Samstag, 20. August 2011

Plant of the Day (August 20th, 2011) - Quercus robur L,


Today's “Plant of the Day” is the good old oak Quercus robur L. (in German known as “Stieleiche” and in English as “Pendunculate Oak”) from the Fagaceae family. In some literature, this species is also known as Quercus pendunculata L.
Q. robur - Habitus

It's normally a large tree, which can reach heights until 50 metres (16,4 feet). The young bark is greyish and smooth but with age, it becomes brown and deeply cracked. The tree trunk is highly branched, even in its lowers regions.

Q. robur - leaves

The leaves are between 5 and 15 cm long. They are following the alternate leaf-pattern and have a deep-green dorsal site, while their ventral site is a little bit brighter. The leaves are lobed or deeply sinuate. They are also completely bald and sitting directly at the shoot (sometimes, they have a very short stalk).

Q. robur - leaves and young acorns

The flowers are unassuming catkins, which are found clustered at the end of the shoots. The fruits are nuts: the so called acorns, which mature in autumn. They are sitting in a small cup, which is called the cupule. The cupule have a long, pendunculating stalk, which also gave the species is name.

Q. robur - young tree

At the first sight, Q. robur can easily be confused with Quercus petraea (Mattuschka) Liebl.. (“Traubeneiche” in German and “Durmast oak” in English). But this species has stalked leaves, while the leaves of Q. robur are sitting. The fruits of Q. petraea have also no stalk.

Q. robur - young plant

Q. robur is common throughout Europe (except Iberian peninsula, Scandinavia, South Greece and the high alpine). It likes nutrient-rich and deep soils but can also be found on alternate wet soils (e. g. gley soils). This plant also needs bright places to grow and cannot grow at shady locations. Because of this, Q. robur was repressed by the fast growing beech (Fagus sylvatica L.), which shaded its environment. So today, you found natural oak forest only on sites, where the beech cannot grow (e. g. floodplains or dry, nutrient-poor soils). The tree also benefits from anthropogenic influence. So, it can also be found in parks, clearings or man-made forests

Q. robur - acorn and young root (the acorn
was dig by a squirrel and the plant came out of
 the acorn)

The wood of Q. robur is endurable and it's easy to work with it. So, it's used as timber and furniture-wood, but also to make wine barrels. In past, the acorns were also an excellent feed for pigs, because of their high content of starch. So in the fall, the pigs were driven into the forest by the farmers to eat.

Q. robur - cotyledon (inside the acorn)

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