Basic mycology terminology: What does the term “mycelium” specifically describe in filamentous fungi?

Introduction / Context:
Two foundational terms in mycology are “hypha” and “mycelium.” Accurately distinguishing these terms is crucial for describing fungal structure, growth, and colony morphology in laboratory and field contexts.

Given Data / Assumptions:

• Hypha: a single, tubular filament (septate or coenocytic).
• Mycelium: the macroscopic/microscopic network formed by many hyphae.
• Ascus: a specialized sac of Ascomycetes where ascospores are produced.

Concept / Approach:
The body of a filamentous fungus is typically a mycelium. While a lone hypha can extend and branch, the term “mycelium” refers to the collective mass. Accurate terminology aids in correct identification and communication of morphological features.

Step-by-Step Solution:
Define hypha and contrast with mycelium. Exclude ascus (a reproductive sac unrelated to the structural definition of mycelium). Identify mycelium as many intertwined hyphae. Select the option describing an interwoven mass of hyphae.

Verification / Alternative check:
Colony descriptions often state “white, cottony mycelium” reflecting the aggregate of aerial hyphae seen on agar plates.

Why Other Options Are Wrong:
An ascus is reproductive and specific to Ascomycetes; a single filament is a hypha, not a mycelium; budding yeast are unicellular and do not produce mycelium in the strict sense.

Common Pitfalls:
Using “hyphae” and “mycelium” interchangeably; they denote different hierarchical levels of organization.

Final Answer:
An interwoven mass of numerous hyphae forming the body of the fungus.