Petrichor is the name of that smell when the summer rains fall after a hot day. What’s it called? Why does it smell?
Petrichor is the earthy scent produced when rain falls on dry soil. The word is constructed from Greek petra, “rock”, or petros, “stone”, and īchōr, the fluid that supposedly flowed in the veins of the gods. I think “Petrichor is better sounding than “rocky god blood”.
What is it?
Well, it is slightly more complicated than might be first thought.
The smell is the aeration of a combination of an oil that is produced by plants during long periods of dry weather that then settles into clay based soils and rocks. When the rain falls it gets lifted into the air and combines with another compound that is a metabolic (breaking down of compounds) by-product of Actinobacteria (see section below) which is released as the soil becomes wet.
So in short it is a mixture of plant oils and a by-product of bacteria that build up during as dry spell give us that distinctive scent from summer rain that invokes so many positive thoughts and childhood memories.
According to research from MIT University heavy rain actually produces fewer aerosols than a light or medium rainfall, according to their findings. So that might be why petrichor is associated with the moments after a drizzle.
Actinobacteria exist as either dormant spores or actively growing mycelium with filaments called hyphae. Most of these free-living organisms look like strands of hair or spaghetti under a microscope. Some are spherical in shape, others are branched, and many have knobby or hair-like projections.
When we talk about fungi we more often than not, like so many plants and trees, are actually referring to the fruiting body of the fungi. That is to say, that the mushroom looking thing we stumble upon is actually the “flower” of the fungus. The rest of the fungus, which we cal mycelium is actually in the earth or within the host like trees, for example.
The mycelium is a network of filaments, or fibre like structures, that weave their way into and around the soil or host soaking up nutrients and moisture that it needs to survive. When the conditions are right, more often than not after some rain, the mycelium send out its fruiting body to eventually release spores as its way of reproduction. Some fruiting bodies only last a few days where others can live for 40 or 50 years, such as some members of the family of bracket fungi.
Uses
Traditional uses of this fungi was really the inspiration for this post. I have been processing amadou recently and thought you guys might like to know more about it.
Amadou is also known as mushroom leather and is used to create a very fine tinder for primitive and prehistoric methods of fire lighting. It’s valuable to people in the bushcraft community because it can catch the smallest and coldest of sparks from iron pyrite or a steel striker.
Tinder fungus such as amadou has been used as tinder since at least the time of Ötzi. Ötzi, also called the Iceman, is the well-preserved natural mummy of a man who lived between 3400 and 3100 BCE. The mummy was found in September 1991 in the Ötztal Alps, hence the nickname “Ötzi”. He is Europe’s oldest known natural human mummy, and has offered an unprecedented view of Copper Age (Chalcolithic) Europeans. He was found to be carrying Amadou in his pocket. The kit he carried featured pieces of over a dozen different plants, in addition to flint and pyrite for creating sparks. Our prehistoric fire lighting kits, similar to what Ötzi carried, can be found here.[efn_note]Wikipedia entry on Otzi[/efn_note]
It is also valuable because the processing takes effort and time. The bracket is made up of three layers:
The “cuticle” is the upper surface and can be very hard and difficult to remove.
The “amadou” layer which is the jam in the sandwich.
The “pores” which are tube like structures that release the spores, a process called sporulation, during the reproductive cycle.
The removal of these two outer parts (1 & 3) is time consuming and difficult. The amadou layer then needs to be boiled for anything up to 3 days and then pummelled gently to separate the fibres and soften the “leather” this process puts a lot of people off processing it and makes it an expensive process. Some people use the boiled liquid as a tonic for an upset stomach, however it has a strong purgative effect and should be avoided.
Traditionally the fungus Forms formentarius is used to make amadou and is still considered the best, it does however grow mainly in colder northern regions and primarily on silver birch trees. Nearly all bracket fungi can be made into tinder fungus and, here in the south of England, I favour the Ganoderma australe variety, it makes a tougher leather but still catches the smallest of sparks. It is the variety we sell most of in our online shop. It also has the providence of being locally sourced and locally produced, rather than importing from further afield.
Harvesting
Removing a bracket fungi from a tree does not harm the tree in any way, the tree is already dead or dying. As previously mentioned, the bracket, is the fruiting body of the mycelium network that has already infected and started to kill the tree, causing heart wood rot. I always leave a couple of brackets on the tree so I can come back the following years to collect more. Generally speaking we don’t want the older brackets anyway as they get older they have less amadou layer and they are tougher to break into.
I hope this has given you some insight into a few uses for a bracket fungus and if you fancy giving it a go you can get your special prehistoric or primitive fire lighting kits here.
The candelabra of suburban avenues and the source of childhood conkers,as well as the sticky buds of biology/botany lessons, this tree, which is native to the Balkans, is well integrated into British life.
Horse-chestnut
It became popular here in the 17th century where it was planted throughout Europe along avenues, churchyards and parks.
It is our only tree with large, radiating, compound leaves. It’s name perhaps comes from Turkey where, in 16th Century where it was said that they used to feed the nuts to coughing horses, but horses don’t like them, cattle do! Another theory of the origin of its name is that the leaf scars on twigs resemble horseshoes, either way, both are plusable.
Nuts are supposed to grow into seedlings in Britain but it is unusual to find one that has not been planted on purpose.
Uses
Horse – chestnut blossom
In herbal medicine the horse chestnut is used to treat varicose veins and hemorrhoids.
For centuries the large shiny nuts that are enclosed in spikey cases are used by british children to play a game called conkers where they are attached to string and hit against each other, the looser being the one with the broken nut.
There’s hearsay that if you place conkers around your house it will keep spiders away, but there’s no scientific proof that this is the case.
The Victorians wrote recipes for making conker flour. The seeds were shelled, ground and then leached to remove bitter flavours. It’s not a common practise these days and if consumed in excessive quantities conkers are mildly poisonous.[efn_note]Woodland Trust[/efn_note]
Hybrid
They can grow up to 40m in height and live for 300 years. They have leaves which are large green and palmate (finger like) with 5-7 leaflets. The flowers are beautiful towers of pink or white flowers. which turn into green spiky fruits.
The flowers provide a rich source of nectar and pollen for insects, particularly bees. Caterpillars of the triangle moth feed on its leaves, as does the horse chestnut leaf-miner moth whose caterpillars provide food for blue tits. Deer and other mammals eat the conkers.
Hybrid Horse Chestnut
Aesculus × carnea, or red horse-chestnut, is an artificial hybrid between a red buckeye and a horse chestnut. The origin of the tree is not known, but it probably first appeared in Germany before 1820. The hybrid is a medium-size tree to 20–25 m tall, halfway between the each of the parent species in most respects, but inheriting the red flower color from the red buckeye. It is a popular tree in large gardens and parks.
Known to all, even the hardest non-botanists, the daisy is the romance of poets and writers from Geoffrey Chaucer to Thomas Hardy.
A Native wildflower, the daisy can be found everywhere from mountain grasslands, costal cliff-tops and sand-dunes, on hedge banks and, especially, lawns and other grasslands.
It flowers from February to December, peaking in late spring, including all through mild winters.
As you can see from my time-lapse video of a daisy it’s flowers open and close at dawn and dusk and on overcast, dull or wet days (just like the dandelion –see article on dandelions).
It has historically been known as a valued herb for healing wounds. We shall revisit the works of Nicholas Culpeper M.D. from the 17th Century.
Daisy
“ The leaves, and sometimes the roots are used. They are among the traumatic and vulnerably herbs, being used in wound-drinks, and are accounted good to dissolve congealed and coagulated blood. They also help pleurisy and peripneumonia. In the king’s-evil the decoction given inwardly and a cataplasm of the leaves applied outwardly, are esteemed by some. An infusion boiled in asses’ milk is effectual in consumption of the lungs”.
More modern uses are crushing the leaves and applying to wounds which will still work to soothe and help healing. In some places it is still known as ‘bruisewort’ In a remedy for lumps and swellings as a result of injury, and also for chronic skin diseases due to impure blood, such as boils.
All in all the often overlooked garden weed is powerful as a medicinal herb both today and through history.
