Written by Maggie
Mar 01 2021
Dawn Redwood (Metasequoia glyptostroboides Hu & W. C. Cheng): Gymnospermatic cypressaceae. Dawn Redwood is a deciduous tree, branchlets opposite, pendulous. Leaves are linear, alternating opposite, pseudodiallel into pinnately compound leaves, 1-1.7 cm long, with 4-8 stomatal lines on the lower sides.Hermaphrodite.Cones pendulous, subglobose, micronucleated, 1.8-2.5 cm long, long stalk; Species scales woody, peltate, each with 5 to 9 seeds, the seeds flattened, surrounded by narrow wings.
There were about 6 ~ 7 species of Dawn Redwood in the Cretaceous and Cenozoic of Mesozoic, which was thought to be extinct long ago. In 1941, Chinese botanists first discovered this rare and ancient tree species in Moudao Town, Lichuan, Hubei Province (then Modaoxi, Wan County, Sichuan Province). According to recent investigations, giant trees of more than 300 years have been found in Wanzhou, Shizhu County, Chongqing, Lichuan, Hubei and Longshan, Hunan. Dawn Redwood has strong adaptability, likes wet and fast growth, and can be grown all over the south of Beijing. The material is light and soft, which can be used for construction, sheet material, paper making, etc. Dawn Redwood is a graceful, ornamental tree for the garden.
Dawn Redwood is a tree with a height of 35 m and a diameter at breast height of 2.5 m; Trunk base often enlarged; Bark is gray, grayish-brown or dark gray, saplings split into flakes off, trees split into strips off, endothelium light purple-brown; Branches of dawn redwood are oblique exhibition, twigs droop, young tree crown pinnacle shape, old tree crown wide round, branches and leaves sparse; Annual branches are smooth glabrous, green when young, then gradually become light brown, two or three years of branches light brown or brown-gray; Lateral branchlets are pinnate, 4-15 cm long, winter litter; Winter buds on main branches ovoid or elliptic, apically obtuse, ca. 4 mm long and 3 mm in diameter, bud scales broadly ovate, apically rounded or obtuse, nearly equal in length and width, ca. 2-2.5 mm, margin thin and pale, dorsal with longitudinal ridges. Leaves of dawn redwood are striped, 0.8-3.5 (often 1.3-2) cm long, 1-2.5 (often 1.5-2) mm wide, pale green above, paler underside, with two yellowish stomatal bands slightly wider along the midvein, each with 4-8 stomatal lines, leaves in two rows on lateral branchlets, pinnate, falling off with the branch in winter.
Cones of dawn redwood are pendulous, nearly tetragonal globose or rectangular globose, green before maturity, dark brown when ripe, 1.8-2.5 cm long, 1.6-2.5 cm in diameter, peduncles 2-4 cm long, on which there are cross opposite strip leaves; Seed scales woody, estate, usually 11-12 pairs, crossed opposite, scales apically oblate rhomboid, with a transverse groove in the center, base cuneate, 7-9 mm high, breeding scales with 5-9 seeds; Seeds of dawn redwood are flattened, obovate, sometimes orbicular or almost orbicular, surrounded by wings, apically indented, ca. 5 mm long, 4 mm diameter; dawn redwood has 2 cotyledons, striped, 1.1-1.3 cm long, 1.5-2 mm wide, midveins slightly raised on both sides, stomatal lines above, no stomatal lines below; Primary leaves are striate, cross opposite, 1-1.8 cm long, with stomatal lines below.
Dawn redwood likes warm and humid climate, cool in summer, snow in winter but not cold, and the annual average temperature of producing area is 13℃, extreme lowest temperature -8℃, extreme highest temperature 24℃, frost-free period 230 days; The annual precipitation is 1500 mm, and the annual average relative humidity is 82%. The soil is acidic montane yellow soil, purple soil or alluvial soil with a pH value of 4.5~5.5.
In valleys or near the foothills gently topography, soil deep, wet, or a little water, strong cold resistance, resistance to water wet ability strong, saline-alkali land in light optical trees can grow as xi, root development, growth speed is often dominated by soil moisture, in the long-term water drainage of slow growth, stem base) and usually has a longitudinal rib. Dawn redwood is light-loving, poor and drought - tolerant, air - purifying, slow-growing, easy to transplant. The suitable temperature is 8 ~24 degrees below zero.
Dawn redwood distributes in Hubei, Chongqing, Hunan border of Lichuan, Shizhu, Longshan County in local areas, vertical distribution is generally 750~1500 meters above sea level.
After the cones of dawn redwood are mature, the seeds are picked and insolated, and the seeds are screened and dried. The sowing amount of acre is 0.75~1.5kg, the use of drill sowing (row spacing 20~25cm) or broadcast, after sowing grass should not be too thick, often keep the soil moist.
Hard and tender cuttings can be used.
It takes place in spring. Semi-lignified shoots of dawn redwood were selected as cuttings, 14~18cm in length, with 4~5 leaves at the top and upper parts retained, and inserted into the soil 4~6cm, with 70,000 ~ 80,000 plants per mu. After shading, spray 3~5 times a day. The shade can be removed after autumn. Nursery often keeps moist ventilation, which can promote cuttings early root. Attention should be paid to the prevention and control of blight and stem rot at the seedling stage.
The planting season can be from late autumn to early spring. Generally, the dawn redwood is better to plant in late winter. Don't plant dawn redwood in the cold season and growing season (summer) when the soil is frozen, otherwise the survival rate is very low. The seedling should be planted along with the rise to avoid excessive water loss. If after a long-distance transportation, after arriving at the destination, should be immersed in water roots. Large seedling transplanting must take soil ball, dig a hole, apply sufficient base fertilizer, fill in fine soil after stepping on solid, after planting to pour permeable water. Extravagant growth period to top dressing, generally chase 1 time, pay attention to soil, weeding.
Weeing and loosening the soil means to remove weeds and vines, loosen the soil to enhance air permeability, improve physical and chemical properties, create comfortable and good soil environment space, improve the root life function, promote its robust and rapid growth, and lay a solid foundation for Dawn Redwood's high yield and high efficiency. Weed the grass and loosened the soil twice a year, and the best effect was obtained in the early stage of Dawn Redwood's vigorous growth.
In order to make full use of the forest open space, improve the land utilization rate, improve the soil structure, and enhance soil fertility, legume crops or green manure can be interplanted appropriately within 1~2 years of afforestation. In order not to affect the growth of dawn redwood seedlings, interplanting crops should keep a distance of 30~40cm from the tree seedlings. Through the crop in tillage weeding Yao fertilization, already can have the effect that with tillage generation caress, can increase income again, achieve with short raise long goal.
In order to maintain ventilation and light, and create a good space for the robust growth of dawn redwood, moderate pruning should be carried out after the forest is formed. It is advisable to prune from the day after Dawn Redwood leaves to the day before the beginning of spring. The intensity of pruning should be 1/4 to 1/3 of the total length of the crown, depending on the growth of trees.
1 to 2 generations occur in a year, with the young moth into the stem harm, causing branches dead, the plant can not grow and bloom normally, or stem cavities and break off.
Rosa japonicus can occur in two generations every year, overwintering with larvae cocooning in the soil. There is a flocking habit, often dozens of head flocking on the leaves for food, serious when the leaves can be eaten up, leaving only thick veins. Female insect lays eggs in the shoot, can cause the shoot to die.
It can occur 5 to 6 generations a year, and overwinters as adults in evergreen trees such as Platycladus platycladus or weeds. Nymphs or adult worms use the mouth to prick suction juice, make leaf appears pale white spot, the spot shows patch shape when harm is serious, or prick epidermis, make branch leaf wither.
Symptoms: Fungal disease. Mainly damage leaves and buds of dawn redwood. In spring, the disease begins after leaf expansion. Yellow rust spores are produced on the leaf back, petiole and vein. After breaking through the epidermis, orange rust spores come out and invade the plant. To the early summer, a large number of spread, the formation of orange or yellow-brown powdery summer spore pile, make the leaves lose green-yellow, disease spots obviously raised, serious, the whole plant leaves dead, or dried off the bud.
Pathogenesis characteristics: the pathogen with mycelium or winter spores in the disease bud, disease branch overwintering, spores with the help of wind and rain transmission, invasion by stomata, in the growth season can be repeated infection. Areas with four warm seasons are severely affected, while areas with cold winter and high summer temperatures are less affected.
Dawn Redwood sapwood is white, heartwood is brown, the material is light and soft, the texture is straight, the structure is slightly coarse, the hardness difference between morning and evening is big, not resistant to water and wet. dawn redwood can be used for construction, sheet material, paper making, appliance making, model making and interior decoration.
Dawn Redwood is a "living fossil" tree and an ornamental tree with autumn leaves. In the Garden most suitable for planting, dawn redwood can also be planted, planting, and can be used for embankment, lakeside, poolside, courtyard and another greening, can also be potted. dawn redwood can also be planted to create landscape forest, and suitable for evergreen ground cover plants; dawn redwood can also be planted in front of buildings or used as a street tree. Dawn Redwood has a certain resistance to sulfur dioxide and is an excellent tree for industrial and mining areas.