The live ginkgo, the tree can be more than 30 meters tall with a diameter at breast height of more than 3 meters. Under suitable conditions, ginkgo can grow into a high-quality timber with a straight, rounded trunk and little sharpness. A suitable ecological environment is the basis for ensuring that the ginkgo grows into a high-quality timber with a small degree of sharpness. In one of the starting place in zhejiang province linan county west tianmu mountain ginkgo, there are tall money pine and other forest accompanied, plus mountain humus loose and fertile, so, plant growth more prosperous, trunk straight, from the ground, at least more than ten meters long trunk, almost up and down general thick. 90 years old adult tree, tree height 23-26 meters, single plant volume of 1 cubic meters, and still in the peak growth of volume of lumber. In the peak growth period of the volume of wood.
In the isolated wood state of the ginkgo, as well as the north (such as Liaoning) or south (such as Guangdong) distribution of the ginkgo, the general height of the main trunk branches less than 2 meters, the main trunk of the upper and lower thick and thin disparity, especially in the fork of the backbone of the branch up and down, the difference is more prominent. This is due to plant growth inhibited by various factors. Nearly whorled trunk branches, sometimes the growth of the main trunk is greatly inhibited. This situation, although extremely unfavorable to the production of high-quality wood, but in favor of the plant's flowering and fruiting.
The xylem of ginkgo consists of rounded tubular cells with marginal pores. Some of the thin-walled cells contain large calcium oxalate crystals, which become reddish in appearance, with very undeveloped rays and distinct annual rings. Ginkgo's cortex is thicker, with small rhombic or elliptical lenticels, and the outer epidermis is generally cracked in strips or small patches, slightly crossed to varying degrees.
There are a large number of cryptic buds on the main stem of the ginkgo. Short branches sprouting from these cryptic buds can sometimes flower and bear fruit. Under certain conditions, these stable buds will also develop and expand, forming rows of tumor-like projections. At the base of the main branches or at the bends of large branches, these projections are stalactitic and are commonly called "breasts", "silver breasts" or "tree breasts". The largest breasts seen are more than 2.0 m long and have a basal diameter greater than 28 cm (Guizhou). At the base of the trunk, this bulge expands horizontally to form a tumor, which is called a "chair" by the public. Sometimes a row of horizontally arranged wart-like projections can be seen on the main trunk, also developed from the adventitious buds of the ginkgo. It is different from the emulsion of the tree in that it does not have an obvious orientation to the ground. The mechanism that produces this bulge is not clear, and the preliminary inference is that it may be related to the growth inhibition of the plant.
Ginkgo's female and male plants can produce tree milk, but the proportion of female plants producing tree milk is significantly higher than that of male plants. Therefore, the masses have "ginkgo only grows tree milk and chair, can bear fruit".
In fact, not only large trees can grow tree milk, even one or two-year-old seedlings, and even just sown two months of sprouts, in the root growth is hindered or other specific conditions, the root stem below the part, can also grow small tumors; on the contrary, has entered the fruiting period of the adult ginkgo are not all plants can grow tree milk. Therefore, the argument that the formation of endosperm is a sign of entering the fruiting stage is unfounded. Whether it is possible to make an early identification of ginkgo fruiting and even other traits from the difficulty of producing tree milk, it is also worth doing some in-depth research. For the formation of tree milk, there is still a lack of unified understanding. Some people think it is a physiological phenomenon, pointing out that this is a primitive trait, is the origin of the early residual species **** there. Some people think that the formation of endosperm may be related to the thickness of the bark. Thin peripheral bark is prone to produce endosperm. Others believe that this is a pathological phenomenon, is the ginkgo biloba organization by some kind of exogenous stimulation, only to grow out of the tumor. However, they have not conclusively demonstrated exactly what kind of microorganisms are responsible for the formation of tree milk.
The growth of tree latex is distinctly ground-oriented. It roots quickly as soon as it touches the ground. Isolated tree endosperm can grow roots in less than a month when cultivated under the right conditions. These facts tell us that tree milk is aerial rooting. This view is further confirmed by the fact that tree milk can be induced in large quantities when the ginkgo tree is drastically cut and its root growth suppressed.
Dissection of the newly formed endosperm reveals several circles of circular cavities arranged along the endosperm cortex. The cavities are filled with purple pulp, and their structure is similar to that of the radicle tissue. Nutritional analysis of the endosperm tissue reveals that it contains a large amount of starch. All this shows that it is more reasonable to judge it as an aerial root tissue.
The endosperm of adult trees grows on the trunk of the branch, often in the corner of the branch drooping. These areas, where water droplets tend to collect, are also where organic nutrients transported downward tend to accumulate. This creates conditions for adventitious root formation and growth from both inside and outside the tree. Growth is impeded by a humid climate, which encourages the production of such adventitious roots even more, and this is the source of the regional differences in the formation of tree milk.
Scientists have determined the content of important organic components in the root apricot wood, mannan content of 7.06%, galactan content of 1.87%, raw wood methoxy content of 2.41%, air-dried wood methoxy content of 4.55%, dry wood methoxy content of 5.20%. The tannin content of ginkgo bark was 10.0%, and the coloring degree was 1.17.
In the oxidation products obtained from ginkgo sapwood, endodermis and exodermis oxidized with nitrobenzene in alkaline medium, the highest content was vanillin, followed by p-hydroxybenzaldehyde and p-hydroxyazobenzene, and there were also a small amount of vanillin acid, butyraldehyde of formyl vanillin acid and so on.