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Quercus macrocarpa (Bur oak)

Bur oak (Quercus macrocarpa ) is originally from northeastern America and is considered to be a “settler”. It now grows in Alaska and Canada as well as in the southern United States.

It was first mentioned botanically in 1811.

It is very heat and drought resistant and as a candidate tree against the consequences of global warming in urban areas of Europe (occurs there so far still very rarely).

The burr oak grows up to 50 meters high and reaches trunk girths of up to 3.5 meters. Their growth is relatively slow (30 cm). It is interesting to note that the more northerly the acorns occur, the smaller they become. If they reach diameters of up to 6 cm in southern climes, they are often conspicuously small in the north. The name “Macrocarpa” (= large fruit) refers to the sometimes huge acorns.

The tannic acid content of acorns is relatively low. The smaller the acorns, the sweeter they taste. Thus, the burr oak is one of the few acorns that are edible. They can be easily fried and eaten and are considered a delicacy in some areas of the United States.

The taproot of the Bur oak is considered fast growing and reaches depths of up to 1.5 meters after only two years. The oak species lives up to 400 years. The leaves can grow very large (15 cm long and 5 cm wide) and have a leathery appearance. Due to its very thick bark, this oak species is even (somewhat) resistant to forest fire.

Optimal for the Bur oak are weakly acidic soils. The tree is also considered suitable for urban climates, but grows very sprawling in width. Sunny sites this tree, like most oak species, likes very much, shade sites are not suitable. The tree is sometimes even described as very resistant to the effects of road salt, see e.g. https://www.angelbachtal.de/dr/bur-eiche-grossfruchtigeeiche.

The wood is thick, tough, heavy and durable. It is one of the most valuable barrel and furniture woods. In addition, it is also used in construction for flooring and the like.

You can buy the acorns in our store.

Quercus Macrocarpa Source: https://en.wikipedia.org/wiki/Quercus_macrocarpa#/media/File:Big_Tree_with_spring_picnic.jpg

Acorns City climate suitable Unkategorisiert

DocKalle Quercus petraea

Quercus petraea (Sessile Oak, Winter Oak)

Quercus petraea (the Sessile Oak, also known as the Winter Oak) reaches growth heights of up to 40 meters and trunk girths of up to 2 meters. It can live up to 1000 years.

Acorns ripen from September to October and grow up to 2.5 cm long. They grow in a kind of “cluster” (hence the name sessile oak). The bark of this oak species is smooth when young. A thick, deeply longitudinally fissured, gray-brown bark develops with age.

This species of oak is often found in slightly mountainous areas, it seems to especially like sunny slopes. It is found in many European countries (from Italy to Scandinavia). It is found especially on stony and clay soils; likewise on nutrient-poor soils. However, it does not like waterlogging and too much moisture. It is considered storm-resistant and can penetrate soil layers that are poor in oxygen. In sub-Mediterranean climates, it forms mixed forests with downy oak and Turkey oak. Evidence shows that it has been present in Europe for about 10 million years.

Quercus petraea is relatively drought resistant and is more likely to survive climate warming than the English oak. It is considered to be very heat-loving. It is also considered (in Europe) to be tolerant of heat, drought, emissions and salt. For these reasons, it is also often planted in urban areas. Sessile oaks sprout very early in the year and their leaves can still be found late in the season.

The acorns have a high starch content (almost 40%) but are very bitter without specific water treatment (flushing). However, in principle, they are suitable for an acorn coffee.

Originally, they were used especially for fattening pigs (even before the use of wood). The wood is readily used for construction activities or even wine barrels. In Central Europe, the sessile oak provides a home for up to 500 insect species.

In medicine, the sessile oak is widely used because it is very rich in tannins. Pieces of bark used to be placed on wounds and injuries because they prevent inflammation and stop bleeding. Oak tea of this type is also used against liver disorders and diarrhea.

About the sessile oak see also this link

You can buy acorns of sessile oak in our store.

Acorns City climate suitable Climate Warming Resistant Unkategorisiert

DocKalle Quercus rubra, Red oak

Red oak (Quercus rubra)

The red oak (Quercus rubra) is native to the USA, where it is the state tree of the state of New Jersey.

The red oak can grow up to 35 meters.
Untypically for oaks, the bark is initially smooth when the tree is young and only becomes rough and “barky” with age.
The leaves turn to a rich red (reddish brown) in the fall. For the latter reason, the red oak is also often found in parks.
It begins to fructify (form acorns) at about age 25.
The acorns have a two-year development period. This feature is beneficial against pest infestation, as pests are not adapted to the two-year development period of acorns.
The fruits remain very small in the first year and ripen only in the second year. An acorn is about 2×2 centimeters, egg-shaped and only partially surrounded by a fruit cup.

Originally it comes from the eastern part of the USA, but has been used in Europe since the 17th century.
It is considered to be assertive and relatively climate robust. It is considered relatively drought tolerant and storm resistant due to its taproot system.

Their alien origin is neglected in trade-offs against the benefits of increased timber harvest.
“Other than general conservation discomfort with guest tree species, red oak is seen as unproblematic in most cases. Undesirable spread in mature coppice and border sites, especially in rocky areas where native rocky flora may be displaced. Because it is less accepted than native oaks by specialized and phytophagous insects, it establishes species-poor biocenoses (Source:
https://www.lw-heute.de/je-waermer-desto-regen-braucht-roteiche).

In Germany, a study exists comparing species diversity on red oak (Quercus Rubra) and English oak (Gossner 2004):

* Compared to the English oak, the red oak crown monocultures are poor in individuals and species.
* The differences are more pronounced in the pure stock.
* Red oak has significantly lower numbers of individuals and species of endangered insect species. Nevertheless, the red oak is not an “ecological desert”.
(cf. also https://www.lwf.bayern.de/biodiversitaet/biologische-vielfalt/230750/index.php).

You can buy acorns of red oak in our store.

Acorns City climate suitable Unkategorisiert

DocKalle English oak, Quercus robur

Lots of fresh acorns of English oak (Quercus robur)

Currently is the time when the acorns of the English oak (Quercus robur) fall. Cheerfully they are collected here.
The English oak is kinderleit to identify. The acorns hang (sometimes in multiples) on a long stalk. The leaves of the English oak sit close to the branch. The acorns are germinable only for a short time (about 6 months). The English Oak is also called “German Oak” or “English Oak”.
English oak can grow up to 40 meters high and live 1000 years. Individual trees were even up to 1400 years old.
Only from an age of about 60 years (!) it is able to develop germinable acorns.
Quercus robur is considered to be very storm resistant. Their taproots can also tap very strong compacted roots.

The English oak is found throughout Central Europe, including parts of Scandinavia, Italy, Greece and Portugal. Nevertheless, the English oak is sometimes considered “problematic” in terms of climate warming (low tolerance to drought stress), see this link . However, this is not a unanimous opinion. There are even various positions that the English oak can be called the winner of climate warming in the medium term.

English oak is considered very frost resistant and grows even in waterlogged areas. It provides food and habitat for many species of insects and their larvae, and provides pollen for bees in May. The fruits are an important food source for many species of birds and mammals. For example, the jay or squirrel spreads the pedunculate oak by creating food depots.

Quercus robur as food

After treatment (sponging) of the bitter substances, the acorns can be processed into “flour”. For this purpose it is necessary to soak the acorns in water for several days and to change it again and again. After about 4-5 water retention (2-3 days each), the acorns can be processed into flour. They contain a high proportion of starch (at 40%). However, the flour should be combined with classic flour variations (for example, with wheat flour).
It is known that even Stone Age people collected and stored acorns on a large scale – this often ensured survival in winter.
Tannins and tannin make digestion difficult, yet the acorns of the English oak served in famines and during war years due to their starch, oil, sugar and protein.
as food, by “stretching” cereal flour with acorn flour. In Russia during World War 1, acorn flour was used to bake an officially tested “hunger bread”.

Fresh, germinable acorns of English oak can be found in our store.