I’m not sure how common this is in the uk but it’s something I feel is massively underused and is in danger of being lost from our history completely ,
Cambium or ‘bast ‘ is the growing tissue of a tree which adds new growth to the circumference of a tree it contains carbs in the form of sugars ,
I find it hard to group cambium to a food group … It can be a sweet but also a steamed or roasted like veg or dried and pounded into flour in any instance it is a massive wild resource.
I have no doubt at all that our ancestors would of used this to its full potential , although I have found no standing reference to it within uk history but you don’t have to look far to find massive references to its importance to hunter gatherer communities in fact in communities in America were still harvesting and processing well into the 1900s and was such an important part of their diet that their name in the Mohawk indian language means “tree eaters and cambium collection was a big and important part of the food year it is this that concretes my belief that hunter gatherer communities in the uk would have taken part in similar exercises .
So firstly I would like to cover ethics surrounding the collecting cambium in modern times ,
Traditionally trees were harvested by cutting a strip into the tree around three inches wide and 30inches in length and by doing such the tree is able to repair itself and no lasting damage is done ,
We have to be realistic we simply do not have the freedom to go around scaring trees on public land so we have to find a viable alternative .
It is actually quite easy to source ,
Most large woodlands have a management structure in place which includes the felling of trees and with a respectful approach you will find that if you seek permission you will be pointed in the right direction I have asked in two separate areas and the woods management was happy to show me a area where suitable trees that were due to be worked and found it fascinating that I was even attempting harvesting , and in my opinion if you are willing to put the effort in to even consider this then putting the effort in to gain permission is a small hurdle as in most cases the trees that are offered are due to be felled and you can be less restricted about amounts of cambium you collect.
And I also would hope that anyone who has a liking for wild foods would have a equal respect for the countryside and wouldn’t be randomly scaring trees .
So next is timing and this is where you have to work for your return as the cambium is only prime and palatable for maybe three weeks of the year , this is normally around summer solstice but varies not only due to weather but location , trees on woodland margins in more sunlight will be ready before trees is dense woodland .
I have only successfully harvested from three types of tree that I found palatable the first was maple but was more luck as we do not seem to have large maple woodlands so I tend to be limited to two types of pine Pinus contorta the shore pine and Sitka spruce ,Picea sitchensis both of which give sweet and enjoyable bast I have tried ash but it was far from pleasant in taste but I have read that there are records of up to filthy species of tree being used in this way across the United States .
The time that you want to harvest the bast is when it is new and supple this tends to coincide with the falling of the sap and pollen release from the cone ,
Not every tree produces nice edible cambium and testing trees to find a good tree is needed, we do this by cutting a v-grove at chest height point upwards then try to peel the bark downwards if the bark does not peel the tree is not suitable to harvest if it does peel it down about twelve inches leaving it attached and scrape a small amount and simply try it , a good tree will taste sweet and be soft as I’ve said just because the tree has good cambium does not mean it is tasty and if the cambium is sour in taste simply replace the outer bark .
The best cambium is from chest height down to the base of the tree and can be as thick as 5-8 mm good cambium does not come from branches .
Choosing your tree is simple only harvest from trees that you can reach around with both hands at this size the tree is approximately forty years in age and the outer bark will be workable after this the bark becomes far to thick to peel .
A visual markers to be aware of other than pollen is what I call stretch marks these are shown as the tree bulges with new cambium and is shown as light joints in the old bark these are a good evidence that the tree is producing a good amount of cambium .
When you have found a good tree placing your grove is equally important as the cambium grows thicker on the south facing side of the tree and sweeter in damp conditions so ideally your looking for a south facing riverside slope .
Harvesting is also simple we are not cutting large chunks from the tree we are scraping thin lengths from each section (noodles ) until you go through to the inner wood this is obvious as it changes in consistency a great tool is a crook knife or a sharpened paint scraper these will be see-through.
It’s worth mentioning that it will spoil quickly so suitable containers are needed , I prefer harvesting at the dawn of a day so the sun hasn’t warmed the sap as it can become a messy job .
Within woodland living a single tree would be chosen and it would be girdled this means to be stripped to the full circumference this means the tree will defiantly die but it also means the stripping will cause the tree to produce sap around the wound and in time the tree would absorb the sap this creates what we call ‘fat wood ‘this is made into kindling and used as fire starters throughout the damper months and excess pitch is collected for gum
Fresh cambium as a raw treat needs to be eaten within 24 hrs after that you need to decide on your next step as the taste changes to sour quickly .
The most popular by far seems to be to dry and grind into a flour and its a perfectly reasonable process as it drys very quickly on a jerky rack in the sun it can dry within hours it can then be ground using your preferred method a coffee grinder works well, a point worth mentioning is that Cambium does not contain gluten so will not bind without adding artificial gluten or simply by mixing it with other flour a 50/50 mix seems to work well for baking ,
The next use is a process used by the first peoples in the upper states of America .
The cambium was collected by entire communities and was regarded as a spring treat , collected in quantities taken back to camp and mashed with water and moulded into cakes wrapped in leaves and then placed in underground ovens much like a hangie it was with a lot of research that I discovered that the purpose was not to bake the cakes but steam them this was done by placing half round pieces of the outer bark on hot rocks and putting the cakes on top to steam,for about an hour then dried on a rack for a day then the cakes are then cold smoked for about a week to preserve the cake and then it is used throughout the year.
The process fascinated me and was simple enough to recreate and I was pleasantly surprised by the result as the sweet taste was preserved .
It is also easy to recreate the process at home with a simple steamer and smoker .
To use the cambium after the process it is boiled and then roasted much like potatoes and has a really pleasant taste .