Hair frost is a very interesting phenomenon, which I came across for the first time this year in December.

Hair ice forms on decaying broadleaf wood during calm, freezing weather. It gets its name from its hair-like structure, created by ice filaments only a hundredth of a millimetre thick. They are therefore about the same thickness as human hair. These “hairs” can grow surprisingly long if the place is sheltered. In such conditions, they even become curly, believe it or not.

Hair ice does not form due to frost alone; it also requires the help of a fungus called Exidiopsis effusa. When decaying wood freezes, internal pressure builds up, forcing excess moisture out through the fungus’s fine filaments. As this moisture is pushed to the surface of the wood, it freezes into hair-like formations.

What is particularly interesting is that only about ten years ago was the role of the fungus Exidiopsis effusa in the formation of hair ice fully understood. This makes one wonder how many things fungi influence behind the scenes, without us even realizing it yet.

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This weird fungus has many descriptive names: strawberries and cream, the bleeding tooth fungus, the red-juice tooth and the Devil’s tooth. These names comes from it’s behaviour. In damp conditions, it exudes bright red droplets on its surface.

It forms ectomycorrhizal relationships with conifer roots. It’s found mainly in North America and Europe. It’s not poisonous, but not edible either — it tastes very bitter. It has been used in natural dyeing.

This fungus produces atromentin, a compound with blood-thinning and antibacterial properties. Its cap is young and velvety, with a pale brown flesh and brown spore print, and the underside is covered in short, dense spines.

When I first saw this fungus a few years ago, I was truly amazed. I had never seen anything so extraordinary. Often this fungus is pale or brown, without those droplets. Then it is easily overlooked. So you have probably come across this fungus too, even if you haven’t seen it in this dripping outfit.

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This fungus belongs to the jelly fungi group and grows on tree trunks, decaying the wood. It has a strikingly bright orange color and comes to life with the rain, drying and disappearing again when the weather turns dry. It can be found throughout the year, and you can often spot them shivering on branches even from beneath the snow.

It is edible, though rather tasteless.

Species of this genus have been found to stimulate the immune system, reduce inflammation, lower blood sugar and cholesterol levels, protect the liver, and help prevent allergies.

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The moon jellyfish is the only jellyfish found in Finnish waters. Although it is a native species, it still feels almost tropically mysterious to us northern dwellers.

We see them regularly, but a few years ago we had an amazing encounter while vacationing in Hanko, the southernmost town in Finland. There were so many moon jellyfish. My son was thrilled — he lifted them into his hand. I let him catch one in a jar to take a closer look.

They eventually drift ashore and die. A new generation waits as larvae on the seabed for spring and the warming of the waters.

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I met this leopard slug during an evening walk. It was dark, but I couldn’t not notice that large slug. Leopard slugs are active at night. It eats decaying plant matter. They also eat other slugs and carrion.

It spread to Finland in the late 1800s and is found in old gardens, being nonetheless very rare. A single slug can live up to three years. It can grow to over 20 centimeters long. I read that someone at first thought it was a snake when they saw one on their terrace.

Its mantle is always mottled, though it can sometimes appear almost entirely dark. I moved this one to my garden to keep it safe.

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This plant gets its name from its unusual ability to grow both on land and in water. In aquatic habitats, it can form extensive stands covering thousands of square meters. It grows in lakes and ponds at depths of over two meters, and can also be found on fields, riverbanks, and ditches.

Water knotweed blooms usually only in water, which makes it so exciting plant. When in bloom, vast mats of delicate flowers ripple across the water’s surface, turning lakes and ponds into floating gardens.

I discovered one of these water-garden mats while paddleboarding in the summer, and the view was absolutely stunning. I wrote a poem about it — read it by clicking the note below.♡

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This mushroom woke me with its bright purple color when I was wading through the undergrowth. It was growing on a tree stump, and its surface looked slightly fuzzy, almost like it was covered with a delicate layer of soft hair.

The silverleaf fungus can naturally prevent sprouting from birch and aspen stumps, significantly reducing regrowth and providing a biological method to manage forests and utility corridors while avoiding other harmful interventions in nature.

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This lichen really made me smile. One very big rock was completely covered with these flower-like graffiti. It grew on an island in Päijänne National Park, close to the shoreline.

There is no official name for it — not in Finnish or in English — so we called it the Marimekko-lichen. (If you don’t know what Marimekko is, just Google it!)

The edges of this lichen are orange, with black spores in the middle. I can’t be 100% sure of the Latin name — it might be Porpidia striata or Porpidia macrocarpa. If I could name this species, it would be something floral.

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