That smell we love so much, that has even been bottled into a scent is the distress call of your freshly cut lawn. It is the release of a chemical defense and self administered first aid from the hundreds of thousands of injuries you just inflicted with your precious lawnmower.
Plants release a whole number of volatile organic compounds called GLV’s (Green leaf volatiles) normally. Whenever a leafy plant is injured it starts to release them in high numbers with some of the compounds stimulating the grown of new cells which help the wounds heal quickly. Some compounds will help the plant by acting as an antibiotic or antifungal aid.
More interestingly it can be used as a distress signal by plants to warn other plants of incoming danger giving them time to put up a defense. An example of this is when giraffes eat acacia trees. Giraffes have developed the understanding that if they approach an acacia grove from down-wind then, as they eat the acacia, the distress signal sent will blow away rather than towards the other trees. This allows the giraffes to continue munching their way through the other trees. This distress signal allows the acacia tree to release a chemical into the leaves that make them taste foul to the giraffe.
Geocoris punctipes
Scientists found, in one study, that the saliva of certain caterpillars reacts with the compounds released by coyote tobacco plants to make them attractive to the Geocoris punctipes AKA “big-eyed bugs” that regularly eat the caterpillars.
There may be a high cost to that wonderful smell of freshly cut grass, though. The compounds released are precursors to ozone formation, according to researchers, and can contribute to the formation of photochemical smog in urban areas.
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.
The comet ATLAS-Y4 will be closest to Earth on May 23, 2020.
On December 28, 2019, a new comet was detected. When it was first observed, the comet was quite faint. But since then, it has been brightening every day as it makes its way closer to the Sun.
ATLAS Y4
Astronomers believe that ATLAS is about to grace our skies with perhaps one of the brightest light shows that we’ve seen in a while.
The comet’s name is an acronym for Asteroid Terrestrial-impact Last Alert System (ATLAS), a robotic astronomical survey system based in Hawaii designed to detect smaller near-Earth objects a few weeks to a few days before their closest approach.
ATLAS’s Path
As comets travel closer to the Sun, they increase in brightness as the heat from the star causes them to burn. ATLAS is headed toward the Sun, and on May 31, 2020, it will be at its closest 23.5 million miles to the star, that’s closer than planet Mercury is to the Sun.
The comet ATLAS will be closest to Earth on May 23, 2020.
Comets are at risk of breaking apart as they draw nearer to the Sun, running out of gas and disintegrating from the heat of the star. However, if it does survive the journey, ATLAS will hit its peak brightness by the end of May, where it could possibly grow brighter than Venus and become visible to the naked eye.
ATLAS from Hubble
Perhaps the most opportune day to view comet ATLAS would be on May 22 as it will coincide with the new moon. Therefore, it provides the perfect opportunity to view other objects in the sky without the disrupting light of the Moon.
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.
