(pl. Hyphal Systems)
Terms discussed: binding hypha (pl. binding hyphae), dimitic, generative hypha (pl. generative hyphae), monomitic, pseudodimitic, skeletal hypha (pl. skeletal hyphae), trimitic
See Also:
clamp connection
Polypores often have more than one type of hyphae in their fruiting bodies. The hyphae that are usually still alive and bear the spores are called the generative hyphae. A polypore that has only generative hyphae is said to have a monomitic hyphal system. The other two kinds of hyphae are skeletal hyphae (long, unbranched, thick-walled hyphae) and binding hyphae (sometimes thick-walled, tremendously and frequently branched). Skeletal and binding hyphae are usually empty of cell contents, which travel continuously to the very tip of the growing hypha, leaving empty cell wall structures behind. It is these empty hyphae that make many polypores so tough and hard.
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A polypore that possesses all three types of hyphae is said to be trimitic. If it possesses generative hyphae and one other type, it is dimitic. Almost all dimitic polypores have generative and skeletal hyphae; the exceptions are those in the genus Laetiporus, which have generative and binding. The hyphal system in the picture above is dimitic: two strands each of clamped generative hyphae and unclamped skeletal hyphae.
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Generative hyphae is the only type that is allowed to have clamp connections. It is not required to have clamp connections: some polypores have simple-septate generative hyphae. But any hyphae with clamps are automatically considered generative. I believe that this is a conceptual error - - some polypores have clamped hyphae that are thickened, rarely branched, and obviously serving the purpose of skeletal hyphae. But that's the system we have. There is a special term for polypores with clamped skeletal-like hyphae, however, and that is pseudodimitic. So although you can't describe the thickened hyphae productively with this terminology, you can at least describe the hyphal system accurately.
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