Oyster mushrooms on poisonous trees

Nature Talk
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Hi. I found what I think are pink oyster mushrooms on a tree I know is poisonous. Can this make them unsafe to eat in case I wanted to do so?

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It might help to mention what the tree species is. Different plants have toxic compounds in different parts of their body, and different compounds will be uptaken differently by consumers (the fungi in this case) on a biological level.

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It is Cascabela gaumeri, a native tree in the oleander family (Apocynaceae), and a close relative of the much more famous Cascabela thevetia. The toxins are cardiac glycosides, as in milkweed and oleander.

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I’d play it safe - leave the fungi to complete their life cycles and sustain their invertebrate biodiversity.

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The mushrooms are growing on the ‘‘deadest’’ part of the tree, so I hope the toxins would have degraded or something.

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Does anyone else have an answer to this?

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Not a fungi expert, but I’ve read a number of papers about the ability of fungi to absorb toxins from their environment and normally edible species can definitely become toxic. I wouldn’t risk it.

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Do you have a link to the papers you’ve read? I’d be interested in looking them over.

IMHO I’d play it safe but this doesn’t mean the mushroom is, in fact, toxic - but it is firmly in the ‘this specific occurance probably hasn’t been studied so it’s hard to give a for-sure answer’

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I can only seem to find one of the papers I was referring to, here Analysis of Several Heavy Metals in Wild Edible Mushrooms from Regions of China | Bulletin of Environmental Contamination and Toxicology (springer.com) . The others (I think there were two more that I read) came to very similar conclusions.

In the process of digging that one up, I did come across some newer ones on the subject Research Progress on Elements of Wild Edible Mushrooms (mdpi.com)
Uptake of toxic and nutrient elements by foraged edible and medicinal mushrooms (sporocarps) throughout Connecticut River Valley, New England, USA | Environmental Science and Pollution Research (springer.com)
Both of these seem to suggest that mushrooms will uptake toxic elements but that most of the time this occurs at sublethal doses.
I don’t know about plant toxins specifically - I imagine it’s possible, but I don’t think it’s common. I agree, in this case it’s probably not toxic, but if it is, it’s not worth finding out the hard way.

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