How long do oak trees pollinate

Oak tree allergy - a quick guide w/ photos. » Allerma™

In this article, we will learn to identify oak trees (scientific name: Quercus) as well as how and when their pollen spreads.

Oak (Genus: Quercus)Pollen allergy profile
Pollen seasonSpring, Summer
Pollination typeWind pollinated. Each tree releases a large amount of pollen into the air
Cross-reactivity with other pollenWithin the same family Fagaceae (Oak, Chestnut, Beech), but also possible with Betulaceae (Birch, Alder)
Pollen sourceMale flowers (catkins) develop during winter and release pollen during spring or summer (see pictures below.)
GenderMonoecious: Separate male and female flowers on the same tree.
FruitAcorns: Oaks are the only trees that produce acorns (see pictures below).
LeavesRounded lobs (white oaks) or Pointy lobs (red oaks), but other forms possible (see pictures below.)

How to identify an oak tree (Genus:


The oak trees have over 450 species worldwide and about 60 of them are in the US alone.[3][R1] Identifying the exact species of an oak tree can be tricky because it hybridizes easily [R1]. Oak trees are found all over the US except Hawaii and Alaska [R1] and this is why oak tree allergies are common.

The most distinct feature of an oak tree is an acorn, its fleshy fruit with a scaly cap on the top. However, a tree has to be twenty to fifty years old to produce acorns. Thus, we have to learn to identify its leaves, which, as shown in the picture below, come in many sizes and shapes.

Some of the oak species are deciduous and some are evergreen (e.g. Coast live). Some do change color during autumn (e. g. Scarlet and Pin) and some remain green.

The leaves of oaks shown in the picture are all collected from an area within a 5-mile radius of my lab. This is how diverse looking this genus of the tree is.

Some species form the group called “Red oaks” and they have several lobes with pointy tips. The examples of species that fall in the “red oaks” category are Scarlet, Pin, and the Northern oaks (#4, 5,10 in the picture below).

Some species form the group called “White oaks” and they have several round-tipped lobes. The examples of “White oaks” are English and Valley oaks (#1 and 2 in the picture below).

There are other species such as Coast live, cork, Holly that do not neatly fit into the red or white oak groupings because they do not have leaves with multiple lobes. Most, however, will have tiny spikes on the edges of the leaves (#3,6,8,9 in the picture below)

Leaves and fruit

Oak tree leaves and acorns.

Tree size and shapes

With over 450 species in existence, it is rather difficult to describe oak trees. Some oak trees live up to their reputation and are indeed mighty, and some not so much.

Here are pictures of three different oak trees just as an example.

Coast live tree (Quercus agrifolia).Shumard oak tree (Quercus Schumardii)Scarlet oak tree (Quercus coccinea) during fall.

Bark and trunk

For an allergy sufferer, it is not practical to rely on the bark or trunk to identify an oak tree. The barks and trunks are so different from one tree to the other that it is not an easy trait to master. We leave that to the experts. I have found acorns and leaves to be enough to identify an oak tree.

But for the curious minds, here are examples of the bark of three different species of oak trees. As you can see, each one of them is remarkably different from the other.

Coast live oak tree trunk (Quercus agrifolia)Cork oak trunk (Quercus suber)Northern oak tree trunk (Quercus rubra)

During which months oak trees release pollen?

Different species of oak trees release pollen from early spring to early summer.

In the San Francisco bay area, oak pollen is found in our air surveys from Mar-15th to June-30th.

Even though each tree release pollen only for six to eight weeks, the overall oak pollen season lasts nearly four months because of the sequential blooming of different species. In Northern California, the coast live species start the oak pollen season in March, and Holly and cork oaks end the pollen season in June. Most other red and white oak species bloom during April and May.

Each year, the pollen season shifts a little bit due to weather conditions. Therefore it is useful to learn about the oak trees and their pollen-producing habits to be able to accurately predict the pollen season each year.

However, if you live in the San Francisco Bay Area, you have an easier way out! I do regular tree inspections and air sampling in the area to provide reliable pollen updates on our website

How does oak pollen spread?

Oak trees release pollen into the air and wind can carry the pollen many miles.

Since the tree is widely present in the mainland USA, its pollen is expected to be in the air surveys everywhere during spring and early summer.

When compared to other allergy plants, iIn most US cities, oak produces one of the largest pollen loads as well as the longest pollen season.

What does oak pollen look like?

The male catkins release pollen in the form of fine yellow powder. However, once the pollen disperses in the air, it becomes invisible to the naked eye.

Each oak pollen grain is around 30 micrometers (0.03 mm) in size and has three furrows. It has a warty exterior surface. Quercus pollen: Tricolpate (some scientific literature considers it tricolporate) with verrucate exine.

Live Coast Oak Pollen at ~400x magnification.

How do you know if oak tree is releasing pollen?

The tell-tale sign of an oak tree releasing pollen is the presence of male flowers (catkins) on its twigs. When the catkins first appear on the trees, they are like green beads hanging in groups (first picture) and are still too young to release pollen.

When the catkins turn yellow and have a brush-like appearance, they are mature and capable of releasing pollen (second picture).

Mature catkins eventually fall on the ground. If you suffer from oak tree allergies, be especially careful on days when the leaf blowers or street cleaners come and disturb these catkins on the ground.

Young male catkins of oak.Mature, pollen releasing, catkins of oak.

Final thoughts

Oak (Genus: Quercus) is an important allergen in the US, and in the world, because of its widespread presence.

Furthermore, it belongs to the order Fagales, which means if you have oak tree allergies, it is possible for you to have allergies or cross-reactivity to other genera of the same order such as Birch, Alder, Walnut, and Casuarina[R4].

I have also written about Chinese Pistache (Pistacia chinensis), Sycamore (Platanus), Sweetgum (Liquidambar styraciflua), Hackberry (Cletis), and Olive (Olea Europaea) trees that release pollen at the same time as some of the species of oak.




  1. Allergy Plants by Mary Jelks, M.D.
  2. Plant identification terminology by James G. Harris and Melinda Woolf Harris (Second Edition)
  3. Sampling and indentifying pollens and Molds by E. Grant Smith
  4. Hay Fever by Jonathan Brostoff, M.D and Linda Gamlin

All pictures, unless otherwise credited to another source, are taken by the author and are copyrighted material. The pollen picture is taken in our aerobiology lab using an Olympus compound microscope.

Mating in Single Oaks | International Oak Society

Sometimes one encounters a single, isolated individual tree, thriving in a private collection as the only representative of its species. The proud owner admires and perhaps even pampers it. But little thought is given to it besides the esthetic, botanical or horticultural merit of such a plant.

It is this case of a single individual that I would like to consider here, specifically the isolation of the species and the significance and biological interest of the reproductive barriers that prevent it from crossing with other species.

The author with Quercus pontica in the Jerusalem Botanical Garden

Oaks are wind-pollinated trees with male and female flowers on the same tree. But in spite of this fact they set fruit usually only when another individual of the same species exists in the vicinity and can serve as a pollen donor. The phenomenon is known as self-incompatibility and the plants distinguished as such are defined by geneticists as outcrossers. However in some rare cases this pattern is not true and according to a recent study[i] a few cases (3.5%) of self-pollination give rise to viable acorns.

Outcrossing is a well-known phenomenon, familiar in agricultural practice since antiquity and found later in many other wind-pollinated arboreal (date palms) and insect-pollinated herbaceous plants (irises).

In nature, for example in Southern Europe, closely related trees often grow together in the same or nearly the same habitat. If, like in oaks, the reproductive barriers that isolate the different species and maintain their distinctive morphological features are weak, the result is the development of a whole series of intergrading forms defined by science as a hybrid swarm – the result of a powerful evolutionary process known as introgression. A recent publication[i] considers all these aspects in an experimental context.

Quercus agrifolia acorn

In gardens and plant collections, (and also rarely in nature!) actually two different pollinating scenarios can be described: that of a single specimen of oak in an environment devoid of oaks and another one of an isolated plant in a collection of other oak species. I have experienced both cases.

The first type is encountered with foreign, introduced oak trees in Israel. They were in the past handed out to gardeners to test their suitability for horticultural practice in different parts of Israel. A suitable case for this situation is a single, sexually mature specimen of the evergreen Californian Quercus agrifolia Née growing at Kibbutz Horshim in the coastal plain of Israel, north east of Tel Aviv, since 1985.

The second type of case is the single, sexually mature, deciduous plant of Q.pontica K. Koch cultivated at the Jerusalem Botanical Garden. In both cases the characteristic outcrossing mating system of oaks produces two profoundly different results:

a) The Q. agrifolia in the coastal plain of Israel is exposed to only three types of pollen donor: the native evergreen Kermes oak (Quercus coccifera subsp. calliprinos (Webb) Holmboe), the cork oak (Q. suber L.) and the holm oak (Q. ilex L.) – all characteristic and ancient natives of the Mediterranean region and not native to California. But in spite of this fact the tree is heavily loaded with perfectly viable acorns.

Female inflorescence on Quercs pontica in Jerusalem Botanic Gardens

b) Contrarily, the tree in the Botanical Garden grows in the immediate close proximity of a significant number of mature trees from different deciduous European species – but is absolutely barren of any ripe acorns! Though it usually flowers, any pollinated female flowers are aborted and shed in the course of the summer.

These two examples can be interpreted in different ways, but there can be no doubt that their significance and interest is much greater than what the casual observer might think. For example, let us consider the case of the Californian and the native Israeli or Mediterranean species: all evolved under very different geological historical scenarios. If they are compatible it means they share not only the same chromosome number but much more in their molecular makeup. Given that all three Israeli species represent a very ancient element (probably Miocene) in the circum-Mediterranean Flora, this makes the elucidation of the phylogenetic background most interesting in its implications.

Quercus agrifolia seedling

The first scenario that comes to mind is one where all of the four species share the same chromosome type and the same type of pollen grain. The ability of the Israeli species to pollinate and fertilize the Californian species – and to a lesser degree the cork oak – while holm oak remains sterile and isolated, might indicate their very ancient origin from times before the breakup of the ancient single continent, when their distribution comprised all the Northern Hemisphere.

Other mating patterns could be described, but all would need critical experimental verification.

To sum up: watch the mating of your isolated species – they could tell a fascinating story.


Editor's note: The author now considers that the tree of Q. agrifolia may be self-compatible and could have pollinated itself. 


[i] Lapais, O., G. Roussel, F. Hubert, A. Kremer and S. Gerber, Strength and variability of postmating reproductive isolating barriers between four European white oak species, Tree Genetics & Genomes, 2013,Vol. 9, Issue 3: 841-853.


Oak, pollen

Common oak blossoms in the middle lane at the end of April - in May, simultaneously with leaf blooming. After the opening of male flowers, pollen remains viable for about 5 days; it is favored by high temperature and wind; pylopio decreases or even stops during drizzling rain (anthers often open) and during frosts mass abscission of inflorescences may begin. Pollination in large trees usually lasts several days, but in some American shrub oaks, in favorable weather conditions, it is smoked in a few hours. Protandry is often observed in oaks - usually the anthers have already shed their pollen when the stigmas of the female flowers of the same shoot are still quite poorly developed.[ ...]

Fossil plant pollen provides excellent material for the reconstruction of terrestrial plant communities that have existed since the Pleistocene. Retreating, the ice often left depressions, which then turned into lakes. The pollen of plants growing around the lake sinks to the bottom and is fossilized in bottom silt. Such a lake can gradually fill up and turn into a swamp. A vertical section of a swamp or the bottom of a lake gives us a chronological sequence of events by which we can determine the ratio of pollen of different species at different times. Their replacement by oak, hemlock and beech pollen indicates that a warm, humid climate prevailed several thousand years ago. At the same time, the predominance of oak and hickory pollen indicates a warm dry period, which later gave way to a somewhat colder and more humid climate in the most recent part of the profile. Finally, the pollen "calendar" clearly reflects the results of recent human deforestation - the pollen content of herbaceous plants has increased in the samples. The pollen charts of Europe even registered the effects of the smallpox epidemic, which led to the decline of agriculture. This was reflected in a decrease in the proportion of herbaceous pollen in sediments dated to the same time as the mass death of people.[ ...]

Spore-pollen analysis revealed a small amount of pollen, with many torn, deformed, flattened, and therefore undetectable grains. Among tree forms, except birch pollen and s[ ...]

Odorous rue. Sumac is poisonous. Cow parsley. Pollen from birch, oak and elm. Cork dust. Peat dust.[ ...]

Insulation « 800-500 m is considered sufficient for this purpose. To illustrate the possibility of wind blowing over long distances, the fact that a large amount of oak pollen was brought to Heligoland from the neighboring mainland at a distance of about 00-70 km from the nearest oak plantations is usually cited. Cases are known of the deposition of tree pollen into the Arctic for many hundreds of kilometers. Facts:> but subject to doubt. However, the biological significance of long-range aerial transport of pollen is highly questionable for the purpose of pollination. Pollen, being in the air, will quickly lose viability, as has been established for cereals. Effective cross-stunning with the help of the wind is carried out at a small distance, between the nearest individuals, separated from each other by at most a few tens or hundreds of meters.[ ...]

Consequently, the landscape of the territory was dominated or dominated by forests of the boreal type, formed by pine, birch with the participation of spruce] broad-leaved species such as oak, elm, linden and hazel. Noting! a high percentage of pollen from herbaceous plants and, first of all, cultivated cereals and associated weeds. The presence of cultivated cereals in large aggregations in the dust spectrum indicates a small pollen transfer, which can only be associated with the close location of the arable wedge.[ ...]

The spectrum of sample no. 5, selected in the humus horizon along the swell formed on the surface over the past 2000 years, contains a large number of well-preserved microfossils. In general, cocí is dominated by tree pollen (54.9%). In the first place is ss (43.9%), then birch (33.7%) and spruce (12.1%), broad-leaved species, especially oak, are quite fully represented. Pollen from cultivated cereals than in the pre-raked soil (29.7% vs. 9.1%) there are also many of their companions, weeds such as Polygonum aviculare, Centaurea cyanus, Chenopodium album.[ ...]

Age structure of the population - the ratio in the composition of the population of individuals of different ages, representing one or different offspring of one or several generations. A generation may consist of individuals of the same offspring and of individuals of different offspring (for example, in small mammals). But the offspring can also consist of individuals of different generations: an acorn that has fallen from a 1000-year-old oak will germinate, and in 20 years the pollen of a young oak can pollinate the flowers of the parent tree, which is 50 generations older.[ ...]

The various relationships of beneficial mutualism involve plants and animals that either pollinate plants or carry their seeds. Such relationships are not symbiotic in the usual sense, since in these cases there is no close and continuous joint connection between individuals of the two species. Nevertheless, two species may be in some way dependent on each other and adapted to each other. The squirrel both eats acorns and accidentally plants them when he buries them in reserve and then forgets about some of them. The squirrel is to some extent dependent on the oak for food; at the same time, the oak is provided with more efficient seed dispersal. Many of the amazing adaptations in terms of color, shape, and food offered (nectar or pollen) of plant flowers are associated with the behavior of the animals that pollinate them. In the tropics, many of these adaptations are highly specialized. Pollination is a type of mutualism in those organisms that do not live in constant contact: the animal receives food, and the plant, with the help of the animal, carries out fertilization. Pollination, however, is also a special form of parasitism. Some bees and other animals feed on nectar and pollen, but do not transfer pollen from one flower to another. In this case, the plant species that provides food to the animal has evolved, participating in interactions with both pollinators and consumers of pollen or nectar that are not involved in pollination.[ ...]

The beginnings of male beech inflorescences are laid in the summer of the year preceding flowering in the emerging buds, the beginnings of female - much later. In the eastern beech (P. opalina) male inflorescences are laid in June, after the end of the formation of the covering scales; the process of formation of male inflorescences lasts 2-3 months, and already in August, when the buds are opened, inflorescences with anther rudiments can be found. In autumn and winter, further differentiation of tissues takes place, which is flooded with forest. So, the cycle of development of male inflorescences takes V-10 months. In one bud, up to (> inflorescences can overlap. The rudiments of female inflorescences appear a month later than male ones, when 2-3 embryonic leaves have already been formed in the bud. Female inflorescences are laid in the form of meristomatic tubercles in their axils. up to a year, causing the following year a large influx of carbohydrates to the nights and abundant fruiting.For the normal development of female inflorescences, beech, like oak, needs low temperatures in winter (at least a few hundredths of hours).Differentiation of inflorescences is completed only in spring, after the establishment of stable positive temperatures. Leafing and flowering of eastern beech occurs in early May.Most of the shoots with female inflorescences are located on the terminal parts of the branches;shoots with male inflorescences are located along the entire length of the branch, mainly in its lower part.Male flowers usually open for 3-4 days earlier than women's In rainy weather, dust-n Iki open in the lower part of the crown, in the sun - in the upper. Beech pollen dies both from excessive dryness of the air and from excessive moisture.[ ...]

Oak is a symbol of power and longevity. Cultivation, reproduction. Diseases and pests. Oak bark application, decoction. Kinds. Photo - Botanichka

There are several interesting facts about oak: At the Paris exhibition in 1900, an oak ridge sawn from a 485-year-old oak 31 m high and 169 cm in diameter was shown. that is, on the territory of the modern Shumerlinsky forestry enterprise of the Chuvash Republic.

And in 1861, in the Yadrinsky district of the Kazan province, an oak “50 feet long” (that is, 15 m high) and “48 inches in the upper cut” (213 cm in diameter) was cut down. This tree was counted 500 years old, at that time it was completely fresh, healthy and still growing in volume ...

Oak was a sacred tree of many peoples, including the ancient Slavs and Celts, it was worshiped as a deity. Even today it remains a symbol of courage and resilience, and not just, so to speak, “impenetrability” ... By the way, to see an oak strewn with acorns in a dream - to well-being and career growth.

Pedunculate oak (summer, English, common) (Quercus robur). © Leafland

Botanical description

Oak ( Quercus ) is a genus of deciduous or evergreen trees of the beech family. The leaves are alternate, simple, pinnatipartite, lobed, serrated, sometimes entire. Oak flowers are small, inconspicuous, same-sex, monoecious; staminate - in long hanging catkins, pistillate - single or several, sessile or on a pedicel. The fruit is a single-seeded acorn, partially enclosed in a cup-shaped woody cupule.

Oak grows slowly, at first (up to 80 years) - stronger in height, later - in thickness. Usually forms a deep tap root system. Gives abundant shoots from the stump. Photophilous. Some types of oak are drought-resistant, quite winter-hardy and not very demanding on soils. It begins to bear fruit at the age of 15-60, in open places earlier than in plantations. It reproduces mainly by acorns. For sowing, acorns collected in the same year are used, because. they quickly lose their viability. There are about 450 species of oak in the temperate, subtropical and tropical zones of the Northern Hemisphere. In Russia - 20 (according to other sources, 11) wild species in the European part, the Far East and the Caucasus; 43 species of oaks are grown in culture.

Most important in forestry is English oak , or summer ( Quercus robur ), - a tree up to 40-50 m high and 1-1.5 m in diameter. The leaves are elongated obovate, with 5-7 pairs of short lobes , on petioles up to 1 cm long. Acorns 1-3 on the stalk. Blossoms simultaneously with the blooming of leaves from 40-60 years. Fruits abundantly every 4-8 years. Grows fairly quickly in side shade, but requires good light from above. Lives up to 400-1000 years. Distributed in the European part of Russia, in the Caucasus and almost throughout Western Europe. In the northern part of the range it grows along river valleys, to the south it goes to watersheds and forms mixed forests with spruce, and in the south of the range - pure oak forests; in the steppe zone it occurs along ravines and gullies. One of the main forest-forming species of broad-leaved forests in Russia.

Similar to Pedunculate Oak Rock Oak , or winter ( Q. petraea ), with almost sessile (2-3 each) acorns, found in the west of the European part of Russia, in the Crimea and the North Caucasus. Georgian Oak ( Q. iberica ) grows in the eastern part of the North Caucasus and Transcaucasia with leathery leaves and sessile (1-2) acorns; Large anthered oak ( Quercus macranthera ) grows in the high mountain zone of these regions with densely pubescent shoots and sessile acorns or on a short stem. The main species of the valley forests of Eastern Transcaucasia - Long-legged oak ( Q. longipes ). An important forest-forming species of the Far East - Mongolian Oak ( Q. mongolica ) - frost-resistant and drought-resistant tree.

Oak wood has high strength, hardness, durability and a beautiful texture (cut pattern). It is used in shipbuilding, for underwater structures, because. does not rot; used in car building, in furniture, carpentry, cooperage, house building, etc. Some types of bark ( Cork oak - Q. suber) gives a cork. The bark and wood contain tannins (tannins) used for tanning hides. The dried bark of young branches and thin trunks of English oak is used as an astringent in the form of an aqueous decoction for rinsing in case of inflammatory processes in the oral cavity, pharynx, pharynx, as well as for lotions in the treatment of burns. Acorns are used as a substitute for coffee and as food for pigs and some other agricultural products. animals. Many species, such as Chestnut oak (Q. castaneifolia), are bred in gardens and parks as ornamental plants.

Growing oak

Oak acorns, unlike the seeds of the vast majority of our other trees, do not remain viable when dried and stored for a long time at room temperature. Therefore, it is necessary either to sow them in the fall before the snow falls and the soil freezes, or to provide them with special storage conditions. Autumn sowing is the easiest, but there is a serious risk of damage to some of the acorns by rodents.

For spring sowing oak acorns must be properly preserved. The best storage conditions are at low (about 0° or slightly above) temperature, high humidity and moderate ventilation. Acorns can be stored in the basement, where potatoes are well preserved in winter; you can also dig them into the soil in the fall to a depth of at least 20 cm, covering the top with a sheet of waterproof material, leaving a layer of air between this sheet and acorns and providing protection from mice. In any case, healthy acorns without external damage should be stored for winter storage, preferably collected in dry weather and dried at room temperature for a week. Any special preparation of seeds that have survived the winter is not required before sowing.

Before sowing, evaluate the quality of the acorns by opening a few of them. Live oak acorns have yellow cotyledons, and at the place of their connection with each other there is a live (yellow or red-yellow) embryo. Dead acorns are black or grey. By external signs, it is not always possible to distinguish living acorns from dead ones. Soaking acorns in a container of water gives good results - dead acorns mostly float, live ones mostly sink (if there are a lot of acorns, then this method of separating the dead from the living is quite recommended, but a small part of the live acorns will be lost).

If you have not been able to stock up on acorns since autumn, then in some years (after a large harvest of acorns and under the condition of a “crop failure” of mice, and if the winter was not very frosty), you can collect live and germinating acorns in the spring in the nearest forest or park. It is necessary to collect germinating acorns in early spring, almost immediately after the snow melts, otherwise you will find damaged roots in many acorns. Collected oak acorns must either be sown immediately or stored until sowing in such a way that the roots do not dry out (for example, mixed with wet leaves in a plastic box put in a refrigerator or a cold basement). Even with short-term storage, it is necessary to ensure that germinating acorns do not become moldy (throw away damaged ones immediately), and ensure their ventilation. The faster you can sow the acorns collected in the spring, the more of them will be able to develop into seedlings.

Oak acorns. © TwidOak sprouted acorn. © Beentree

Sowing acorns

When sowing acorns, mark out parallel furrows 15–25 cm apart in the bed. Arrange the acorns in the furrows at the rate of 15-50 pieces. per 1 m of the length of the furrow, depending on the quality and size (if the acorns are large and almost all live, then they should be laid out less often, if small and with a large proportion of dead and doubtful - thicker). If you plan to plant annual oak seedlings in a permanent place, then acorns should be sown even less often - at a distance of 7-10 cm from each other (this will ensure the maximum growth of each tree). Press the acorns into the bottom of the furrow so that they are at a depth of 2–3 cm from the soil surface in spring planting and 3–6 cm in autumn. After that, level the furrow by covering the acorns with earth.

Acorns germinate for a very long time. First, they develop a powerful root, reaching a length of several tens of centimeters, and only after that the stem begins to grow. Therefore, oak sprouts can appear on the soil surface only a month and a half after the start of germination. Do not rush to conclude that your oak trees have died and dig up a bed with crops (as the experience of novice amateur foresters shows, this happens). If in doubt, try digging up some acorns. If their roots have grown, then the acorns are alive.

Care of oak seedlings

Oak seedlings suffer much less from weeds and drying out of the soil than coniferous trees (due to the supply of nutrients in the acorn, large roots and leaves immediately develop). However, try to always keep crops free of weeds and ensure watering during severe drought, especially if you want to get large seedlings in one year. Stop any additional watering about a month and a half before the time when mass leaf fall begins in your area - this will allow oak seedlings to better prepare for wintering (too late growths in oak often freeze out in winter).

In summer, oak seedlings are often affected by powdery mildew, a fungal disease. Powdery mildew is not able to kill oak seedlings, but can significantly reduce their growth. With a strong development of powdery mildew (if white bloom covers more than half of the area of ​​​​all leaves), seedlings can be treated with a 1% solution of copper sulfate or a 1% suspension of sulfur. Oak seedlings can be grown for two years in one place without a transplant, or they can be transplanted in the second year into a "school". The second method is preferable, because it allows you to form a more compact and branched root system, which suffers less when transplanted to a permanent place (for two-year-old seedlings grown without transplantation, the length of the main root can be more than a meter, and it is almost impossible to transplant them without damaging the root).

Oak seedlings should be transplanted into the “school” in spring, preferably as early as possible, so that the root system damaged during transplantation has time to partially recover even before the leaves bloom (it is also important that the soil is still moist during transplantation). When transplanting, cut off the main root of each oak seedling at a distance of 15-20 cm from where the acorn was located (in most seedlings, the remains of an acorn in the second year are still visible). This will form a more compact root system. It is possible not to cut the main root, but in this case it will be very difficult to dig up two-year-old seedlings without serious damage to their root system.

Oak seedlings. © Elektryczne jabłko

Place rows of seedlings at a distance of 25–30 cm from each other in the “school”, and seedlings in a row at a distance of 12–15 cm. When planting under each oak seedling, make holes 20–25 cm deep with a stake or spade handle ( the depth of the hole should be such that when the seedling is planted, the place of attachment of the acorn is 2-3 cm below the soil surface). Insert the seedlings into the holes (the main root of oak seedlings, unlike the root of conifers, is hard and straight and inserted into the holes without problems). Then fill the holes with earth and compact it with your hands so that the earth fits snugly against the roots of the seedlings.

Transplanted oak seedlings in the first weeks after transplantation suffer greatly from root damage - leafing is rather slow, and shoot growth is relatively small. Nevertheless, by mid-summer, the normal development of seedlings is restored, and by autumn, as a rule, large seedlings (30–50 cm high) are quite suitable for planting in a permanent place. If the size of the seedlings by autumn leaves much to be desired, then only the largest ones can be selected for transplantation, and the rest left in the "school" for another year.

If you are transplanting annual oak seedlings to a permanent place (this is quite possible if planting is done in areas with low grass cover or plowed soil), then do not cut the main roots of the seedlings - try to keep as much of their length as possible. The root system of an annual oak seedling is represented mainly by a long and straight taproot with weak and short lateral roots, therefore, for transplanting, it is enough to make a narrow hole of the appropriate depth using a stake or a shovel handle.

Oak species

English oak (summer, English, or common) - Quercus robur

Occurs naturally in the European part of Russia, Central and Western Europe. A very powerful tree up to 50 m tall, in closed plantations with a slender trunk, highly debranched, in single plantings in open places - with a short trunk and a wide, spreading, low-set crown. Lives 500-900 years.

English oak (Quercus robur). © 2micha

The bark on trunks up to 40 years old is smooth, olive-brown, later grayish-brown, almost black. The leaves are alternate, at the top of the shoots close together in bunches, leathery, oblong, obovate, up to 15 cm long, with an elongated top and 3-7 pairs of obtuse, lateral lobes of unequal length. Lobes entire or with 1-3 teeth, often with auricles at the base of the leaf blade. The leaves are shiny, bare, dark green above, lighter below, sometimes with sparse hairs. In spring, the oak blossoms late, one of the last among our trees. Oak blossoms in April-May, when it still has very small leaves. The flowers are unisexual, monoecious, very small and inconspicuous. Male or staminate flowers are collected in peculiar inflorescences - long and thin, yellowish-greenish drooping catkins, reminiscent of hazel catkins. Acorns up to 3.5 cm, 1/5 covered with a cupule, ripen in early autumn.

Grows slowly, the greatest energy of growth in 5-20 years. Moderately photophilous, wind-resistant due to powerful root system. Excessive waterlogging of the soil does not tolerate, but withstands temporary flooding for up to 20 days. It prefers deep, fertile, fresh soils, but is able to develop on any, including dry and saline ones, which makes it indispensable in green building in many regions of Russia. It has high drought and heat resistance. One of the most durable breeds, some sources indicate a life expectancy of up to 1500 years.

Possesses powerful energy. Oak in Russia was considered a sacred tree. In the springs located in the oak forests, the water has an excellent taste and is particularly clean.

Propagated by sowing acorns, decorative forms - by grafting and green cuttings. It is well renewed by shoots from a stump. Acorns do not tolerate desiccation, as soon as they lose even a small part of the water, they die. In heat, they easily rot, they are very sensitive to cold and frost. This circumstance presents a certain difficulty for preserving acorns for seeds. In nature, there is no such problem: acorns that have fallen in late autumn in the forest overwinter in a wet bed of leaves under a thick layer of snow that protects them both from drying out and from frost. The germination of an acorn resembles the germination of a pea: its cotyledons do not rise above the soil surface, as in many plants, but remain in the ground. A thin green stem rises up. At first it is leafless, and only after some time small leaves appear on its top.

Red oak (Quercus rubra)

It occurs naturally along river banks, where there is no stagnant water in the soil, north of the 35th parallel of the North American continent, up to Canada. Tree up to 25 m in height.

A slender tree with a dense hipped crown.

Red oak (Quercus rubra). © Jean-Pol GRANDMONT

The trunk is covered with thin, smooth, gray bark, cracking in old trees. Young shoots are reddish-felt, annual shoots are red-brown, smooth. The leaves are deeply notched, thin, shiny, up to 15-25 cm, with 4-5 pointed lobes on each side of the leaf, reddish when blooming, dark green in summer, lighter below, in autumn, before falling off, scarlet-red in young trees , in old ones - brownish-brown. Blooms at the same time as the leaves open. Acorns are spherical in shape, up to 2 cm, red-brown, as if chopped off from below, unlike English oak, they ripen in the fall of the second year. It bears fruit steadily and abundantly from 15-20 years. When young, it grows faster than European oaks.

Frost resistant. Medium light-loving, easily tolerates lateral shading, but prefers full coverage of the top of the crown. Not drought tolerant. Wind-resistant, not very picky about soil fertility, can withstand even an acidic reaction, however, does not tolerate calcareous and wet soils. Resistant to pests and diseases, including powdery mildew - the scourge of our oaks. It has high phytoncidal properties. Due to its high decorativeness, resistance to adverse environmental factors, magnificent autumn decoration, it deserves the widest use in green building, for creating single and group plantings, alleys, arrays, lining roads and streets.

Downy oak (Quercus pubescens)

Naturally found in the southern Crimea, the northern part of Transcaucasia, Southern Europe and Asia Minor. Tree up to 10 m tall. Durable.

Downy oak (Quercus pubescens). © Petr Filippov

Significantly inferior in size to the previous species, with a low, winding trunk and a wide crown, sometimes even a shrub. Young shoots are strongly pubescent. Leaves 5-10 cm long, very variable in shape and size, with 4-8 pairs of obtuse or pointed lobes, dark green, glabrous above, grey-green below, pubescent. The scales of the plush surrounding the acorn are also fluffy.

It grows slowly, loves light and heat, lives on dry stony slopes and soils containing lime. Handles haircut well. Valuable species for green building in arid areas, grows on stony soils where other species do not develop. An excellent material for high hedges and figured, sheared forms.

White Oak (Quercus alba)

Native to eastern North America. Grows in forests with other types of oak and hazel, on various soils, but better on deep, rich, well-drained, limestone; in the north of the range it is distributed no higher than 200 m above sea level. sea, in the south up to 1500 m a.s.l. seas.

White oak (Quercus alba). © Msact

Large beautiful tree up to 30 m, with powerful spreading branches forming a wide, tent-shaped crown. The shoots are bare, the bark of the trunk is gray, shallowly cracking. Remarkable for very large, oblong-oval leaves, up to 22 cm, with 5-9 obtuse lobes; when blooming - bright red, in summer - bright green, with a whitish-gray underside. In autumn, the leaves turn dark red or purple-purple. Acorns up to 2.5 cm, a quarter covered with a plush. Seeds are stored for spring sowing in semi-moist sand. In autumn, sown immediately after harvest and air drying. Germination of seeds is maintained until the spring of next year. Ground germination 80 - 85%. Embedding depth s. 5 - 6 cm.

Marsh oak (Quercus palustris)

Homeland North America.

A slender tree up to 25 m tall, narrowly pyramidal when young, later broadly pyramidal. Young shoots are thin, hanging, reddish-brown. The bark of the trunk is greenish-brown, and remains smooth for a long time. Leaves up to 12 cm long, with 5-7 deeply cut, almost to the middle of the leaf, toothed lobes, bright green above, lighter below, with tufts of hairs in the corners of the veins. In autumn they are bright purple. Acorns sessile, almost spherical, up to 1.5 cm, 1/3 covered by a cupule. Seeds are stored for spring sowing in semi-moist sand. Autumn with. sown after harvest and air drying. Germination of seeds is maintained until the spring of next year. Ground germination with. 80 - 90%. Embedding depth s. 5 - 6 cm.

Swamp oak (Quercus palustris). © Willow

Fast growing, less hardy than red oak and northern oak. It is more demanding on the soil and its moisture, as it grows in nature on deep, moist soils on the banks of rivers and swamps. It tolerates city conditions well. Looks great in single, group and avenue plantings, along the banks of reservoirs. In culture since the middle of the XVIII century. Grows in the parks of Ukraine (Chernivtsi), Belarus, Voronezh region. It freezes in St. Petersburg.

Willow oak (Quercus phellos)

Wildly grown in eastern North America.

A beautiful deciduous tree up to 20 m tall, with a slender trunk and a wide-round (pyramidal in youth) crown. Remarkable original shiny green leaves resembling willow leaves (up to 12 cm long by 2 cm wide). This similarity is even more enhanced in young leaves, strongly pubescent below. In autumn, the leaves turn dull yellow.

Willow oak (Quercus phellos). © Daderot

Differs in rapid growth, photophilous, unpretentious to the soil, tolerates temperature drops down to -23 ºС. Used in single and group plantings. In culture since 1680.

Holm oak (Quercus ilex)

Homeland Mediterranean, Southern Europe, North Africa, Asia Minor.

Evergreen tree up to 25 m tall, with a smooth dark gray trunk and a dense, wide spreading crown. The shoots are grayish-felt, the leaves are small, up to 8 cm, highly variable in shape, leathery, shiny, dark green, yellowish or whitish-pubescent below. Acorns ripen in the second year.

We recommend storing freshly harvested acorns in trenches. Permissible period of dry storage - until the next spring. Acorns are stratified in moderately moist sand for 2-3 months at 2-5°C, then sown in greenhouses or ridges, where they germinate at 0-15°C for 20-30 days. Embedding depth s. 4 - 7 cm.

Holm oak (Quercus ilex). © propio

Grows fast, fairly shade tolerant, hardy, tolerates temperatures down to -20°C without damage. Drought tolerant. Grows on dry rocky slopes and any type of soil. It tolerates a haircut, durable. Valuable, beautiful breed for park construction in the south of Russia. Good in group, avenue and street plantings, in regular gardens - to create dense high hedges and high walls, for which its small-leaved forms are suitable. In culture since 1819of the year.

Chestnut oak (Quercus castaneifolia)

It grows wild in Armenia, the Caucasus and Northern Iran. Listed in the Red Book of the USSR. Protected in the Hyrkansky Reserve. Forms pure or with an admixture of other deciduous forests on the crests of ridges. Light-loving mesoxerophyte.

Tall, up to 30 m, a beautiful tree with a slender trunk, the bark of which remains smooth for a long time, with a wide tent-shaped crown and large leaves, resembling the leaves of a sowing chestnut, up to 18 cm long, with large, sharp, triangular teeth. From above, the leaves are dull, dark green, almost bare; finely pubescent below, greyish-white. Acorns up to 3 cm, 1/3 covered with a plush.

Chestnut oak (Quercus castaneifolia). © Mmparedes

Relatively fast growing, medium frost hardy, not drought tolerant enough. Good in alley, group and single plantings of parks and forest parks. Suitable for cultivation in the southwestern and southern parts of Russia, on the Black Sea coast. In culture since 1830.

Large-fruited oak (Quercus macrocarpa)

North American species, growing as a tree up to 30 m high, with a thick trunk and spreading, tent-shaped crown. The bark on the trunk is light brown, cracking. Leaves obovate, oblong, up to 25 cm long, deeply lobed; shiny, dark green above, whitish-green below, pubescent, in autumn they acquire a spectacular yellow-brown color. Acorns are oval, large, up to 5 cm, 1/3 covered by a cupule.

Seeds are stored for spring sowing in semi-moist sand in the basement. In autumn, the seeds are sown after harvesting and air drying. Germination of seeds is maintained until the spring of next year. Ground germination 80 - 85%. Seeding depth 5-6 cm.

Large-fruited oak (Quercus macrocarpa). © Daderot

Almost as fast as English oak; in terms of frost resistance, it is close to it and to red oak, but more moisture-loving than these species. Decorative, used in green building, like other species. In culture since 1826.

Oak diseases and pests

Plant wood diseases are the most dangerous. Infectious diseases that affect wood are divided into two groups. Non-rotten diseases include cancerous ulcers and tumors, vascular diseases of trunks and branches, necrosis of bark and sapwood. Diseases of this group affect the most important tissues of trunks and branches and, if strongly developed, lead to the drying out of trees. Cancer ulcers and tumors develop and spread slowly and are usually caused by fungi and bacteria. Vascular disease develops and spreads quickly and can lead to the drying up of trees in a few years or months. Necrosis of trunks and branches can also form extensive foci of desiccation. Their distribution is ensured by the ability of pathogens to accumulate a huge amount of infection in the dead tissues of affected trees. The causative agents of necrosis are also semi-parasitic imperfect and marsupial fungi, sometimes bacteria. Rot diseases include wood rot of branches and trunks, root and butt rot.

Gall midge

By autumn, yellowish or yellow-pink balls - galls - the size of a small cherry, often develop on oak leaves. They look like tiny apples of the correct spherical shape.

Galls - painful growth of leaf tissues. The gall midge insect, which looks like a very small fly, is to blame for their appearance. The gall midge pierces the skin of the leaf with a thin, sharp ovipositor and lays an egg there. Some time after that, a "ball" grows on the sheet. If such a ball is broken in late autumn, in the middle of it you can find a small white worm - a gall midge larva - or an already adult insect. In some years, oak leaves are literally dotted with galls - there are several of them on each leaf.

Gall on an oak leaf. © Fritz Geller-GrimmGall on oak. © RasbakGall on oak. © Saharadesertfox

Gauls are sometimes called ink nuts. This name is not accidental. Our ancestors at the time of Pushkin used them to make black ink. How to get ink in this way? It is necessary to prepare a decoction of nuts and add a solution of iron sulfate to it. Merging two weakly colored liquids, we get a completely black liquid. This chemical "focus" is easily explained. The gall contains many tannins, and they have the ability, when combined with iron salts, to give a thick black color. The same can be done with tea infusion (it also contains a lot of tannins). If a few drops of a yellowish solution of ferric chloride are added to a glass of weak tea, the liquid becomes completely black.

Pests of oak

Leaf-eating and stem pests, and fungal diseases are the most important factors that increase the drying of oak stands. Violation of the ecological balance of oak forest phytocenoses, especially in oak forest monocultures, leads to violations of the water regime of the territories, changes in light and temperature conditions in the plantation, and all together - to the formation of conditions more favorable for the development of pests and diseases.

Oak is damaged by a huge number of pests and diseases. Different authors give different figures on the number of pests and diseases that damage the oak. In the Tellerman forest area, 184 species of leaf pests were identified (Molchanov, 1975). Among the most common pests that damage the foliage, we should name: 5 types of silkworms, 5 types of cutworms, 6 types of moths, 8 types of moths, 8 types of sawflies, 2 types of leafworms, 11 types of gall wasps, 2 types of psyllids, 5 types of weevils, 2 types of Hermes, 2 species of aphids and 3 species of plant mites. Buds and flowers damage 12 species of gall wasps. Acorns are damaged by 2 species of codling moths, 3 species of weevils and 1 species of nutcracker. The trunk and branches damage 8 species of bark beetles, 7 species of longhorn beetles, 3 species of horntails, 2 species of woodworms, 1 species of flat-footed beetle, 3 species of borers, 1 species from the family of whetstones, 1 species of wood borers (Napalkov, 1953).

Sawfly caterpillars on oak leaves. © Beentree

In Europe, 542 species of pests damaging oak have been identified (Hrast Luznjak…, 1996). In total, 206 species of fungi were found, including zygomycetes - 3 species, mastigomycetes - 2 species, ascomycetes - 50 species, basidiomycetes - 43 species, deuteromycetes - 108 species. 1 virus was found - tobacco mosaic virus (TMV), 14 species of bacteria (Erwinia quercicola Geprges et Bad., Erwinia valachika Geprges et Bad., Pseudomonas quercus Schem, etc.). However, the influence of viruses and bacteria as causes of oak drying has not been clearly established (Ragazzi et al., 1995).

Healing power of oak

Young bark of branches and trunks, leaves and acorns of oak are used for treatment. The bark contains acids, resins, pectin, sugar. In acorns - protein and tannins, starch, fatty oil, sugar. The leaves contain tannins and dyes, pentosans.

Oak bark is used as an astringent, anti-inflammatory and wound healing agent. Mixed with other plants, it is used to treat gastritis, colitis, gastrointestinal bleeding, diseases of the liver and spleen. Inside give a cold infusion (1 teaspoon of crushed bark is infused in 2 glasses of cold water for 6-8 hours), 2-3 tablespoons 3-4 times a day.

A decoction of oak bark (1:10) is used for pharyngitis, tonsillitis, skin diseases, stomatitis. For the treatment of burns, a stronger decoction of the bark (1: 5) is used. For skin diseases, an ointment is also used - one part of the condensed decoction of the bark to four parts of lanolin.

A warm infusion of crushed oak acorns in red wine (25% tincture) in the form of compresses is used to treat hernia, and folk healers recommend water decoctions for burns, skin rashes, and excessive sweating of the feet. In addition, a nutritious coffee drink is prepared from acorns, which is consumed with milk and sugar.

For gastric bleeding, intestinal inflammation, poisoning with heavy metals, alkaloids, mushrooms, henbane, dope, food poisoning, a decoction of oak bark is used. For this purpose, 20 g of dry crushed raw materials are poured into 1 cup of hot water, boiled for half an hour, then filtered and the liquid volume is brought to the original boiled water. Take 2 tablespoons 3-4 times a day.

Infusion of oak acorns helps with diarrhea and enterocolitis. It is prepared as follows: 1 teaspoon of dry crushed raw materials is poured into 1 cup of boiling water and filtered after cooling. Take 1/2 cup 2-3 times a day.

For gargling with chronic tonsillitis, pharyngitis, inflammation of the gums and stomatitis, a decoction of oak bark is used. For urethritis and cystitis, a decoction of oak bark is taken 2 tablespoons 3-4 times a day. For the same purpose, an infusion of acorns is used in a similar dosage.

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