Mushroom Growth: Overnight Emergence Explained

Mushrooms are a mysterious form of life, and one of the most fascinating things about them is how they can seemingly pop up overnight. This phenomenon has sparked curiosity among naturalists and readers alike, who wonder how and why mushrooms grow so fast. The answer lies in understanding that mushrooms are not plants but fungi, and their growth is more akin to inflating a rubber glove than a plant sprouting from a seed. Fungi expert Merlin Sheldrake compares mushrooms to fruit, stating that they “rapidly inflate with water, which they must absorb from their surroundings. This is why mushrooms often appear after rain, as their growth can be triggered by warm, damp weather.

Mushrooms are the reproductive bits of a larger mycelial network

Mushrooms are a fungus, and like all living species, their goal is to survive and reproduce. They are the reproductive bits of a larger mycelial network. Mycelium is the primary form of the overall fungus. It grows throughout a substrate, such as soil, living and fallen trees, insects, and other sources of nutrition. The mycelial network infiltrates its food source, releasing digestive enzymes, breaking it down, and then absorbing the nutrients. Once the fungi have fully digested a substrate, what remains is highly rich in organic material, benefiting the ecosystem by spiking the soil with bioavailable nutrition that it unlocks through its unique digestive process.

Mycelia are vital in ecosystems for their role in decomposing plant material. They contribute to the organic fraction of soil, and their growth releases carbon dioxide back into the atmosphere. Mycelial mats have been suggested as having potential as biological filters, removing chemicals and microorganisms from soil and water. The use of fungal mycelium to accomplish this has been termed mycofiltration. Mycelium is also an important food source for many soil invertebrates.

Mycelial networks can be both large and small. Most are microscopic, but some fungal species can also grow to colossal sizes. In the United States, an Armillaria ostoyae growing under the Malhuer National Forest in Oregon is estimated to cover almost 10 square kilometres, making it one of the largest single organisms in the world. The biggest known organism on the planet is a honey mushroom in Oregon, covering 2,200 acres and thought to be about 2,400 years old.

Mushrooms are the temporary reproductive portion of a much larger fungus. Below the mushroom's surface (called a fruiting body) is a vast network of thin, root-like threads called the mycelium. The mycelium also plays a crucial role in fungal reproduction. The mycelia of two compatible fungi can fuse together, allowing the cells of each fungus to combine and their DNA to mix. After fusing, the cells end up in new spores held inside (like in truffles) or exposed outside (like in mushrooms and crusts) the fungus' reproductive structures. This is essentially how some fungi reproduce when the environmental conditions are right.

Rain and cooler weather trigger the appearance of mushrooms

Mushrooms are a mysterious type of fungus, and their rapid appearance can be surprising. They can often appear to come up overnight, fully formed, and seemingly out of nowhere. This phenomenon is triggered by rain and cooler weather, which provide the ideal conditions for mushrooms to rapidly inflate with water and push their way up from the ground.

Fungi, including mushrooms, thrive in damp conditions. While a lawn may be regularly irrigated, it is the natural downpour of rain that can really get things moving for mushrooms. The rain provides the water that mushrooms need to inflate and grow. In addition, cooler weather provides an ideal temperature for mushrooms to flourish.

The appearance of mushrooms is not just a result of the external environment. It is also due to the presence of spores and the growth of the mycelium, the main part of the fungus, which lives underground. The mycelium can be months, years, or even decades old before it reveals its presence with mushrooms. The mycelium grows unseen in rotting logs, rich humus, and dark, damp places. Mushrooms are the reproductive structures, or fruiting bodies, of this larger fungus body.

The rapid growth of mushrooms can be quite impressive. They can push aside leaves, sticks, or even crunch through asphalt roads with an explosive force. This growth can occur at a rate of about 0.2 inches (0.5 centimeters) per minute, which is so fast that a crackling sound can be heard as the tissues swell and stretch. The next time you see mushrooms that have popped up overnight, remember the complex and fascinating process that made it possible.

Mushrooms grow by inflating with water

Mushrooms are a unique life form, distinct from plants and more closely related to humans. They are not photosynthetic and must obtain their food from pre-existing material. Their growth is often puzzling, as they seem to appear overnight, fully formed. This phenomenon is due to their ability to rapidly inflate with water, which they absorb from their surroundings.

Fungus expert Merlin Sheldrake, in his book "Entangled Life," compares mushrooms to "bunches of grapes growing out of the ground." He highlights that mushrooms rapidly inflate with water, which is why they often appear after rain. The growth of mushrooms can generate an explosive force, as demonstrated by the stinkhorn mushroom, which can produce enough force to lift an object weighing 130 kilograms.

Mushrooms consist of approximately 90% water. Fungi, the broader category to which mushrooms belong, require water for all stages of their life. They secrete enzymes that break down organic matter, and these enzymes depend on water to function effectively. When the substrate is too dry, fungi demonstrate their interconnected nature by transporting water from moist to arid areas through hydraulic redistribution.

The growth of mushrooms is influenced by the water potential of the substrate and fungal tissues. Water naturally flows from areas of high water potential to areas of low water potential when unobstructed. This movement of water is facilitated by pressure differences that arise during growth, differential osmolyte uptake, and external osmotic conditions. The presence of aquaporins may also contribute to water uptake under certain conditions.

While the cell volume of fungi does not increase significantly with water uptake due to the presence of a cell wall, the cell membrane exerts higher pressure on the cell wall, resulting in turgor development. This process allows mushrooms to rapidly inflate with water and contribute to their seemingly sudden appearance.

Mushrooms can push up through asphalt

Mushrooms can indeed push up through asphalt, as well as concrete and tarmac. This phenomenon is often puzzling, given that mushrooms are soft and squishy, yet they can exert enough force to lift pavement and even crunch through asphalt roads.

Mushrooms are the fruit of fungi, like grapes on a vine. They grow rapidly by absorbing water from their surroundings, which is why they often appear after rain. This mushroom growth can generate an explosive force. For example, the stinkhorn mushroom can generate enough force to lift an object weighing 130 kilograms as it crunches through asphalt.

To prevent mushrooms from pushing up through asphalt, it is important to ensure that there is no organic material or rotting debris underneath the asphalt that could serve as a food source for the mushrooms. Properly preparing the surface before laying asphalt can help to prevent mushrooms from growing. However, even with proper preparation, mushrooms may still find a way to push through asphalt, as they are incredibly resilient and determined.

If mushrooms have already pushed up through existing asphalt, the only way to fix the problem may be to tear up the asphalt and remove the mushrooms' food source. Patching the asphalt may not be effective, as the mushrooms can continue to grow underneath and push through again. Waiting for the organic material to decompose completely may also be an option, but this could take a significant amount of time.

Mushrooms are not troublesome to lawns

Lawn mushrooms are a clear indication that beneficial microbes are actively working in your lawn, contributing to the overall ecosystem of your yard. Mushrooms are more than just a culinary delight; they signal the presence of nutrient-rich, fungi-filled soil, which depends on organic matter from trees and shrubs for its vitality. Fungi play an essential role in decomposing lignin-based organic materials found in various woody substances, such as tree roots, stumps, leaves, decaying mulch, and twigs.

Mushrooms often appear after periods of excessive moisture, as this extra water can boost beneficial microbial activity and provide the fungi with the ability to produce a fruiting body, which is the mushroom itself. Rain and cooler weather can trigger the sudden appearance of mushrooms, which are not generally troublesome to lawns. They also tend to appear in lawns primarily when there is decaying wood present.

While mushrooms themselves are not harmful, the conditions that invite them can also bring in less friendly lawn fungi. Therefore, it is important to address the underlying causes of mushroom growth, such as reducing excess moisture, improving drainage, and aerating the soil.

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