Mushrooms, the visible fruiting bodies of fungi, often appear to vanish with cold weather, leading to a common misconception that they cannot endure winter. However, many fungal species, including those that produce mushrooms, possess remarkable adaptations that allow them to survive and even thrive in cold temperatures. While some disappear, others employ sophisticated biological mechanisms to persist, challenging the idea that they are solely creatures of warmth.
How Mushrooms Tolerate Cold
Fungi have evolved several biological and physiological mechanisms to withstand freezing temperatures. Some species produce specialized antifreeze proteins (AFPs), which are polypeptides that bind to small ice crystals within cells, preventing them from growing larger and causing cellular damage. These proteins inhibit ice recrystallization, a process that would otherwise be fatal to the cell.
Another strategy involves dehydration or entering a dormant state. By reducing their cellular water content, some fungi minimize the risk of ice crystal formation. This dormancy also slows down metabolic processes, conserving energy and protecting cellular structures from cold-induced damage.
Fungi can also accumulate compatible solutes, such as trehalose and glycerol. These compounds act as cryoprotectants, lowering the freezing point of the cell’s internal environment and helping to protect cellular components from cold stress. The composition of fungal cell walls, primarily made of chitin, glucans, and proteins, also contributes to their resilience by providing structural integrity and protection against environmental stresses.
Mycelium, Spores, and Fruiting Bodies in Winter
The various parts of a fungal organism cope differently with cold conditions. The mycelium, an extensive, thread-like network typically hidden beneath the soil or within a substrate like wood, is often the most resilient part. This underground or internal location provides insulation, protecting the mycelial network from extreme temperature fluctuations. The mycelium can remain dormant or maintain slow metabolic activity throughout winter, ready to resume growth when conditions improve.
Fungal spores, designed for dispersal and long-term survival, are highly resistant structures. They can endure harsh environmental conditions, including prolonged periods of cold, remaining viable until favorable conditions return. In contrast, the visible fruiting body, or mushroom, is generally the most vulnerable to freezing temperatures due to its high water content. While many fruiting bodies decay or die back in severe cold, some species are adapted to emerge even in cold conditions or are short-lived, completing their reproductive cycle before harsh freezes.
Mushrooms That Endure Cold Climates
Despite the general vulnerability of fruiting bodies to cold, several mushroom species are well-known for their ability to thrive in chilly conditions. The Enoki mushroom (Flammulina velutipes), for instance, is a common cold-weather species that fruits in late autumn, early spring, and even throughout winter in moderate climates, sometimes appearing through snow. These mushrooms often grow on dead hardwood trees.
Certain strains of Oyster mushrooms (Pleurotus ostreatus) also demonstrate significant cold tolerance. Some varieties, known as Winter Oyster Mushrooms, are particularly resilient and fruit from November through April, even after frosts. Turkey Tail mushrooms (Trametes versicolor) are frequently found year-round, including in winter, growing on dead hardwood stumps and logs. Winter Chanterelles (Craterellus tubaeformis) are known to withstand cold and can often be found in coniferous and deciduous woodlands well into December, even surviving initial frosts. These examples highlight that while many mushrooms are seasonal, a surprising number have evolved specific adaptations to persist and produce fruiting bodies through colder months.