of Ginkgo biloba consists of round tracheids with marginal holes. Some parenchyma cells have large calcium oxalate crystals, which are red in appearance, extremely underdeveloped in radiation and have obvious annual rings. Ginkgo biloba has a thick cortex with small diamond-shaped or oval lenticels, and the outer skin is generally split into strips or small blocks with a slight degree of crossing.

There are many hidden buds on the trunk of ginkgo biloba. Short branches that grow from these hidden buds can sometimes blossom and bear fruit. Under certain conditions, these stable buds will develop and expand, forming rows of tumor-like protrusions. At the base of the main branch or the bend of the big branch, this kind of protrusion is bell-shaped, commonly known as the largest tree milk seen by "milk", "silver milk" or "tree milk", with a length of more than 2.0 meters and a base diameter of 28 cm (Guizhou). At the base of the trunk, this protrusion extends laterally to form a tumor, which is called "chair" by the masses. Sometimes you can see rows of horizontal verrucous protrusions on the trunk, which are also developed from the adventitious buds of Ginkgo biloba. Unlike tree milk, it does not see obvious geotropism. The mechanism of this uplift is not clear, which may be related to the inhibition of plant growth.

Both male and female plants of Ginkgo biloba can produce tree milk, but the proportion of female plants producing tree milk is obviously higher than that of male plants. Therefore, there is a saying among the masses that "Ginkgo biloba can only be strong if it grows tree milk and chairs".

In fact, not only big trees can grow tree milk, but even one-or two-year-old seedlings or even two-month-old buds can grow small tumors below the roots or under other specific conditions. On the contrary, not all adult ginkgo trees entering the fruiting period can grow tree milk. Therefore, it is unfounded to take the formation of tree milk as a sign of entering the fruiting period. It is also worth doing some in-depth research on whether it is possible to identify the fruit setting and other traits of Ginkgo biloba early from the difficulty of producing tree milk. At present, there is no unified understanding of the formation of tree milk. Some people think it is a physiological phenomenon, pointing out that it is a primitive trait, which is possessed by residual species with earlier origin. Some people think that the formation of tree milk may be related to the thickness of bark. Thin skin tends to produce tree milk. Some people think that this is a pathological phenomenon, and the ginkgo tissue is stimulated by some external factors to grow tumors. However, they did not confirm what kind of microorganisms caused the formation of tree milk.

The growth of tree milk has obvious geotropism. It can take root quickly as soon as it touches the ground. The test-tube tree milk can grow roots in less than a month under suitable conditions. These facts tell us that tree milk is aerial root. This view is further confirmed by the fact that ginkgo trees can induce a large number of tree milk when cutting roots and inhibiting root growth.

When dissecting the newly formed tree milk, we can see several circles of circular cavities arranged along the cortex of the tree milk. The cavity is filled with purple pulp, and its structure is similar to that of radicle. The nutritional analysis of tree milk tissue shows that it contains a lot of starch. All these indicate that it is reasonable to judge it as aerial rooting tissue.

The milk from the trunk of an adult branch is often in the drooping corner of the branch. In these parts, water droplets often gather, and organic nutrients transported downward are also easy to accumulate in these places. This creates conditions for the formation and growth of adventitious roots from both internal and external aspects of the tree. The growth is hindered, and the humid climate is more conducive to the generation of this adventitious root, which is also the root of the regional difference in the formation of tree milk.

Scientists have determined the content of important organic components in root apricot wood. Mannan content is 7.06%, galactan content is 65438 0.87%, log methoxy content is 2.465438 0%, air-dried wood methoxy content is 4.55%, and dried wood methoxy content is 5.20%. The tannin content of ginkgo bark is 10.0%, and the coloring degree is 1. 17.

Among the oxidation products obtained by oxidation of sapwood, endothelium and shell of Ginkgo biloba with nitrobenzene in alkaline medium, the highest content is vanillin, followed by p-hydroxybenzaldehyde and p-hydroxy azobenzene, and a small amount of vanillic acid, formyl vanillic acid syringaldehyde and so on.