Observation 137485: Amanita amerirubescens Tulloss nom. prov.

Did not immediately bruise red, but nearby collections may have had red bruises.

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And, to add to David’s comments, manual bruising usually does not
By: R. E. Tulloss (ret)
2013-06-24 12:17:35 PDT (-0700)

immediately result in staining. The bruising appears to be due the early portion (at least) of the melanin cycle. Tyrosinase triggers the cycle by facilitating oxidation of a phenolic compound. You can watch this happen in (shorter) real time by slicing the mushroom down the center vertically and lifting off a thin silhouette layer from the cross-section. Place this on a glass or ceramic surface and “paint” it with 1% paracresol or a saturated (boiling) solution of L-tyrosine. The former is a heck of a lot easier to handle and can be done without a stove or a campfire. You will get a very rapid red reaction in amerirubescens…and many other amanitas. The reaction does not take place throughout the fruiting body in all species or in all stages of growth in a given species. Interestingly, A. brunnescens must have an entirely different method of producing its reaction to bruising as the above mentioned reagents don’t produce a significant response in brunnescens. The above reagents are known to be specific for detection of tyrosinase among the larger class of phenolic compound oxidizing enzymes.

Very best,


Emma, sometimes the staining…
By: Dave W (Dave W)
2013-06-24 11:01:04 PDT (-0700)

is more immediately evident on the context, especially inside the stipe base.

For some reason your photos are not enlarging when I click them.

Created: 2013-06-24 10:35:01 PDT (-0700)
Last modified: 2013-06-24 10:35:02 PDT (-0700)
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