Mycelium is the vegetative part of a fungus, forming a vast network of branching, thread-like structures called hyphae. This intricate system functions as the “root system” for fungi, actively absorbing nutrients from its environment. It extends through various substrates, playing an important role in decomposition and nutrient cycling.
Visual Characteristics
Mycelium most commonly appears white, though its color can vary depending on the fungal species and the substrate it grows on. It can range from off-white, cream, or light grey to shades of yellow, orange, or even blue and green. For instance, certain morel mycelium can exhibit yellow and orange hues, while some mushroom species may show blueish tones, particularly if bruised.
The texture of mycelium is also quite diverse, often appearing fuzzy and cottony (tomentose growth). Alternatively, it can present as thin, stringy, and organized root-like structures (rhizomorphic growth). This network can form dense mats that spread across surfaces, indicating vigorous growth.
Growth Patterns and Habitats
Mycelium exhibits two primary growth patterns: rhizomorphic and tomentose. Rhizomorphic mycelium develops as dense, organized, root-like or rope-like strands that spread rapidly, efficiently colonizing substrates. This pattern is often associated with robust and aggressive growth, signaling readiness to produce mushrooms under optimal conditions.
In contrast, tomentose mycelium has a fluffy, cotton-like texture and tends to spread in a more diffuse, less organized manner. While it may colonize substrates slower than rhizomorphic growth, it is a common form for many fungal species. Mycelium can be found in diverse habitats, including underground in soil, decaying wood, logs, compost, or grain-based substrates. It also forms symbiotic relationships with plants, extending their root systems to enhance nutrient absorption.
Telling Mycelium Apart From Other Growths
Mold, also a type of fungus, typically presents as a superficial growth that can be green, black, blue, or other colors, often appearing powdery or slimy. Unlike the organized network of healthy mycelium, mold growth is often less structured and can appear in isolated patches, sometimes with a distinct musty or unpleasant odor. Healthy mycelium is primarily white and generally has an earthy or neutral smell.
Mycelium has a softer, often fuzzy or cottony texture, or it can be thin and thread-like. Plant roots, conversely, are generally firmer, more cylindrical, and typically lack the extensive, web-like branching pattern characteristic of mycelium. While both absorb nutrients, visual and textural distinctions help differentiate these underground structures.