Knowing how to identify oak wood and oak trees is not as difficult as it may initially seem. There are a number of physical and visual signifiers that easily separate oak from other species. There are two main species of European Oak: Pedunculate Oak (Quercus robur), also known as English Oak, and Sessile Oak (Quercus petraea).
Both being of the Quercus genus, they share many physical characteristics but still have a number of specific differences. Realistically, this makes little difference in their use as timber as English Oak wood and Sessile Oak wood are so similar in strength and durability.
How to identify oak trees
1. Shape and Profile
Used in many company logos, oak trees have a distinctive silhouette that is easily recognised. Oak trees have a wide, rounded canopy, usually taking up two thirds of the overall height of the tree compared to the trunk. The trees themselves, once matured, are extremely tall with notably thick trunks. The largest of these in Britain, known as the Major Oak, stands in Sherwood Forest and has a trunk with a girth of 33 feet.
Oak tree branch structure is particularly distinctive. The branches of the canopy are thick and kinked with no straight leader as branches grow out in an alternating pattern. There are no opposing growths as buds are arranged in a spiral pattern, producing branches in random directions.
Winter twigs have a smooth silvery brown bark with clusters of buds at the tip and individual buds arranged in a spiral along the length. These buds have small overlapping dark brown leaves, giving them a scaly appearance.
In young trees the oak bark pattern has irregular shallow fissures, as if the surface layer has split then healed, with a silvery grey brown colour. As the tree ages, the bark thickens and takes on a darker hue, though remaining grey. The fissures grow deeper, giving the trunk a rough, almost scaled appearance. Oak bark often has a layer of lichen, one of many other species it supports, lightening its colour.
Along with its acorns, the leaves are probably one of the most recognisable features of an oak tree. Two major British conservation organisations, the Woodland Trust and The National Trust have it as their emblem. It regularly crops up in English heraldry and military decoration, showing the status of oak in British culture and history. The leaves themselves are longer than wide with a wavy outline of lobes and sinuses (curved projections with indentations between).
There are between five and seven lobes to each side and the lobes are far more pronounced and curved in pedunculate oak. Sessile oak leaves often have fine hairs on the underside, particularly along the midrib. Leaves grow in a spiral pattern along the twigs and on sessile oak leaves have a very short stalk at their base. Over the year, their colour changes from deep green to a vivid reddish brown and dark brown in winter. Oak leaves are slow to decay, and often remain attached until new leaves grow in the spring.
4. Acorns and Flowers
Do oak trees have flowers? Surprisingly the flowers of an oak tree are obvious if you know where to look at the right time of the year. Oak trees are monoecious, possessing male and female flowers on the same plant. The Male flowers are small and light yellowish-green and hang down on drooping catkins. As oak trees are wind pollinated, this allows the wind to blow through the flowers and carry their pollen away. This happens during April and May and the male flowers are most obvious at this time of year.
In sessile oaks, small red female flowers are found in the leaf axils where the leaf meets the tree branch. In pedunculate oaks, the female flowers sit at the end of new shoots call peduncles that will eventually become acorn stalks. Once the female flowers are fertilised, they develop into acorns during the Autumn months. These consist of a nut and cupule, resembling a tiny egg and eggcup and are familiar to almost everyone. Sessile oak acorns have extremely short stalks and grow in clusters on the twigs, whereas pedunculate acorns grow singly on long stalks.
Identifying Oak Wood
When renovating furniture or the structure of a timber framed building, it is important to be able to identify the wood used. Existing timbers may need to be replaced and using a softwood to replace load carrying hardwood could be disastrous. For furniture, matching replacement parts to the existing timber will conceal the repairs and give a pleasing, consistent end result.
As it ages, oak reacts in different ways to other hardwoods, resulting in obvious splits and shakes and colour change. As this is part of its appeal and charm, this will need to be complemented or the result will be mismatched and ugly.
As a hardwood, oak is naturally dense and consequently heavier than many other types of timber. Each type of wood used in construction or furniture has a particular weight. If a place has been removed for replacement it can be weighed and the weight for its size measured. If not, check if a small sample can be removed without being visible or weakening the structure and this can be weighed. This then be compared to online databases or other reference works to make sure it is oak.
If you know the history of the furniture or building, there may be clues to the material used in its construction. Even knowing the general age can be useful as it will be easy to research building techniques and commonly used materials. Although this may not give a definite answer, in some cases it could. Using reclaimed replacement timber of a similar age guarantees a good match.
3. Colour and Grain
Oak ages in vey predictable ways and the colour of the timber could be a strong indicator. As it ages, the timber ‘silvers’ to give a look unlike any other material. Oak ,especially in longer pieces such as beams, has a distinctive regular grain pattern. It also has very few knots or other imperfections, making it easy to identify In furniture, the use of pippy or waney edge oak will be obvious just from its appearance.
Old oak timbers will have obvious splits, or ‘shakes’ running the length of the grain. Again, these are seen as a desirable side effect of the seasoning process. While they are not unique to oak, they are unusual in other timber and form in quite a distinct way. Due to the hardness and grain texture of oak, it is rare to find oak that is sanded completely smooth. With oak furniture, simply running your hand across the wood can allow you to feel the telltale ridged texture.
Hardwoods Group are industry leading suppliers of European Oak. We offer wholesale timber, pre-made oak building frames and bespoke commissions. Whatever your oak needs, contact us, we will be happy to help.
A History Of Oak
Properties Of Oak Wood
Top 5 Beautiful Heritage Oak Buildings