Observation 139432: Amanita rubescens sensu auct. amer.
When: 2013-07-10

Notes: On ground under oak, conifers near by. Cap 95 mm, pink buff with buff patches densely distributed, flesh turning pink when cut, no striation at margin. Gills cream, close, broad. Stem 97 mm x 11 mm, red pink, ridged, swollen at base, no ring, no bulb. The three specimens in this group were older and badly eaten by insects and slugs. This was the best of the group but a large adjacent FB (cap 150 mm) had a large bulb (50 mm long) and no intact stem. The gills did not bruise red and the stem was too far gone to tell.

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Used references: www.amanitaceae.org

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Thanks for pointing me to this observation, Teresa.
By: R. E. Tulloss (ret)
2013-07-10 20:17:06 PDT (-0700)

I don’t have an alternative suggestion for you.

It sounds like you damaged the gills and didn’t see any bruising staining when you did so. The rubescens group can take a little while for the staining to happen; it doesn’t happen right away. Also, if the a surface has become dry (including a broken surface on exposed flesh, then the staining of that surface can become suppressed for lack of moisture. I think that the staining is a process that requires damage to cells which still have their liquid contents. From experiments testing for phenoloxidases in mushrooms (by breaking cells and applying a phenolic compound to be oxidized) I am pretty sure that rubecens’ staining involves the initiation of a pigment making cycle by an enzyme called tyrosinase that grabs a phenolic compound and starts a process that generates one or more pigments. This is wet chemistry and is not going to happening on dry surfaces.

Very best,

Rod

Created: 2013-07-10 17:00:41 PDT (-0700)
Last modified: 2014-07-19 15:28:24 PDT (-0700)
Viewed: 23 times, last viewed: 2016-10-25 02:39:24 PDT (-0700)
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