Accurate life span of Davidia involucrata

Latin scientific name: Davidia involucrata

Alias: water pear, pigeon tree, pigeon flower tree.

Family and genus: Davidia involucrata.

Endangered category: rare

Protection level: This species has been listed as a national key protected wild plant (approved by the State Council1August 4, 1999).

Deciduous trees, which can grow to 20-25 meters high, have broad oval leaves and serrated edges. There is only one genus and two species of undergraduate plants, and the two species are similar, but one has hairy leaves and the other is smooth. This is a remnant plant.

[Edit this paragraph] Morphological characteristics

Davidia involucrata is a deciduous tree with a height of 20 meters.

This kind of tree is a deciduous tree, and its bark falls off irregularly in thin slices. Simple leaves alternate, clustered on short branches, the leaves are papery, broadly ovate or nearly heart-shaped, the apex is acuminate, the base is heart-shaped, the edge is coarsely serrated, the petiole is 4-5 cm long, and the flowers are mixed. The terminal flower head consists of most male flowers and an bisexual flower. There are two white bracts under the inflorescence, paper-shaped, oval, 8- 15 cm long, serrated below the middle, and the drupe is purple-green, which blooms in April and ripens in 10.

Davidia involucrata has purplish red flowers, which are composed of most male flowers and one bisexual flower. It is like a pigeon's head, with "eyes" and "mouth". The two large white bracts at the base of the inflorescence are like a pair of wings of a pigeon. From April to May, when Davidia involucrata blooms, white bracts float in the green leaves, just like thousands of white doves perching on the treetops and flapping their wings.

Liriodendron chinense, a rare plant endemic to China.

The scientific name is Liriodendron chinense. )Sarg。

English name Chinese tulip tree

Alias jacket, double floating tree

Classification of Liriodendron in Magnoliaceae.

National second-class key protected wild plants (approved by the State Council 1999)

Magnoliaceae is an ancient angiosperm, which distributed in northern Europe, Greenland and Alaska with higher latitudes in the northern hemisphere from the middle Cretaceous to the early and middle Tertiary. In Cenozoic and Tertiary, it is widely distributed in Eurasia and North America. After the Quaternary Glacier, it only distributed in southern China and southeastern United States (both belong to the same species) and became relict plant.

Therefore, Liriodendron chinense and Liriodendron chinense are very old tree species, which is of great significance for studying the relationship between the flora of East Asia and the flora of North America, and for discussing the geological and climate changes in the northern hemisphere.

Deciduous tree, height 40 meters, DBH 1 meter. Leaves alternate, 4- 18 cm long and 5- 19 cm wide, with 2 lobes on each side and white surface on the back; Petiole is 4-8 cm long. The shape of the leaves is like a jacket-the top of the leaves is flat, like the hem of a jacket; The sides of the blade are smooth or slightly curved, like the waist of a jacket; The two sides of the blade protrude outward, like two sleeves sticking out of a jacket. So Liriodendron is also called Liriodendron. The flower has a solitary branch top, 9 perianth segments, 3 calyx-shaped outer wheels, green, petal-shaped yellow-green inner wheels, and yellow stripes at the base, which are similar to tulips. So its English name is "Tulip Tree in China", which translates into "Tulip Tree in China" in Chinese. There are many stamens and many pistils. Aggregate fruit is spindle-shaped, 6-8cm long and1.5-2cm in diameter. Nutlets have wings and are 2.5-3.5 cm long.

Key points of cultivation

It is suitable for cultivating deep, fertile, well-drained acidic and slightly acidic soil, and likes warm, humid and sunny environment. Cold tolerance, semi-shade tolerance, drought tolerance and moisture tolerance, and suitable growth temperature 15? 25 degrees Celsius, winter capacity? Low temperature 17℃.

use

It is a very precious bonsai ornamental plant, very rare.

It can resist toxic gases such as sulfur dioxide and can be planted in areas with serious air pollution.

Bark is used as medicine to dispel wind and remove dampness.

The protection level belongs to the national second-class protected plants.

Liriodendron chinense mainly grows in the south of the Yangtze River Basin, and its distribution area starts from qingtian county, Zhejiang Province in the east, Jinping County, Yunnan Province in the west, Ziyang County, Shaanxi Province in the north, Jinping County, Yunnan Province in the south and northern Vietnam in the south. Most of them grow sporadically in low mountains between 600-1500m above sea level. According to the investigation, Liriodendron plants are naturally distributed in 84 counties in China 1 1 province, including Jiangsu, Anhui, Zhejiang, Fujian, Hubei, Hunan, Guangxi, Shaanxi, Sichuan, Guizhou and Yunnan. , but generally scattered in the east, south-central, relatively concentrated in the west.

Liriodendron and hybrid Liriodendron have been planted in Henan, Hubei, Hunan, Shandong, Shaanxi, Beijing and other provinces and cities, and generally grow well. For example, the height of the 25-year-old Liriodendron introduced and planted in Shangcheng County, Henan Province has reached 25m and DBH is 35cm, and the height of the 3-year-old Liriodendron introduced in Xi 'an Botanical Garden is 2.55m and the ground diameter is 3.6cm, which can safely survive the winter. Seven Liriodendron hybrid families introduced from Nanjing Forestry University grew well in Hanshou County, Hunan Province. The average tree height of 10 is15.0/-15.42 m, the average DBH is 24.73-26.65 cm, and the average individual volume is 0.3374-0.400. The hybrid Liriodendron introduced by Beijing Botanical Garden and China Academy of Forestry not only grows well, but also blooms normally. All above indicate that Liriodendron chinense and hybrid Liriodendron chinense are suitable for planting, which is far beyond the original natural distribution area of basil.

Endangered reasons Under natural conditions, the seed plumpness rate of Liriodendron chinense is generally less than 15%, while the seed germination rate is only below 5%. There are many reasons for this low seed setting rate.

Liriodendron is an insect-borne flowering plant, but its color is monotonous and its petals are green, which makes it unattractive to most insects. The flowering period is usually in April-May, which coincides with the rainy season in the Yangtze River basin. The temperature changes greatly, and the occasional low temperature hinders the normal activities of insects, which often affects the spread and fertilization of pollen and reduces the natural seed setting rate. Fan Ruwen, Yin Zengfang and Zhou Jian systematically observed the flower bud differentiation and fruit ripening of Liriodendron. Liriodendron is a monoecious plant, usually the pistil matures before the petals unfold, but the stamens are not mature at this time, and there is a self-pollination isolation mechanism; After the petals are unfolded, the stigma quickly turns brown and the receptivity is very short. The abortion of male and female gametes is common, and there are some phenomena such as the growth of pollen tube is blocked and the development of embryo and endosperm is uncoordinated. Therefore, the reproductive biological obstacle is the main reason for the low seed setting rate and endangerment of Liriodendron chinense.

In addition to the above-mentioned flower structure specialization and genetic obstacles in the process of fertilization, the natural seed setting rate is greatly reduced, the existing population reaches a very small scale, and the resource allocation is unreasonable. Long-term outcrossing will inevitably accumulate a large number of recessive harmful genes in the gene pool, the inbreeding coefficient among individuals in the population will increase, and self-pollination and genetic drift will also affect the viability of the population. According to the analysis of seed isoenzymes of Liriodendron by Parkws and Wendell, the genetic diversity of Liriodendron in China is lower than that of Liriodendron in North America. These also affect the natural seed setting rate to some extent.

From the ecological point of view, how many people think that the original suitable environment has been seriously damaged, and Liriodendron has been in an unsuitable habitat for a long time, which is also one of the reasons why this species is endangered.

Zhu Xiaoqin and others think that most populations of Liriodendron are in unfavorable habitats, but they still have a high level of genetic diversity, so comprehensive measures should be taken to protect an endangered species with complex genetic structure. First of all, we should stop deforestation, try to preserve the existing population and individuals, and create a more suitable habitat on the basis of in-situ protection. It can also be considered that ex-situ migration has created a large population and a large space, provided conditions for gene exchange and recombination of this species, and reduced the genetic diversity of isolated small populations caused by genetic drift and inbreeding. Wang also believes that the protection of genetic resources of Liriodendron chinense in China should focus on ex situ conservation, and suggests that appropriate sites should be selected in East China, South Central China and Southwest China to establish gene banks respectively to preserve the existing natural resources in China, and at the same time, select excellent populations and take measures to artificially promote natural regeneration for in situ conservation. It is also necessary to carry out mating among populations, promote gene exchange and broaden the genetic basis of this tree species.

As early as 1930s, Liriodendron chinense was introduced and cultivated in Nanjing, Kunming, Qingdao, Lushan, Hangzhou, Shanghai and other places in China, but the quantity was very small. 199 1 year Liriodendron chinense is the main tree species in the national afforestation project loaned by the World Bank. For the first time, several provenances of Liriodendron chinense in southern China were introduced on a large scale, and geographical provenance tests were carried out in the whole distribution area. According to reports from Li Jianmin, the provenance test results of Liriodendron americana in Shaowu Experimental Site in Fujian Province show that the root system of Liriodendron americana is underdeveloped, and the survival rate and preservation rate of artificial afforestation are not high. After afforestation, the plant mortality rate is higher than that of Liriodendron chinense, and large-scale afforestation is always difficult to succeed. They believe that the purpose of introducing Liriodendron is to enrich the resources of interspecific hybridization breeding, not to enrich the afforestation trees in this area. Among the five experimental provenances of Liriodendron chinense, the inland provenance is the best and can be used as the parent population of interspecific hybrid breeding.

1963 Professor Ye Pei, a famous breeder in China, used a Liriodendron from North America introduced to the Ming Tombs in the 1930s to cross Liriodendron from China. After more than 30 years and several generations' efforts, it has been proved that Liriodendron North America and Liriodendron China are compatible, and the hybrid Liriodendron North America not only retains the unique leaf shape of its parents, but also has strong heterosis. It also has excellent characteristics such as larger than the compatible leaves, more colors, faster growth, stronger stress resistance, wide adaptability, almost no pests and diseases, and is an excellent landscaping tree species. At the same time, it is also an excellent timber tree species for pulp and paper, plywood and other industrial raw materials. Hybrid Liriodendron has been planted in Fujian, Zhejiang, Jiangsu, Hunan, Hubei, Henan, Shandong, Shaanxi, Beijing and other places in China, showing strong adaptability. With the improvement of people's living standards and the greening and beautification of the environment, especially the success of Beijing's bid for the Olympic Games, it is expected that the demand will increase sharply in recent years, and the contradiction between supply and demand has become very prominent, with a large gap between supply and demand.

However, due to the limitation of parent materials for hybrid seed production of Liriodendron chinense, the low seed setting rate of artificial hybridization (only about 30%), and immature asexual propagation techniques such as cutting and tissue culture are still in the experimental stage. The industrialization process of hybrid Liriodendron chinense has been curbed. Solving the above problems is always a top priority. Accelerating the development of hybrid Liriodendron is the need of landscaping and improving the ecological environment, the need of the market, the need of protecting the genetic resources of endangered Liriodendron in China, and a career with broad development prospects.