Leaf infected with an octopus-like fungus?

During our evening walk, we came across a (maple) leaf with white/black patches, presumably a fungal infection.

Image 1

I got a thin sample from the epidermis using tape and looked at it under the foldscope. Here are some fields of view of what presumably looks like the infectious agent. It looks like something with a dense nucleus in the center and 4-6 appendages emanating from it.

Image 2

I also looked at the whole leaf under the microscope. It seems wherever there are black/white patches, the pathogenic agents seem to be condensed.

Image 3

On the suggestion of Manu and Laks, I also imaged parts of the leaf that were not infected to make sure these structures are not condensed trichomes. I did not see them in uninfected parts of the leaf.

Image 4

To be doubly sure, I went back to the same plant and took another leaf that did not have any white/black patches of infection as better control.

Image 5

Again, I did not see the structures that I saw in the infected parts of the previous leaf.

Image 6

I also imaged the impression of the uninfected part of the leaf under the microscope as I did for the infected one in Image 2. I did not see any signs of the appendages-like structure, only debris etc.

Image 7

So, it doesn’t look like condensed trichomes as per the images, and I will try to follow up on Laks’ suggestions to dig into the giant book of fungus to identify this tiny creature that is infecting the benign maple leaf.

5 Comments Add yours

  1. Manu Prakash says:

    The multi-pronged structures look like “trichomes” to me – hair cells that produce most of the chemical defense system for the plants. @laks can comment as well – but maybe when the leaf region that is affected badly does, Trichomes are released and dry up.

    Try imaging the healthy part of the leaf and see if you can identify them as well.

    Beautiful finding. Keep exploring!

    Cheers
    Manu

  2. laksiyer says:

    Hmm. Looks like a member of what is colloquially called an Ingoldian fungus. These have unusual spore structures. They are often seen in decaying fall leaves near water bodies. I have seen these spores in pond water all the time but would love a good photo-exploration of the macroscopic morphology of the fungus.

    Also as @Manu says itis good to check if it is a trichome, there are some trichomes of plants like olives that can have such radiating structures, but this one looks like a maple leaf.

  3. laksiyer says:

    C.V. Subramanian was one of the foremost mycologists in the world who described many such species in India. He had written a book on hyphomycetes which you should peruse if you have access to a good library. You might identify this genus with his book. Also some general similarity to this hyphomycete posted on microcosmos
    https://microcosmos.foldscope.com/?p=37415

  4. KanikaKhanna says:

    Hi Manu and Laks,

    Thank you for your suggestions. Indeed, in my excitement, I forgot to post pictures of the uninfected parts of the leaves and did not think about trichomes. I have updated the post now and it doesn’t look like trichomes. At least, I couldn’t find them in many fields of view that I imaged. I also went back to the same tree and imaged a leaf that did not have the black/white patches of infection to serve as better control. Nothing there either. This leaf/tree wasn’t near any water.

    Thank you for the book suggestion, Laks. I will dig into it (I did get access) and try identifying this one!

  5. Rahul Ramteke says:

    Nice,
    How you measure that….
    Pls tell…..

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