Contents
Scotch pine is the second most common coniferous crop in the world, second only to Scots Juniper. It is often called European, but special editions emphasize that this is wrong. The range of Scotch Pine is extensive, and covers Eurasia from the Arctic almost to the tropics.
Description of Scots pine
Scotch pine (Pinus Sylvestris) is a single-stemmed coniferous tree belonging to the genus Pine (Pinus) of the Pine family (Pinaceae). It is of great importance as a forest-forming species; it is planted where it is necessary to stop soil erosion. This is a valuable ornamental crop, variable, easy to select.
The first detailed description was given by Carl Linnaeus in 1753.
What does Scotch pine look like
The appearance of Scotch pine changes with age. In youth, its crown is cone-shaped to broadly oval, then it becomes like an umbrella. The culture grows very quickly, adding 30 cm or more per year. By the age of 10, the height of Scotch pine is about 4 m.
Mature trees, as a rule, reach 25-40 m. The size of Scots pine depends on the region. For example, the tallest specimens, over 46 m, are most often found on the southern coast of the Baltic Sea.
The trunk of the Scotch pine reaches 50-120 cm in girth. Under ideal conditions, it is straight, but curved specimens are often found in nature. This is due to the damage to the culture by the bud shooter (Evetria turionana), which in Scots pine plants causes deformation of the main conductor, making it knotty.
The bark on young shoots is orange, flaky, becoming reddish-rusty with age. The trunk is gray-brown, covered with deep cracks. On the main conductor, the bark forms thick plates of various sizes and shapes. It is she who, processed and sorted into fractions, is sold in garden centers as mulch.
Young shoots are green, but by the end of the season they turn gray, and in the second spring they turn brown. The branches are at first rhythmically arranged, whorled, in mature pines they are uneven.
The crown crowns the top of the tree, sometimes at the bottom of an adult specimen there is a single branch far removed from the trunk. This is due to the fact that the old shoots begin to die off as soon as they overlap with the young ones, and they lose access to light.
The needles are greyish-green, but may be dark green to greyish-blue in color, and sometimes change color to yellowish green in winter. Rigid needles are slightly curved, collected in 2 pieces, reach a length of 4-7 cm, a width of 2 mm. They have a serrated edge and well-marked stomatal lines. Needles live 2-4 years. In the subarctic regions, it can last up to 9 years.
It is noteworthy that on young, vigorously growing specimens, the needles can be almost 2 times longer, and occasionally grouped in 3-4 pieces. Seedlings have single needles up to a year.
All species belonging to the genus Pine are monoecious. That is, male and female flowers open on the same plant. The Scots pine cycle is 20 months, that is how much time passes between pollination in April-May and the ripening of cones in winter.
They grow singly, rarely collected in 2-3 pieces, have a grayish-brown color and a matte surface. The shape of Scots pine cones is elongated-ovoid with a pointed tip, up to 7,5 cm long. They ripen in late autumn or early winter, open next spring, drop small (4-5 mm) black seeds, and soon fall off.
The root of the culture is pivotal, powerful, goes deep into the ground. Species trees live 150-350 years, but 700-year-old specimens have been registered in Sweden and Norway.
Signs of the species of Scots pine
If we summarize the features of Scotch Pine as a species, the following features should be distinguished:
- The culture is a light-loving plant, resistant to frost and drought, forming a powerful vertical root. It goes deep into the ground and makes the Scotch Pine one of the main forest-forming species in Europe and North Asia, up to the Amur region.
- Species trees have a straight high trunk, which is bent due to damage by a specific pest – silkworm bud shoots.
- The crown of Scotch Pine most often has an uneven umbrella shape, located at the top of the main shoot. The rest of the trunk is left bare as the lower branches die off as the tree grows.
- The old bark peels off in thick plates of various shapes and sizes.
- The needles are collected in 2 pieces, grayish-green.
- The culture is considered frost-resistant, depending on the variety, which will be discussed below, winters in 1-4 zones.
- Trees of this species are among the fastest growing, adding 30 cm or more annually under favorable conditions.
Where does Scots pine grow?
Quite often, Scots Pine is called European. But it grows on a vast territory stretched between Eastern Siberia, Portugal, the Caucasus and the Arctic Circle, Mongolia, Turkey. The Scots Pine is naturalized in Canada where it thrives.
In nature, the culture forms pure pine forests, but can grow together with oak, birch, aspen, and spruce. Depending on subspecies and form, Scotch pine grows from 0 to 2600 m above sea level.
Scotch pine species
Since the range of Scots Pine is extensive, within the species there are about 100 subspecies, forms, ecotypes characteristic of a particular area (not to be confused with varieties). But they are of interest only to biologists. In appearance, the variations of Scotch Pine do not differ too much from each other. The difference is revealed only by genetic analysis or the study of the composition of the resin. It is unlikely that this is of interest to amateur gardeners.
Three broad variations are used in culture:
- Pinus sylvestris var. Hamata or All of them. The most thermophilic, winters in zone 6, grows in the Balkans, the Caucasus, the Crimea, Turkey. It climbs to a height of up to 2600 m. It differs from other varieties in the chemical composition of the resin. The needles do not fade in winter, rather green with a bluish rather than gray tint.
- Pinus sylvestris var. Mongolian or Mongolia. It grows in Siberia, Transbaikalia, Mongolia and northwestern regions of China at an altitude of up to 2 thousand m. It is distinguished by dull long (up to 12 cm) needles, which tend to become yellowish by winter.
- Pinus sylvestris var. Lapland or Лapponika. It is from this subspecies that most European varieties are derived. The main part of the range falls on Europe and extends to Central Siberia. Differs in short rigid needles.
Many cultivars have been derived from Scots Pine. They can be very different in appearance. There are columnar, shrub and dwarf varieties, needles are silver-gray, bluish-green, milky-yellowish, yellow.
Some of them are very unusual and very different from the species tree. These varieties are included in the selection.
Scotch pine Fastigata
Pinus sylvestris Fastigiata in culture since 1856. Columnar trees have been found in Finland, Norway and France, brought to the level of a variety by selection. This Scotch pine is distinguished by an even, straight crown with branches directed upwards, pressed against each other.
It grows rapidly, increasing by about 30 cm per season. By the age of 10, it reaches 4 m. For an adult pine, a height of 15 m or more is typical.
The needles are bluish-green, the cones are smaller than those of the original species. Frost resistance zone – 3. Prefers a sunny landing site.
Scotch pine Fastigata requires careful maintenance. With age, it can expose the trunk and branches, become untidy. Its crown must be “corrected”, preventive treatments against pests and diseases must be carried out so that the needles do not fall off ahead of time.
Scotch pine Globoza Virdis
Pinus sylvestris Globosa Viridis – a common variety, known since 1900. Dwarf form with short, thick, stiff branches hanging to the ground. It gives an annual increase of 2,5 to 15 cm. At the age of 10, the height is not more than 1-1,5 m, it can be significantly lower. The size depends on the growing conditions as well as the nursery. Scotch pine is a variable species, and if growers do their own selection, this affects the height of the tree.
At a young age, Scots pine Globoza Virdis forms an almost round, often asymmetrical crown. Becomes pyramidal with age.
Dark green hard needles about 10 cm, can be rounded up to half the length. Takes on a yellowish tinge in winter. At the end of summer, young short needles often appear, covering the cones.
Prefers a sunny position, undemanding to soils. Winters in zone 5.
Scotch pine
Pinus sylvestris Watereri – a dwarf variety that grows slowly and annually adds about 5-10 cm or a little more. Found in 1965 by Anthony Waterer at Knap Hill Nursery.
By the age of 10, it reaches 1-1,2 m. The height of an adult tree, according to some sources, is up to 7,5 m, according to others – 4-5 m. In any case, this is a modest size for Scotch pine.
In youth, the crown is wide-conical, then it becomes rounded due to outward-directed branches and the ends of the shoots raised upwards.
Bluish-gray, thin twisted needles are short – no more than 4 cm. The variety lives for a long time, the first specimen left to collect seeds and grow seedlings of Scotch pine Watereri can still be seen in the Knap Hill nursery. Winters in the fourth zone.
Scotch pine Hillside Creeper
Pinus sylvestris Hillside Creeper – a variety obtained from a dwarf form. Found in 1970 by Lane Ziegenfuss at the Hillside Nursery, Pennsylvania.
A fast-growing variety that adds 20-30 cm per season. But, due to the nature of the distribution of shoots, in width, not height. By the age of 10, Scotch pine rises 30 cm above the soil surface with a crown diameter of 2-3 m. An adult plant captures a much larger area.
The branches are loose and weak, fragile. The needles are dense, gray-green, in a cold climate or at negative temperatures in the south it acquires a yellowish tint. Winters in zone 3, with light cover or sufficient snow cover feels good in the second.
Scotch pine Aurea
Pinus sylvestris Aurea – an old variety, in culture since 1876. It is a squat shrub with a rounded crown. It can independently or with the help of the owners acquire the shape of a vertical oval or a regular cone.
Before planting Aurea Scots pine in the country, it should be remembered that it grows rapidly, adding about 30 cm per season, and will stretch 10-2,5 m by 4 years. This difference is due to the different conditions in which the tree lives, as well as nursery. They tend to reproduce the slowest growing specimens, thereby participating in the selection. And Scotch pine is extremely variable and lends itself well to selection.
The main advantage of the Aurea variety is the color of the needles. The young is yellow-green, and in winter it becomes golden yellow.
Scotch pine Aurea grows well only in full sun. With a lack of light, the color will fade, but this can somehow be overcome. But if the needles begin to crumble, it will take several seasons to restore the decorative effect, but the tree will have to be replanted.
Scotch pine Aurea winters without shelter in zone 3.
Growing conditions for Scotch pine
Planting and caring for Scotch pine is not difficult, but it is unstable to air pollution. Amateur gardeners cannot influence this factor, but they want to get the culture on the site. So, you need to pay more attention to other requirements of Scots pine.
She prefers a sunny open place, even in her youth she does not tolerate light shading. It develops best on sandy soils that are not prone to wetting and compaction, it withstands wind blows well.
What not a single variety of ordinary pine will tolerate, and species trees too, is the close standing of groundwater. A large drainage layer when planting may not be enough. In such areas, pine is planted on a terrace, an embankment is built, or water is drained. Otherwise, culture will have to be abandoned – its root is pivotal, it goes deep.
Planting Scots pine
In spring, Scotch pine is planted in the northern regions. Then the culture has time to take root well before the onset of cold weather, and is able to survive the winter.
In autumn, Scotch pine is planted in warm and hot climates. In our country, the heat often comes suddenly, when the culture has not even begun to take root. The seedling can easily die just because of the high temperature.
Container plants are planted all season long. But in the south in the summer it is better not to carry out the operation.
Preparation of planting material
Pines need to be bought in containers or with an earthen clod lined with burlap. In any case, the root system must be closed.
You can bring Scotch pine from the nearest forest. If the tree dug out without an earthen clod, and was not tied in place with a damp cloth, the root is immediately soaked in a stimulant, for example, root or heteroauxin. There it should be at least 3 hours, and up to the very landing.
It is believed that after digging in the forest, Scotch pine with an open root should be planted within 15 minutes. Of course, this is impossible, but it is worth hurrying. A delay of even 1-2 hours will be fatal for the plant.
Instances grown in containers are watered the day before planting.
Site preparation
A pit for Scotch pine must be prepared no later than 2 weeks before planting. The closer the groundwater approaches the surface, the thicker the drainage layer should be. In any case, less than 20 cm does not make it.
The depth of the planting pit for standard seedlings (not large ones) should be approximately 70 cm, the diameter should be the width of the container or earthen clod, multiplied by 1,5-2. More deepening can be done, less is undesirable.
It is necessary to completely change the land only in saline areas. The mixture is made up of soddy soil, sand, clay. If necessary, add 200-300 g of lime to the planting hole. Starting fertilizer for pine trees is usually not applied.
First, drainage is poured into the bottom of the pit, then the substrate, not reaching the edge of about 15 cm. The free volume is filled with water until it stops being absorbed.
Rules of landing
Scotch pine is planted no earlier than 2 weeks after the preparation of the pit. It is done in the following sequence:
- Part of the soil is removed from the pit with a shovel and set aside.
- If necessary, a strong peg is driven in to tie up the pine. When planting tall trees, this is a must, and they use 3 supports driven in by a triangle.
- A seedling is placed in the center.
- Check the position of the root neck – it should be flush with the ground or a few centimeters higher.
- The pit is filled with substrate, compacted from the edge to the center.
- Pine trees are watered abundantly. A bucket of water is spent on a small seedling. For large specimens, at least 10 liters per linear meter of tree growth will be required.
- The soil is mulched with peat, rotted wood chips or pine bark.
Scotch pine planting scheme
In landscape design, the distance between plants is determined by the project. This is the case when a specialist is engaged in landscaping the territory. It takes into account the compatibility of crops, the depth of their roots, the need for nutrients, watering, etc. That is, an experienced landscape designer is able to take into account all the subtleties and nuances of not only the immediate needs of plants, but also how big they will grow, they will not whether to interfere with each other in 5, 10 years or more.
The same is true for park management. But it doesn’t happen there at all that a person from the street is engaged in planning.
What can you advise to amateurs landscaping the site on their own? Need to know:
- Tall varieties are located 4 m apart, for dwarfs the distance is 1-1,5 m.
- Scotch pine loves light and grows quickly. You should not worry that tall varieties will be shaded. But next to the dwarfs, you should not plant fast-growing crops with a wide crown that can block the sun for them.
- The pine root is powerful, even though in culture it adapts to external conditions. That is, it can be more or less branched, predominantly go deep into, or spread to the sides. In any case, it will become difficult for deep-rooted crops planted closely to compete with pine over time – it will simply force them out.Important! When planting together, you should not worry about the pine tree, but about the nearby plant.
- It is impossible to place a culture next to the conifer that requires regular loosening of the soil, especially deep.
- When planting pine hedges, they can be placed no closer than 50 cm from each other, and this is only if the variety is upright, similar to the species plant. For trees whose crown resembles a bush, the distance should not be less than 1 m.
In activities aimed at reforestation in Europe, one of the main species is Scots pine. They have their own rules for placing plants. Pine trees are planted very close to each other so that their crowns close over time.
In this case, the lower branches will die off as soon as the young ones block the sun for them. The tree itself will stretch upwards. This will allow you to get even long logs, almost devoid of branches.
Scotch pine care
The main problem in the cultivation of Scots pine is anthropogenic pollution. Of course, she cleans the air herself, but there is a certain threshold of gas pollution at which she cannot live for a long time. Otherwise, pine is an undemanding crop, with the exception of preventive treatments. It can be left alone for a long time, planted in low-maintenance gardens.
Watering and top dressing
Often, common pine is watered only the first time after planting, especially in spring. When the tree takes root, you need to do this several times a season. Watering is increased in hot dry summer for varietal plants.
They are rarely made, but they spend a lot of water to drink a deeply rooted root. Under dwarfs that have not reached a meter, at least 10 liters are poured. For adult pines, at least a bucket of water is required for each linear meter of growth.
You need to feed the culture up to 10 years of age twice per season:
- in the spring with fertilizers containing mainly nitrogen;
- in autumn, and in the north – at the end of summer, pines need phosphorus and potassium.
Then, with a satisfactory condition of the tree, top dressing can be stopped. But if the condition of Scotch pine leaves much to be desired, or it grows in an ecologically unfavorable environment, it is necessary to fertilize further.
Foliar top dressing is of great importance for pine. They are called fast, nutrients are absorbed immediately through the needles, and when applied under the root, the result will become noticeable after weeks. Foliar top dressing is done in order to:
- increase the resistance of pine trees to stress;
- improve the appearance of the tree;
- give the culture useful substances that it cannot get through the root.
Pine needles can be fertilized simultaneously with treatments for pests and diseases in order to reduce the toxicity of drugs, and if they contain metal oxides, after 7-10 days.
Foliar top dressing is done no more than 1 time in 2 weeks.
Mulching and loosening
The soil under the Scotch pine is loosened until it is fully rooted, that is, two seasons, no more. This is done to break up the crust formed after watering or rains, to ensure the supply of oxygen, moisture, and nutrients to the root.
For Scots pine, soil mulching is a mandatory procedure. Especially if the crown is high. The cover layer will protect the soil from drying out, in winter from the cold, and in summer it will not allow the root to overheat. It will create favorable conditions for the development of a special microflora, prevent the germination of weeds.
Trimming
It is for fast-growing Scotch pine that formative pruning is of great importance. If it is not carried out, all varieties, with the exception of some dwarf ones, will not be able to reach the peak of decorativeness. Skillfully carried out pruning even from common pine will make a unique masterpiece.
It is necessary to pinch or cut trees in the spring, when the young shoot has stopped growing, but the needles have not yet separated from it. The procedure is carried out with a sharp pruner or garden knife, but most people prefer to use their own nails. True, then you need to wash your hands stained with resin for a long time, but this really turns out to be faster and more convenient.
Most sources advise pinching off 1/3 of the shoot. But this is optional. The length of the part to be removed depends on the purpose of trimming:
- A third of the shoot is pinched if they just want to slow down the growth rate of Scotch pine a little and make the crown more lush. At the end of summer or the beginning of autumn, a lot of new buds will form in a circle at the place of the cut, and full-fledged shoots will develop from them next spring.
- Removing 1/2 of a young branch will significantly slow down growth. The tree will become fluffy, with a more accurate crown, dense and compact.
- To form a bonsai-style pine tree, 2/3 of the shoot is removed.
- If the growth of the tree needs to be directed in a certain direction, the kidney must be completely broken. This is what they do when they build a structure next to a pine tree, and they want to prevent the branch from hitting the wall.
Interestingly, it is not necessary to cover the wound surface with garden pitch. Young shoots of Scotch pine emit a lot of resin containing turpentine, disinfect themselves and cover the cut.
“Waste” does not need to be thrown away. If you dry the tips of young shoots of Scotch pine in a sun-protected, well-ventilated place, you can get a good tea supplement containing a lot of useful substances.
Sanitary pruning of common spruce consists in removing dry or broken branches.
Preparation for winter
When planting Scots pine in the recommended frost resistance zone, cover the tree only in the year of planting. In subsequent seasons, they are limited to soil mulching. The layer must be at least 10 cm.
You can increase frost resistance if you feed the pine in autumn with phosphorus-potassium fertilizer. If the autumn is dry, water charging is carried out – this increases the resistance of the tree to low temperatures, avoiding frost holes.
Protection against diseases and pests
In general, Scotch pine is a healthy culture. But it is often affected by rust, which is very difficult to fight, especially near industrial centers – polluted air significantly reduces the tree’s immunity. It is because of this fungal disease that the pines are red and lose their needles.
Of the pests, the already mentioned bud shoot (Evetria turionana), which affects the main shoot, should be mentioned. Because of this, pine trees grow crooked, otherwise their trunk would be stretched out like a string.
To avoid trouble, once in the fall, and twice in the spring, preventive treatments are carried out, dry and broken branches are removed. Pests are fought with insecticides, fungicides will help to defeat diseases.
In order not to stretch the treatments, the preparations can be combined by falling asleep in one bottle, and adding foliar fertilizers, epin, zircon, humate solution. Only those containing metal oxides, namely copper and iron, are used separately.
Reproduction of Scots pine
Reproduction in nature Scots Pine occurs with the help of seeds. The culture is also bred by nurseries. It can be grafted, but the procedure is complicated, and the tree will be short-lived. Scotch pine cuttings are not used for propagation, since their survival rate is extremely low. You can get a new tree from a branch, but it will look like a miracle.
Even varieties are propagated by seeds, and most seedlings inherit maternal traits. But this is not a task for amateurs. After all, seed germination is only 20 percent of success. It is much more difficult to bring them to planting in the ground. And this will take at least 4-5 years, no matter what some sources say.
But no one is allowed to try. And if you really get down to business, it is better to do everything right. Sowing is carried out in early spring in boxes with drainage holes dug in the street, or directly on the garden bed, after changing the soil. The place should be protected from the wind and well lit. It needs free access.
Stratification somewhat increases the germination of pine seeds, but does not significantly affect it. But the risk of damage to planting material at the slightest mistake is great.
It is better to soak the seeds. Many copies are broken in disputes about which water to use – ice or room temperature. The difference is insignificant. Or you can generally put the seeds in a damp, clean cloth for a day.
Damage to the shell is extra work. Scotch pine seeds have a protective cover of such density that it does not prevent swelling or germination.
As a substrate, it is better to take sand, sandy loam, low-lying peat with sand. Amateurs should sow to a depth of no more than 5 mm. It does not prevent the growth of sprouts. At a depth of 2 cm, Scotch pine seeds are sown in nurseries. And they have their own technology, controlled watering, and equipment that is inaccessible (or unnecessary) to amateurs.
With shallow placement of seeds, there is a risk of death of seedlings from overdrying of the soil. Planting needs to be watered frequently. The top layer of soil should not dry out even for a short time.
The seeding rate of Scots pine seeds is 1,5-2 g per linear meter, 2,5-2,7 g per square meter. m. This is quite a lot, since 1000 pieces weigh only 5,5 g. It is clear that when breeding Scots pine, there can be no talk of a sowing scheme.
High-quality Scotch pine seeds will sprout in 14-20 days. When there are a lot of them, the seedlings are thinned out, leaving 100 pcs. per 1 running or square meter.
After the sprouts shed the seed coat and straighten up, they are fed with a weak solution of complex fertilizer. Scotch pine picking can be carried out at the youngest age, when the seedlings reach a height of 3-4 cm, or left in a box until the start of the next season. At the same time, they should be regularly fed, since the substrate is not able to provide the culture with nutrients due to its composition.
A pick is carried out in light soil with the addition of a large amount of sand. As a container, you can take plastic cups with a volume of 100 ml, if it is possible to water the pine seedlings daily, and in hot summer – several times a day. Containers of 200 ml are taken when seedlings are less likely to be moistened. It is imperative to make a hole in them for the outflow of water and put drainage.
Now about shortening the roots. In a seedling 3-4 cm tall, it can reach 10 cm or more, it all depends on the depth of the box. In the ground, the root will definitely be long. What can you do, in pine it is pivotal, and this manifests itself from a very early age.
The root can break when digging seedlings, if not too short, then not scary. Pinch it depending on the depth of the container. You can leave it as it is, or 5-7 cm on a 3-4 cm seedling. With a properly made pick, the survival rate is 80% or more. For Scotch pine, this is an excellent result.
Seedlings from a small (100 ml) container will have to be transferred to a larger volume in a year or two. Cups of 200 ml should be enough before planting in a permanent place.
Care consists in top dressing 1-2 times per season, treatments for pests and diseases, protection from strong and drying winds, and regular watering. Of course, common pine is a drought-resistant crop, but if the seedlings are not watered in time, they will die.
Finally, I would like to remind you that it is better to sow pine seeds on the street. If boxes are used for this, they are dug in in a quiet sunny place. Indoors, seedlings will grow weak and may die after transplanting to a permanent location. Of course, this does not apply to nurseries, where the premises are specially adapted.
For the winter, seedlings of Scotch pine are covered with spruce branches.
The use of Scots pine
It is difficult to overestimate the Scotch pine. It is of great economic importance, is one of the main forest-forming species for Europe, and a valuable ornamental species.
Scotch pine in the national economy
Wood is the cheapest and most commonly used building material, it is from it that cellulose is obtained, plywood is made.
Hydrolysis alcohol is produced from sawdust.
Resin is a valuable raw material for the chemical and medical industries; turpentine, essential oil, and rosin are extracted from it.
Medicines are also made from cones, young shoots and needles.
Even from mature needles they make a vitamin supplement for livestock feed.
Scotch pine as a forest-forming species
In Europe and northern Asia, the culture is widely used, especially on sandy soils. It is planted to strengthen slopes, prevent soil erosion, and simply where nothing else will grow.
Scotch pine can form clean plantings, but does well next to other conifers and deciduous trees.
Scotch pine in urban landscaping and park management
Here the importance of culture is small. This is not due to decorative qualities or the complexity of care. Scotch pine does not react well to air pollution, and in industrial centers or near highways it can quickly die, leaving behind bare dry trunks with branches sticking out to the sides.
The culture is planted on the territory of botanical gardens, inside the park area, where the air has already been cleaned by other deciduous and coniferous trees. It will grow satisfactorily in those areas of the city where the wind rose does not bring gas from car exhausts and smoke from industrial enterprises.
Scotch pine in landscape design
If the ecological situation allows, the culture will become indispensable for landscaping a large area. On a small one, you can plant dwarf varieties.
Even from a fast-growing species tree, it is easy to form a beautiful tree. And skillfully using pruning of young shoots, you can significantly slow down the rate of plant spread upwards and make the crown dense.
Scotch pine is planted as a tapeworm, as part of landscape groups. Depending on the variety, it can favorably emphasize the beauty of other cultures, or focus attention on itself.
Conclusion
Scotch pine is a valuable crop for decorative landscaping, drought-resistant, undemanding to soils and care. It would be used much more widely with better air pollution tolerance.