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Characteristics of Fungi: Hyphae

As I mentioned, when fungi grow vegetatively, they produce what are called hyphae, and this is a photo of the hyphae of a fungus called Rhizoctonia, which is a very common root rot organism. You can see how long and tube-like these structures are. They’re kind of like threads. Also, if you take a look at where the black arrow is pointing, you’re going to see tiny little lines and those are what are called cross-walls. That’s what divides that long tube into individual cells, and you can find these in certain types of fungi. Oftentimes in the fungi-like organisms, these particular structures are missing, and so, that’s one of the things that I tend to look for when I’m examining fungi under the microscope. I’ll definitely look for cross-walls, because if I don’t see them, I get a little bit excited, because that can indicate I’m dealing with a water mold, and the water molds oftentimes are some of the more destructive of the root rot organisms that I deal with.

Rhizoctonia itself is also a destructive root rot organism. That’s what’s shown here. What is distinctive about this particular organism is that it doesn’t produce spores, and really, the only way you can identify it is based on its hyphae. What I do to identify this particular organism is I look at places where the hyphae branch. And, again where the black arrow is pointing here, you can see a branch point. And, then I look to see where that cross-wall at the branch point is produced. If it’s flush with the original hypha from which the branch has been produced, then it’s not Rhizoctonia. But, if that cross-wall is offset just a little bit forming kind of a T-shaped cell at that intersection, then I know I’m dealing with this organism called Rhizoctonia, and I know I have a problem with a potential root rot organism.