Molds are filamentous fungi that are classifi ed based on the morphology of asexual or vegetative mycelial elements and their spore structures. A typical vegetative structure of molds consists of individual hyphal elements, collectively called the mycelium. Hyphae are of three types: (a) penetrative hyphae called rhizoids, which serve to enter the substrate to glean and transport nutrients; (b) stolons, which have a larger diameter than rhizoids and serve to link the mycelial mass, and (c) aerial asexual reproductive hyphae, also known as conidiophores or sporangiophores. Depending on the mold, asexual spores may be produced within an enclosed structure (the sporangium) or appear exposed at the tips of vesicles. Spores serve an important role in mold dispersal, being carried by air currents and foraging insects. Under appropriate conditions of humidity and temperature, spores germinate to yield the vegetative body (mycelium), which can continue to alternatively propagate and sporulate.
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