Observation 295538: Suillus Gray

When: 2017-10-23

Collection location: St. Anthony’s Medical Center, St. Louis, Missouri, USA [Click for map]

Who: weed lady (Sylvia )

No specimen available

A fruiting of about 50+ specimens (some fresh and some aging) in soil all near soft-needled, landscaping pine trees. This is year # 3 for the occurrence of a Suillus species at this exact location. These most likely starting fruiting about a week ago – may continue. Caps quite slimy. Cap shown about 9 cm. stalk, about 3 cm. Frankly, I do not see granular dots. Maybe someone else has better eyes than I do. The cap and flesh as seen in my photos did react reddish to ammonia. Kuo does mention that for Suillus americanus.


Appears to have yellowing at the apex of stipe.
ammonia on flesh
ammonia on cap

Proposed Names

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Recognized by sight

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Add Comment
By: I. G. Safonov (IGSafonov)
2017-10-26 02:21:09 CST (+0800)

S. americanus is one of the easiest suillus species to ID, especially when young and fresh, owing to its distinct morphology. For example, see Dave W’s obs 255709. The partial veil usually doesn’t leave a ring on the stipe, but its fragments do persist on cap margins. Also, as far as I know, americanus is associated only with 5-needle pines, especially the eastern white pine. So, if your “ornamental pines” are something else, then I have my doubts about the ID.
I saw your other obsie and I think that one is americanus. FYI, it’s not uncommon for two or more species of suillus to be associated with a single host tree. Some white pines in my residential community have both “granulatus” and americanus, which sometimes fruit concurrently. One tree in particular hosts luteus and “granulatus” (obs 150958). As far as I know the former species is an exclusively hard pine associate, making that collection rather unusual, but I guess exceptions can and will happen.

By: weed lady (Sylvia )
2017-10-25 22:49:02 CST (+0800)

Was hoping I would hear from you on this observation. My first observation in November 2015 (same exact location) was # 222581. I felt good about that one. Seemed to fit the ID of S. americanus. Okay, perhaps there are two species of Suillus in the same location?? Don’t know. I would like to pin this down this time. Of course, that may not be possible. If there are no glandular dots on this current observation, then do have you an opinion of other possibilities? I will revisit the location in the next day or so. Expect there may be new fruitings, as we did have another rain recently. Will do a thorough check to see if I find anything which does have glandular dots. By the way, do glandular dots develop as the mushroom matures? Thanks for your interest and knowledge. Sylvia

By: I. G. Safonov (IGSafonov)
2017-10-25 21:12:30 CST (+0800)

Doesn’t really look like a typical americanus. The cap should be bright yellow with splashes of red or red-brown , the cap margins should be appendiculate and the stipe should sport prominent reddish-brown glandular dots.