How to Grow Yew? An Introduction to the Cultivation Methods of This Anti-Cancer Medicinal Plant
Yew is recognized worldwide as a rare, endangered natural anti-cancer plant and holds an important medicinal position in pharmacology around the world. So how should this yew be grown?
With the continuous development of modern medicine, cancer is no longer called an "incurable disease" as it was when we were young. In addition to improvements in medical technology, the discovery of anti-cancer medicinal plants has also contributed to cancer treatment. Yew is recognized worldwide as a rare, endangered natural anti-cancer plant and holds an important medicinal position in pharmacology around the world. So how should this yew be grown? Below we will look at the cultivation methods for yew.
I. Introduction to Yew
In 1994, yew was designated by China as a first-class rare and endangered protected plant, and it is also called a "national treasure" by all 42 countries around the world that have yew. It is truly a "plant giant panda."
The reason yew has anti-cancer medicinal value is mainly that it contains a substance called taxol. Taxol is an anti-tumor active ingredient with significant efficacy in treating metastatic ovarian cancer, breast cancer, lung cancer and esophageal cancer.
II. Yew Cultivation Methods
1. Seed propagation
Seed propagation is one of the most commonly used methods for growing yew. Seed propagation mainly goes through the steps of seed collection, storage, germination promotion, sowing, nursery site selection and management. For southern yew, seed collection is mainly in late October each year. The collected seeds should be piled and retted for 4-6 days, the outer seed coat washed off, the waxy layer rubbed off, disinfected by soaking in potassium permanganate, then dried and stored. When promoting germination, soak the seeds in warm water, then place the seeds in a prepared germination pit. The germination time is about 7 to 12 days, by which time the seeds should have cracked.
Yew is best sown by broadcasting. After broadcasting the seeds, cover them with plant ash and yellow subsoil. Southern yew seedlings are relatively shade-tolerant, so the nursery site must have a gentle slope, deep and fertile soil, and good drainage and irrigation conditions. About one month after sowing, yew seedlings will basically all emerge. At this time, when managing yew, pay attention to fertilizing the yew. Fertilizing 5 to 6 times a year is enough.
2. Cutting propagation
This is also one of the cultivation methods for yew, though not many people use it. For yew cutting propagation, softwood cuttings in spring and hardwood cuttings in autumn are best. To ensure the survival rate of yew, low-frame shading treatment is generally required during cutting, and the shading rate must not be lower than 60%. The most important part of yew cutting propagation is the rooting treatment of the yew. The growing humidity for yew should be controlled at around 75-85%, so that the yew can grow quickly.
3. Adjusting light
When growing yew, pay attention to adjusting light. Generally, in summer and autumn, about two hours of sun before 10 a.m. or after 5 p.m. each day is enough. Do not leave yew in direct sunlight for too long, as this is not conducive to the growth of yew.
The above is the related introduction to yew cultivation methods compiled by the editor. Have you all learned it? We hope it is helpful to everyone.
The Anti-Cancer Plant Yew
In Yunnan Province, known as the "Plant Kingdom," there grows a plant that appeared about 200 million years ago——yew.Yew, also called Chinese yew and Japanese yew, is a shallow-rooted plant of the Taxaceae family and Taxus genus, and is recognized worldwide as a rare natural plant that is on the verge of extinction. The tree species of this genus gets the name yew because its leaves resemble fir leaves and its fruit is round and bean-shaped with a red aril, just like the "love bean" of the south. There are 11 species (varieties) of Taxus plants in the world, scattered across the continents of the Northern Hemisphere. China has 4 species and 1 variety. During the Jurassic, Cretaceous and early Tertiary periods (190 million to 65 million years ago), plants of this genus were widely distributed in Eurasia and North America. By the Quaternary glacial period, different populations had contracted to their present distribution areas. They are ancient Tertiary relict plants and "living fossils" of the plant world. They have great scientific research value in the study of species origin, evolution, forest succession, forest geography and other aspects.
In the 1970s, researchers discovered that taxol extracted from yew bark and leaves has a unique inhibitory function on tumor cells and can prevent the proliferation of cancer cells. Taxol therefore became the representative of a new generation of anti-cancer drugs and was hailed as "plant gold." Yew also became a "medicinal plant that shocked the world" and one of the hottest subjects of medicinal plant research in the world today.
All 5 species of yew in China can be used to extract taxol. Among them, Yunnan yew has the highest taxol content and stands out among cancer-treating plant resources.
Yunnan Yew
Yunnan yew is an evergreen tree that can reach 30 m in height and 2 m in diameter at breast height. The bark peels off in strips or cracks and sheds in scale-like pieces. The leaves are thin and soft in texture, arranged spirally in two rows, lanceolate-linear to lanceolate, often curved sickle-like, with margins rolled downward or slightly rolled, and both the midrib band and the stomatal band densely covered with evenly minute horny papilla-like protruding points, often the same color as the stomatal band. It is dioecious. Male cones are pale yellow; seeds are ovate, with a small pointed tip at the apex and an oval hilum, born in a fleshy cup-shaped aril. When mature, the aril is red or orange-yellow. Cones open from March to April, and the fruit matures from August to October of the following year.
Yunnan yew is a relict species distributed mainly in Yunnan and Xizang, and also found in Sichuan. It mainly grows scattered or in patches in coniferous forests, mixed coniferous and broad-leaved forests, and evergreen broad-leaved forests on shady and semi-shady slopes at altitudes of 1,650-3,300 m in the Yushajiang, Lancangjiang and Nujiang river basins of western Yunnan, often becoming part of the lower tree layer. It has strict requirements for its growing environment and is greatly limited in geographical distribution. Yunnan's natural resource area is about 200,000 hectares, but the growing stock is only 700,000 cubic meters, with about 3.5 million trees, dominated by near-mature, mature and over-mature forests.
Uses of Yew
Yew has high horticultural ornamental value, with a graceful tree shape, luxuriant branches and leaves, strong sprouting ability and strong disease resistance. It is often cultivated into various shapes such as umbrella-shaped and round. Because it grows slowly, it can maintain a certain shape for a long time after pruning. Especially in autumn and winter, the bright and eye-catching red fruits and emerald green branches and leaves set each other off and are even more striking. At the United Nations headquarters in New York, the White House plaza in the United States and Buckingham Palace in the United Kingdom, yew is used as a hedge or landscape tree species.
Yew is also a precious timber. The wood is reddish-brown to purplish-red, with a strong luster, fragrance, straight grain, fine structure, strong rot resistance, fast drying and little warping or cracking. It is most suitable for making decorations, carvings and arts and crafts. The seed oil content of yew is 29.9%, and the oil can be refined into lubricating oil.
Taxol and Yew
Yew is a traditional Chinese medicinal material used to expel parasites, reduce food stagnation, promote urination, promote menstruation, reduce inflammation, remove toxins and treat various intestinal parasitic diseases. The famous medical work "Compendium of Materia Medica" first recorded that yew can treat cholera and typhoid and remove toxins. Yew contains a certain amount of tannins, which have antibacterial, astringent, anti-inflammatory and detoxifying effects. It not only has a therapeutic effect on upper respiratory tract inflammation, but also has significant effects on gastritis, enteritis, oral ulcers, diabetes, gonorrhea, rheumatoid diseases and so on. For external use, it can treat hemorrhoids, dermatitis, athlete's foot and so on.
However, yew is extremely toxic. Long-term large consumption will inhibit the hematopoietic function of bone marrow, leading to a decrease in white blood cells, and in severe cases can cause bradycardia, cardiac arrest and even death. Therefore, in 2006, China's Ministry of Health issued an announcement strictly prohibiting food production and business units from producing and selling foods containing yew, and at the same time listed yew in the "List of Prohibited Items for Health Foods."
Modern research and development on the medicinal value of Taxus plants began in 1856, when German scientists extracted taxine from the leaves of European yew. Starting in 1958, research institutions represented by the U.S. National Cancer Institute (NCI) took the lead in carrying out experimental research on screening anti-cancer active substances from plants. The bark of the Pacific yew, as one of 35,000 screened materials, was also sent to NCI. Scientists discovered taxol from extracts of Pacific yew bark and revealed taxol's unique anti-cancer mechanism. In 1992, the U.S. Food and Drug Administration (FDA) officially approved the taxol preparation "Taxol" for marketing in the United States as a treatment drug for various malignant tumors and other diseases. Because of its high cure rate, it caused a sensation. It is still the only plant-based drug that can control the growth of cancer cells.
Since then, market demand for taxol has continued to increase. Global taxol sales have grown at a rate of 20%-30% every year. Treating cancer patients requires the consumption of about 1,500-2,500 kg of taxol each year, while current production is only 500-700 kg. The gap between supply and demand continues to widen, and the price of taxol has risen accordingly. Internationally, 1 gram of taxol sells for as much as 5,000 U.S. dollars, hundreds of times more expensive than gold.
Useful but Not Guilty
Taxus plants grow slowly, and the taxol currently sold is still mainly extracted directly from the natural branches, leaves, bark and roots of yew. However, the taxol content in Taxus plants is very low. For every 1 kg of taxol extracted, 1,000-3,000 trees must be cut down. If we relied only on natural resources to obtain raw materials, even if all natural resources were cut down, it would only meet short-term needs.
In addition, countries such as the United States and Canada have implemented legislative protection for yew plants, so the medicinal source of taxol shifted to China and other countries. Under such circumstances, driven by economic interests, in the early 1990s many merchants at home and abroad rushed to Yunnan and other places to develop and purchase yew, and yew resources in some areas suffered serious damage. Because the bark of yew has the highest taxol content, many yews were tragically stripped of their bark, and the final outcome for yews stripped of bark was death. This made resources that were already generally poor in natural regeneration due to genetic factors (dioecious, few seeds) and strict requirements for growing environment even scarcer, and the preservation of the species was greatly threatened.
To change this situation, since 1992 China has formulated a series of protection measures, designating yew resource-producing areas as nature reserves or natural forest protection projects and strictly prohibiting logging. At the same time, large-scale and intensive afforestation projects have been carried out. Researchers have also focused on experimental research on the ecology and biological characteristics of Taxus plants, the variation patterns of taxol content, and extraction techniques for different parts, attempting to convert taxol analogs contained in plants of this genus into taxol through certain chemical reactions.
In fact, as early as 1984, some species of Taxus were listed as rare and endangered plants in the "China Plant Red Data Book" issued by the Environmental Protection Committee of the State Council. In 1996, all 5 species of yew in this genus were listed by the State Council as wild plants under national Class I key protection, and at the proposal of the United Nations, 152 sovereign countries including China jointly signed the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Among the protected plants listed in the appendices of the convention for which global commercial trade is prohibited is yew.
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Close Relatives of Yunnan Yew in China
Southern yew: leaves are relatively wide and long, lanceolate-linear, often sickle-shaped, 2-45 cm long and 3-5 mm wide, thick in texture, with the midrib band and stomatal band on the underside different in color, without horny papillae, or with one to several rows of horny papillae near the stomatal band, and margins revolute. Seeds are slightly flattened and obovate.
Southern yew is the most widely distributed species of Taxus in China, found in more than a dozen provinces and regions south of Henan, Shaanxi, Gansu and Shanxi, scattered in mountain forests below 1,200 m in altitude. Many ancient southern yew trees still have luxuriant branches and leaves, and some (female trees) are heavily loaded with fruit. A southern yew in Yuyan Town, Songyang County, Zhejiang Province, is 30 m tall with a diameter at breast height of 278 cm. The hollow at the base of the trunk is more than 2 m in diameter and can hold an eight-immortals table for 8 people to sit around and enjoy themselves. The tree is more than a thousand years old and is the largest single plant of the Taxus genus in China.
Chinese yew: leaves are slightly thicker in texture, with margins not rolled or slightly rolled, leaves relatively short, linear, slightly sickle-shaped or relatively straight, usually 1.5-2.2 cm long and 2-3 mm wide, with the midrib band on the underside densely covered with evenly minute round horny papilla-like protruding points, whose color is often the same as the stomatal band, and seeds mostly ovate or obovate. It is produced in Gansu, Shaanxi, Sichuan, Yunnan, Guizhou, Sichuan, Hubei, Hunan, Guangxi, Anhui and other provinces (regions), on mountains at altitudes of 1,000-1,200 m.
Northeastern yew: leaves are arranged in irregular two rows, relatively dense, often spreading in a "V" shape, linear, with no horny papilla-like protruding points on the midrib band on the underside, and seeds ovate or triangular-ovate, usually with 3-4 blunt ridges on the upper part, and the hilum triangular or quadrangular. It is produced in the Laoyeling, Zhangguangcailing and Changbai Mountain areas south of the Heilongjiang and Songhua River basins at altitudes of 500-1,000 m.
The Miraculous Anti-Cancer Plant Yew
Yew is the general name for plants of the Taxus genus. There are about 11 species in this genus, distributed in the Northern Hemisphere. China has 4 species and 1 variety.
Yew is a shallow-rooted plant, with an inconspicuous main root and well-developed lateral roots. It is recognized worldwide as a rare natural anti-cancer plant on the verge of extinction. It is an ancient relict tree species left over from the Quaternary glacial period and has a history of 2.5 million years on Earth. Because yew grows slowly under natural conditions and has poor regeneration ability, for a long time no large-scale yew raw material forest base has been formed anywhere in the world.
At the beginning of the 20th century, there was a yew forest in the mountains of the western United States. In the mountain forest was a small village with more than 2,000 residents. Although this small village was not large, it was famous in the United States for longevity. The shortest-lived people in the village lived to be over 95 years old, and the vast majority lived to be over 100. Centenarians could be seen everywhere! This news attracted the attention of many scientists, who came one after another to investigate. However, they did not find anything unusual about the people there, whose diet and lifestyle were not very different from those of people in other regions. After careful observation, they found that the residents here had two living habits related to yew: first, they liked to pick yew leaves and brew them as tea; second, they often walked or exercised in the yew forest.This phenomenon aroused great interest among scientists. Through their unremitting efforts, in 1992 the American company Bristol-Myers Squibb extracted the natural anti-cancer substance taxol from yew. Subsequently, researchers in the United Kingdom, Russia, South Korea and China also extracted this precious drug from it. Taxol has a unique anti-tumor effect and can significantly inhibit tumor growth, with definite efficacy against advanced ovarian cancer, breast cancer, non-small cell lung cancer, Kaposi's sarcoma and so on, and with very few side effects. When countries around the world were anxious about being unable to conquer cancer, the discovery of taxol in yew was like a life-saving magical mushroom, bringing hope of life to cancer patients. Experts and scholars believe that yew is the anti-cancer drug with the greatest development prospects this century and is also one of the most effective anti-cancer drugs recognized worldwide. Taxol sells for a high price, up to 8 million-11 million U.S. dollars per kg on the international market, showing just how precious it is!
Every part of the yew is valuable. The bark, trunk, leaves, roots and seeds are all very important Chinese medicinal materials. Its bark is sweet and sour and can be used as a raw material for beverages, the seeds can be pressed for oil, and the leaves can be used as tea. These things not only have health-care effects, but also have significant effects on promoting menstruation, promoting urination, lowering blood pressure, and treating diabetes and cardiovascular and cerebrovascular diseases.
With the continuous development of science and technology, new uses of taxol are also being discovered. According to a report in the magazine "European Doctor," taxol has a good therapeutic effect on a variety of chronic stubborn diseases, such as progressive sclerosis, rheumatoid arthritis, psoriasis, eczema and so on, with good treatment results. As time goes on, the uses of taxol will be further recognized by people, and its scope of therapeutic application will also expand.
Since yew has such miraculous effects, it should in theory be developed on a large scale and in large quantities. However, what is not optimistic is that the world's annual output of taxol is below 300 kg, because yew is a rare and endangered plant, an ancient tree species left over from the Tertiary glacial period, with a history of 2.5 million years, and is very rare in the world. Its growth rate is also very slow. A mature tree with a diameter at breast height of about 50 cm needs more than a hundred years to grow, and the tree can live for more than a thousand years. Yew is an evergreen tree with great ornamental value, but its own reproductive capacity is extremely poor, and new trees cannot keep up with natural death. Artificial asexual propagation (cuttings, etc.) has a rooting rate of only 17%. It is understood that there are currently about 10 species of yew in the world, and 5 species within China, including Qinghai-Xizang Plateau yew, Yunnan-Guizhou Plateau yew, southern yew, northeastern yew, northwestern yew and so on. Because the resource quantity is very small while the medicinal value is huge, human destruction has been severe, and many places have fallen into a state of near extinction. China Central Television once exposed the farce of reckless yew logging in Yunnan: a large area of yew forest was discovered in Yunnan's primeval forest, and its taxol content was more than double that of other varieties. Some lawbreakers colluded with foreign merchants to purchase yew branches, leaves, bark and roots at a price of 1 yuan per kg. In just a few months, tens of thousands of yews were stripped of bark, dug up by the roots and cut down to the point of exhaustion. In this catastrophe, more than 92,000 yews were cut down in the Yunlong Nature Reserve alone, with direct economic losses of 1-1.3 billion U.S. dollars, becoming an unprecedented disaster for yew. It is understood that yews in other areas also suffered damage to varying degrees, and even the yews in the mixed coniferous and broad-leaved forests in the transition zone from the eastern Qinghai-Xizang Plateau to the Qinba Mountains were damaged.
The painful lesson awakened people. In August 1999, the State Council approved the "List of National Key Protected Wild Plants (First Batch)," listing yew as a national first-class protected plant. All yew distribution areas have formulated protection plans, combining development and utilization with protection, carrying out rational harvesting, and strengthening protection of the tree species. Scientific workers in Yunnan, Heilongjiang, Gansu and other places, based on the characteristics of yew such as preferring shade, not being choosy about soil, tolerating cold and barren conditions, having well-developed root systems, and being able to be planted mixed with other tree species, began artificial cultivation and breeding to expand the number of yew trees and meet the pharmaceutical industry's demand for raw materials. It can be expected that the era is coming when yew, this miraculous "national treasure"-level plant, will make even greater contributions to humanity.