Mushrooms In Deserts: Myth Or Reality?

Mushrooms are typically associated with woodlands and grasslands, but they can also be found in deserts. Desert truffles, for example, are a type of fungus that grows in arid regions worldwide, including in Arizona, Asia, Africa, and Australia. In addition to truffles, other species of fungi, such as the Desert Shaggy Mane, have been known to thrive in these harsh environments. The Desert Shaggy Mane, or Podaxis pistillaris, is a fungus that grows in loose desert soils, especially at the bases of trees. It is commonly found in the Sonoran Desert and is known for its fibrous texture and closed cap, which protect its gills and spores from the dry conditions. While some desert mushrooms are considered inedible, others, like the Astraeus hygrometricus, are consumed as food in certain parts of the world.

Desert fungi are a variety of terricolous fungi

One of the key adaptations of desert fungi is the production of melanin, which helps them resist the intense sunlight and UV radiation prevalent in desert regions. Species such as Penicillium spp. and common soil Aspergillus spp., which are common in other environments, are not well-suited for the harsh conditions of desert habitats. Instead, desert fungi produce large, dark unicellular spores that aid in their survival. These spores enable some fungi to survive even in a state of complete desiccation, demonstrating their remarkable ability to endure arid conditions.

The physical characteristics of desert fungi also contribute to their resilience. For example, sexually reproducing ascomycetes, particularly Chaetomium spp., have evolved by developing thick, dark perithecia that provide protection from the elements. Similarly, the tough outer cortex of Astraeus hygrometricus, commonly known as the hygroscopic earthstar, allows it to persist for several years in the desert environment.

Desert fungi play a significant role in various ecological groups. They can be classified into four main categories: terricolous, epilithic, and endolithic lichens; fungi associated with plants, including truffles that grow in the Australian outback and the African Kalahari; free-living hyphomycetes and yeasts found in the soil; and microcolonial fungi that inhabit rocks and other surfaces. The presence of these fungi in desert ecosystems contributes to biodiversity and provides valuable resources for humans, such as food and medicine.

While desert fungi have adapted to survive in extreme conditions, they also pose potential risks to human health. The presence of pathogenic fungi in deserts, combined with the frequent visitation of tourists and locals, raises concerns about the impact on human well-being. Additionally, the long-distance transport of fungi and bacteria through desert dust movement highlights the importance of understanding the fungal communities within these environments to ensure the safety of individuals who may come into contact with them. Overall, desert fungi represent a fascinating and diverse group of organisms that have evolved unique adaptations to thrive in some of the Earth's most challenging habitats.

Desert truffles, a genus of truffle-like fungi

Desert truffles, also known as criadillas or turmas de tierra, are a type of hypogeous fungus that grows in symbiosis with the roots of shrubs, usually of the genus Helianthemum. They are found in desert or very arid areas, and have been found on the European continent, in the Mediterranean basin, and in various desert areas of Asia and Africa. They can occur in both hot and cold deserts and can grow in coastal sands. They are similar in appearance to traditional truffles, weighing between 30 and 300 grams and about 5 cm in diameter.

Desert truffles are a genus of truffle-like fungi within the Pezizaceae family. The species are commonly known as desert truffles and include Terfezia spinosa, Terfezia longii, Mattirolomyces, and Stouffera. However, due to recent changes in classification, no Terfezia species are known to exist in North America. The term "truffle" has been applied to several other genera of similar underground fungi, and the genera Terfezia and Tirmania of the family Terfeziaceae are known as the "desert truffles" of Africa and the Middle East.

Desert truffles are abundant and their taste and aroma are similar to those of any edible mushroom. They are traditionally consumed for their good taste, but they are also interesting from a nutritional point of view as they contain a significant amount of protein, essential amino acids, antioxidants, minerals, fibre, and omega 3 and 6 acids. This makes them a very interesting product, especially as a replacement for meat-based proteins.

Desert truffles are usually symbionts with plants of the genus Helianthemum, but they can also be found in symbiosis with other plants. Their cultivation is known as "thermiculture". The plantations become productive from the second spring after planting, with the peak productivity found in the sixth or seventh year. The compaction of the soil in which they grow affects their shape. Those grown in loose sandy soils have smoother, rounder shapes, while those in more compacted soils are quite irregular in shape with many lobes.

Desert Shaggy Mane mushrooms, a common species in the Sonoran Desert

Mushrooms are not a common sight in the Sonoran Desert. However, one species that does appear to thrive in this arid environment is the Desert Shaggy Mane mushroom, or Podaxis pistillaris. This fungus is found in deserts worldwide and is possibly the most common mushroom in the Sonoran Desert.

Desert Shaggy Mane mushrooms have a fibrous texture and a closed cap, which is thought to protect their gills and spores from drying out. The above-ground portion, or fruiting body, appears after a soaking rain. The mushrooms start out whitish, turn brown, and eventually become black powder.

In the Hawaiian Islands, Desert Shaggy Mane mushrooms are frequently found along roadsides and in disturbed areas on the dry sides of the islands, especially in Kona and Kihei. In Australia, they were used by desert tribes for body painting and to darken the white hair in old men's beards. The fungus was also presumably used by many desert Aborigines due to its distribution around drier areas of the country.

Desert Shaggy Mane mushrooms are also used extensively in traditional medicines and cosmeceuticals worldwide. While they are regularly consumed in Asia, particularly in Nepal and South Bengal, North American sources describe them as being of unknown edibility or too tough to be edible.

Fungi can survive without water for years

Fungi, including mushrooms, can indeed survive in desert conditions. Desert fungi are a variety of terricolous fungi that inhabit the biological soil crust of arid regions. They are exposed to the sun and typically contain melanin, which makes them resistant to high temperatures, dryness, and low nutrition. Some species of desert fungi include Podaxis pistillaris, commonly known as the Desert Shaggy Mane, and Astraeus hygrometricus, or the hygroscopic earthstar. These mushrooms are commonly found in the Upland Sonoran Desert and chaparral habitats.

Fungi are eukaryotic, heterotrophic organisms that include both single-celled yeasts and multicellular filamentous forms. They scavenge nutrients from the substrate they colonize or from the air or water in which they live. Many fungal species can survive in oligotrophic environments, which are areas relatively low in plant nutrients and containing abundant oxygen in the deeper parts.

While fungi need water to grow and reproduce, some species can survive without water for extended periods. For example, the tough outer cortex of Astraeus hygrometricus allows it to persist for several years in arid conditions. Additionally, some fungal species produce large, dark unicellular spores that aid in their survival in dry environments.

Climate change and weather patterns can cause fungi to adapt and expand their geographic ranges. For instance, increases in temperature and precipitation may allow some fungi, such as Coccidioides, to survive in previously unsuitable regions. However, it is important to note that most fungi cannot survive at human body temperatures and require cooler environments. As temperatures rise due to climate change, fungi may evolve to live in warmer conditions, potentially including the human body, leading to new fungal diseases.

Creative solutions for growing mushrooms in the desert

Mushrooms can be grown in the desert, though it is a challenging environment due to the lack of water and organic matter. Here are some creative solutions for growing mushrooms in arid regions:

Choose the Right Species

Select mushroom species that are adapted to arid conditions. Some species commonly found in deserts include Podaxis pistillaris (Desert Shaggy Mane), Astraeus hygrometricus (hygroscopic earthstar), and various truffle-like fungi within the Terfezia genus. These species have adaptations that allow them to survive in dry conditions, such as producing large, dark unicellular spores and developing thick, dark perithecia.

Greenhouse Cultivation

Consider growing mushrooms in a greenhouse, which provides a controlled environment. You can regulate temperature, humidity, and shade, creating optimal conditions for mushroom growth. This method allows you to mimic the 5 Fungal Needs: air, right temperatures, water/humidity, shelter, and the right substrate/container.

Raised Beds or Crates

Create raised beds or crates using wooden boards, frames, and plywood. Populate the beds or crates with a mixture of wet cardboard, craft paper, mushroom spawn, and compost. This method provides a suitable growing medium for mushrooms and helps retain moisture, which is crucial in arid conditions.

Temperature Regulation

Maintain appropriate temperatures for the specific mushroom species you are cultivating. While tropical species fruit at 80°F or higher, many other species prefer colder temperatures of around 50-70°F. In desert regions, this may involve providing shade and finding ways to keep the growing environment cool, such as burying the cultivation containers underground.

Water and Humidity Management

Ensure a consistent water source for your mushroom cultivation. While mushrooms need lots of water, you can also employ techniques to retain moisture in your growing medium. Use wet cardboard and craft paper, and consider using crates or containers that help trap moisture. Aim for 80-90% humidity during the fruiting stage.

Indoor Cultivation

If outdoor desert conditions prove too challenging, consider growing mushrooms indoors year-round. This allows for greater control over the growing environment, including temperature, humidity, and light. You can use various techniques, such as bags or buckets, to create a suitable indoor mushroom cultivation setup.

By combining these strategies, you may successfully cultivate mushrooms in desert regions, providing a source of food and potentially even medicine, as some desert mushrooms are known to have medicinal properties.

Frequently asked questions