Characteristics and uses of boxwood in Hokkaido

Hokkaido boxwood is a new variety of Euonymus introduced by the Chinese Academy of Forestry Sciences in the mid-1980s. It is an evergreen broad-leaved tree of the genus Euonymus and a cultivated variety of Euonymus. It has the characteristics of tall tree body, tall and straight tree posture, evergreen in four seasons, considerable red fruit in winter and so on. As the new rural construction is gradually put on the agenda, greening and beautifying the environment will become an important part of the new rural construction. In order to change the single mode of deciduous trees in temperate zone and develop to high-grade greening and beautification, more and more evergreen tree species without environmental pollution have been paid more and more attention. Practice has proved that Hokkaido boxwood is a rare tree species for greening and beautification.

1. Morphological characteristics

Hokkaido boxwood is an evergreen tree with leathery leaves, dark green on the front and light green on the back, with green leaves and no fallen leaves in the cold winter. The leaves are ovate or long oval, 5 cm long and 4 cm wide, the leaf margin is shallow wavy, and the petiole is about 1 cm long. The flower is light yellow, the diameter is 0.1cm, the capsule is nearly spherical, there are 4 shallow grooves, the diameter is 1cm, the fruit is light green when the fruit is tender, the sunny side is brown red, the seed is nearly spherical, it matures in November, the pericarp cracks automatically when it is mature, the seed that orange red chases the seed coat is exposed, full of red fruit and green leaves, far and close view, quite interesting, pleasant scenery.

II. Biological characteristics

Hokkaido yellow poplar is light-loving, shade-tolerant, warm and humid, cold-resistant and drought-resistant, and can remain green when the lowest temperature is-23.9 ℃. The highest annual height growth is 170 cm, the average growth is about 70 cm, the growth rate is 3 to 5 times faster than that of ordinary Euonymus tomentosa, the height of 5-year-old seedlings can reach more than 3 meters, and the 3-year-old seedlings can reach 3.5 meters with a ground diameter of more than 3 centimeters. The growth of seedlings in the first three or four years is particularly obvious, with less lateral branches, sturdy tip, obvious tip dominance, single stem straight up, showing excellent tree characters. It entered the early fruiting stage after 5 years, and entered the fruiting peak period in 6 ~ 8 years. It was easy to propagate, the survival rate of branch cuttings was high, and it could propagate rapidly and in large numbers.

Third, strong resistance

Hokkaido boxwood has strong resistance to powdery mildew and black spot. After years of domestication, breeding and optimization, it has become an excellent new variety suitable for the climatic conditions in northern China. Its drought tolerance is also better than that of Populus tomentosa; it has a strong ability to absorb harmful gases and has strong resistance to harmful gases such as sulfur dioxide, hydrogen, hydrogen fluoride and so on.

IV. Suitable range of growth

It is suitable for planting in cold and arid areas of northern China in winter. it can be planted alone, arranged or group in urban courtyard greening. In the north, it can blossom and bear fruit normally, and the seeds have germinating power, so it can breed offspring.

Fifth, present new products

Since Hokkaido boxwood was introduced into China for more than 20 years, two new varieties of Hokkaido boxwood have been selected and bred, which are worth using in production.

1. Donghong Hokkaido boxwood

Evergreen shrubs or small trees. The leaves are bright leathery, dark green in spring, summer and autumn, bright red in branches and leaves in winter, and twice as much fruit as common varieties. It has strong ornamental and cold resistance, so it is suitable for greening in northern cities.

2. Colored leaves Hokkaido boxwood

Evergreen shrubs or small trees. The leaves are golden and green all the year round, with strong upright and cold resistance. Full of red fruits in winter, can be used as hedges or pruning shapes.

VI. Current situation of Greening

The north of the Huaihe River is located in the warm temperate zone, dry and cold in winter and spring, strong wind, leaves withered, cold-resistant, drought-tolerant evergreen trees are few. At present, there are only Platycladus orientalis, Privet, Photinia vulgaris, Ligustrum lucidum and other evergreen coniferous broad-leaved trees introduced in recent years, such as sweet-scented osmanthus, Magnolia, camphor, Michelia, Duying, palm, hook bone and other evergreen coniferous broad-leaved trees, some of which are subtropical and have been planted to the north of the Huaihe River for a short time, not because they can survive the winter in the current few years, even if they are successfully introduced. For example, magnolia, camphor, hook bone and Michelia mollissima have varying degrees of yellowing, ruining the scenery. Most of the inherent evergreen trees are shrubs, and only cypresses are trees, but because of their slow growth and dark and monotonous leaves in winter, it is difficult to meet the needs of people's vision, landscape and the construction of a new countryside.

VII. a wide range of uses

Hokkaido boxwood crown is beautiful green, after autumn, it is full of mature fruit, showing red aril, clusters of red fruit embedded in green leaves, even in the cold and dry winter, the whole crown is still beautiful green, green leaves and red fruit, ornamental value is extremely high. The poplar of Hokkaido is tall and straight, evergreen all the year round and resistant to pruning and shaping. It is an excellent variety of landscaping in small towns and urban construction in northern China. Because of its shade tolerance, it can be used to build road mixed forest.

VIII. Development prospects

In order to increase the adaptability and appreciation of Hokkaido boxwood, it has recently been grafted onto silk cotton wood native to the north by horticulturists, and it has been successful. Now, more wild silk cotton trees in rural areas can be used as rootstocks to graft Hokkaido yellow poplar, Donghong Hokkaido yellow poplar, color leaf Hokkaido yellow poplar, gold leaf holly spear, colored leaf cotton or color leaf trees of the family Celastraceae, such as Jinxin, Phnom Penh, etc. to form a unique landscape. On the basis of increasing seedling reproduction, Hokkaido boxwood and its similar species walk out of cities, market towns, gardens, streets, parks and courtyards, and often flash on roads, riverbanks, fields and fields to build a colorful living environment.