por What is the kiri tree?
He kiri tree (paulownia tomentosa) It is native to China and has been cultivated in East Asia for over 3,000 years. The species is considered to bring good luck and the phoenix bird only perches on its branches.
This tree can reach 20 meters and has showy, light purple flowers. The seeds are very small and winged. More than 2,000 seeds can be present in a fruit, dispersed by the wind.
The species is naturally distributed in western and central China, but is cultivated throughout the world, mainly as an ornamental. It naturally grows in open forests, since it requires a large amount of light for its development.
In the first year of life the growth of the plant is slow, but later it accelerates. The species can grow up to two meters each year, until reaching maturity, and can live for 60 to 70 years.
The kiri tree has been used for thousands of years in traditional Chinese medicine. Almost all parts of the plant have medicinal use, mainly for their antimicrobial activity. Its potential use in the treatment of some types of cancer, as well as various respiratory diseases, has also been verified.
Characteristics of the kiri tree
The kiri tree (paulownia tomentosa) is also known as the empress tree, princess tree, or imperial tree. It is cultivated in China mainly as an ornamental and for its medicinal properties.
According to ancient Chinese legends, the phoenix only perches on the branches of this tree. It was customary among these settlers to plant kiri trees around their houses to attract good luck and the phoenix.
Tree 8 to 12 m tall, which in some cases reaches 20 m. It is deciduous (it loses its leaves at one time of the year) with a fairly extended crown.
The trunk can measure 30 to 40 cm in diameter, greyish in color. The bark is thin, rough and cracked in appearance.
The root system is quite widespread and deep, with support roots up to 8 m long. The absorption roots can be up to 60 cm in length.
The leaves are simple, opposite and ovate. Its size ranges from 12 to 30 cm long by 15 to 30 cm wide. The margin of the leaf blade is entire, the apex acute, and the base cordate (heart-shaped). The consistency is cartaceous (similar to cardboard) and pubescent (with hairs) both on the upper side and on the underside.
The inflorescences are cymose (indeterminate), terminal, 20-50 cm long. The flowers are hermaphroditic, pentamerous (with five pieces per floral whorl).
The calyx is fleshy, pubescent, bell-shaped. The corolla is tubular, bilabiate, and light purple in color, with the tube 5-6 cm long.
The fruit is an ovoid loculicidal capsule with a woody consistency. The capsule is 2.5 to 5 cm long, dark brown when mature, and remains on the plant during the winter. The seeds are numerous, several winged, 2.5-4 mm long.
The species was described by Carl Thunberg in 1784 under the name of bignonia tomentosa, being located in the Bignoniaceae family. Later, in 1841, Ernst von Steudel placed it in the genus paulownia.
The gender paulownia it was proposed in 1835 by Siebold and Zuccarini in a publication of the Flora of Japan. paulownia it was transferred to the family Schrophulariaceae and later separated to the family Paulowniaceae. This family was proposed by the Japanese Nakai in 1949, with a single genus (paulownia).
Name paulownia It was dedicated to Duchess Anna Pavlovna of Russia, who was the daughter of Tsar Paul I. The specific epithet stormy refers to the pubescence that the leaves of this species present.
For P. tomentosa Two varieties are recognized. Variety stormy It is the most common and is characterized by abundant pubescence on the underside of the leaf. Variety tsinlingensis It was described in 1976 by Gong Tong and is glabrous (without trichomes) or with few trichomes on the underside of the leaf.
No special preparation of the land is required for the cultivation of the species. It is convenient to moisten the soil before planting to facilitate the work in the field.
paulownia tomentosa it is tolerant of different soil conditions, but is very sensitive to drainage problems. The best soils for its cultivation are sandy or rich in peat that do not present water retention problems, and the ideal pH is between 5 and 8.
The species can grow in saline or nutrient-poor soils, due to its great capacity to selectively absorb Ca and Mg ions.
The recommended planting density is 400 to 500 plants per hectare. Planting should be done in holes 70 to 80 cm long by 50 to 60 cm wide. Irrigation should be done twice the day of planting and then seven to eight days later.
To guarantee a good development of the main trunk, pruning should be carried out from the third or fourth year of cultivation.
Habitat and distribution
The species is native to western and central China. It is widely cultivated as an ornamental plant on all continents except Antarctica.
In its natural habitat, P. tomentosa It grows preferentially in humid or semi-dry open forests below 1,800 m of altitude.
The average annual temperature in its natural distribution area ranges from 11 to 17 °C. However, they can tolerate extreme temperatures from -20 to 40 °C. The average annual precipitation in its area of origin is in a range between 500 and 1,500 mm, with 3 to 9 dry months.
The species does not tolerate shade. It requires large amounts of light for rapid development and prefers alkaline soils.
Growth
Seedling establishment may be poor under natural conditions. Survival increases in tilled soils (68%), compared to uncultivated soils (40%). Also, a large amount of light is required to promote seedling growth.
Growth is slow during the first year, due to the further development of the root system. In a study carried out in the field in 2003, it was found that during the first three years of the plant’s life the root system increases by 200%.
Later, growth accelerates and plants can increase in height by 2 m and trunk diameter by 3-4 cm per year. The maturity of the plants (reproductive state) can be reached in the fourth or fifth year, in favorable environmental conditions, and in cultivated plants it can be at three years. In its natural range, reproductive status can be reached at eight years of age.
Flowering occurs between April and May, and the fruits are formed between August and September. The capsules mature for several months and open in the spring when the seeds are dispersed. The trees are considered short-lived, since they only live between 60 and 70 years.
Seeds
the seeds of P. tomentosa they are very small (2.5 to 4 mm wide) and weigh approximately 0.17 mg. They are oval in shape, with a reticulate surface and striated membranous wings.
Approximately 2,000 seeds are present in a capsule and a tree can produce more than 20 million seeds a year. When the fruit ripens and opens, the seeds are dispersed by the wind at distances that can reach 3 km from the mother plant.
The moisture content of the seeds is approximately 7% and they can survive in the soil seed bank for at least two to three years. The germination percentage reaches 90% in the first days after dispersal and subsequently decreases.
Seeds may present secondary dormancy (a state that prevents them from germinating) if they are subjected to unfavorable environmental conditions. Low temperatures, sudden changes in humidity, and darkness can promote this dormancy.
The light needs of the seeds to germinate are much higher than in other species. In laboratory studies, light ranges to stimulate germination from minutes to hours, depending on seed age and storage conditions.
Health properties
The species has been used as a medicinal plant in traditional Chinese medicine. Already in 1578 Li Shizhen, in Compendium of Materia Medicaindicates that the bark of paulownia It is used to treat hemorrhoids and against parasites. It also indicates that the flowers are anti-inflammatory and help hair growth.
In traditional medicine the uses that are currently given are very broad. Both the bark of the plant and leaves, flowers and fruits are used. Among other conditions, bronchitis, gonorrhea, mumps, asthma, diarrhea, conjunctivitis, hypertension and tonsillitis are treated.
Based on these uses, scientific research has been carried out to study the chemical compounds present in P. tomentosa. Likewise, some tests have been carried out to verify its effect in the treatment of various diseases.
The different parts of the plant, due to the different compounds they have, are used to treat various diseases.
Leaves
Flavonoids have been isolated from the leaves and have shown effects against free radical damage to cells. In addition, they produce a hydrocarbon of the type of terpenes (isoatricolide tiglata) with a potential carcinogenic effect and neuronal protection.
This terpene has been shown to cause apoptosis (programmed cell death) in cervical and lung cancer cells. On the other hand, extracts from the leaves have shown positive effects against glutamate toxicity in neuronal tissues.
Flowers
The flowers have been widely used in traditional medicine. For the treatment of acne, a flower puree is prepared and applied directly to the condition.
Likewise, a decoction of flowers is prepared to treat mycosis (fungal infection) of the foot and in the treatment of empirosis.
Scientific investigations have shown the presence of numerous flavonoids in flowers. Among these, apigenin has been shown to have hypotensive, antioxidant, anti-inflammatory, and vasorelaxing effects.
Apigenin has also shown effects against tumors in both clinical trials in vitro as live. This flavonoid inhibits the proliferation of tumor-forming cells and stops their invasion.
On the other hand, the extracts obtained from the flowers of P. tomentosa inhibit the growth of some bacteria. The strongest effects have been found against the proliferation of Staphylococcus aureus.
From the dried flowers, a methanol extract is obtained that has potential antiviral activity against enterovirus 71 and coxsackie virus A16. These two viruses are the main pathogens that cause diseases of the hands, feet and mouth.
Also, the essential oils present in the flowers of P. tomentosa showed significant antimicrobial activity in the presence of strains of Bacillus subtilis, Staphylococcus aureus and Escherichia coli.
Finally, it has been found that the flavonoids present in the flowers can reduce inflammation of the trachea and bronchi due to asthma.
fruits and seeds
The fruits of this species have been found to be a natural source of antioxidants. Besides,…