Tree a Week: Oak

Following on from my last post about Patagonia’s Treeline and Wohlleben’s ‘The Hidden Life of Trees’, this will be the first of a series of post on trees. I’ve always wanted to learn more about trees – how to identify them, it’s uses, a little bit of history and characteristics – and now that I have plenty of time, I thought it would be great to learn about a tree a week. And thought it might be valuable to share those learning here – a short condensed version of my research. So starting with Oak this week.

Characteristics and Fun Facts

  • Oaks are in the genus Quercus of the beech family
  • There are 600 species of oak, of which at least 78 is endangered
  • Most species of oak are deciduous with couple of evergreen
  • They can be found in temperate, Mediterranean and tropical regions in Americas, Europe, Asia and North Africa
  • Oaks start producing acorns from ages 20 to 50
  • Pechanga Great Oak Tree is reported to be the oldest at over 2000 years – it started it’s life around the same time as Jesus

Most oak species live for over 200 years with some, such as Bowthorpe Oak above, living well over a 1000 years.

The mature trees shed varying numbers of acorns annually. Scientists suggest that shedding excess numbers allows the oaks to satiate nut gathering species, improving the chances of germination. Every four to ten years, certain oak populations will synchronize (probably through fungal network communication) to produce almost no acorns at all, only to rain them down excessively the following year, known as a “mast” year. The year preceding the mast year is thought to starve off the mammal populations feeding on the supply, thereby increasing the effectiveness of the overproduction in the mast year that follows. This is necessary to the survival of any given oak species, as only one in 10,000 acorns results in an eventual tree.


The wood and leaves are highly resistant to insect and fungal attack because of high tannin content but still has multiple diseases that affect the population. Acorns high in tanning are poisonous to most livestock such as cattle, sheep, horses and goats except for pigs and ducks. Oak was used for construction of ships in Europe for centuries, and is still commonly used in furniture making, timber frame houses and barrels for wine and spirits.


Lobed leaves are leaves that have rounded or pointed knobs extending out from the center line. While a few oaks do not have lobes, all of the leaves are generally symmetrical around a clear median line. For more detail on identifying oak leaves click here.

Small, scaly bark. Bark on oak trees is variable, but it is generally made up of small, hard, and scaly bits of bark. This is unlike the large, flaky chunks of pines or the wallpaper-like bark on birch trees, and is much more cracked and grooved.

In comparison with other types of barks

Acorn Cap Whistle

You can use the cap of an acorn as a whistle. It’s super easy and can give off a pretty loud sound. Choose a well ridged large acorn cap for the best sound. If you’re interested, this page explains it really well.

Eating Acorn

From Native Americans to Japanese hunter gatherers, where ever humans settled near oak forests, we seemed to have figured out how to eat them. The main process is leaching the tanning (which gives a felty dry feeling in your mouth) by either

  1. Bringing a pot of peeled acorn in water to a boil, drain the brown liquid, then repeat 4 to 5 times until the water runs clear
  2. Or grind the acorns into a powder and soak in water in a fridge overnight. Discard water containing the tanning and refill with fresh water daily for a week or two.

The hunter gatherers would probably have used a basket submerged in a stream for a couple of weeks to leach the tanning. But I would avoid doing this if you know there are conventional farming going on upstream as risk of ingesting glyphosate should be avoided at all costs. To know more about glyphosate and its sister compounds’ mind blowing effect on our health, check this video out.

The best guide to processing and eating acorns that I found was this page. More detail on cold leaching here. And tasty looking recipes using acorns here.

If you want to know more about trees, particularly in the context of creating a forest garden, this book by Martin Crawford is worth checking out. It’s pretty affordable for a thick comprehensive book full of quality photographs and a lifetime’s worth of research and expertise from a man who has been at the forefront of forest gardening for the last 20 years.

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