Collector’s_Name: Alden C. Dirks
Habitat: Ridge top, mixed forest, Quercus alba, Quercus rubra, Populus grandidentata, and Pinus strobus present, Quercus rubra was closest
Substrate: Ground
Host: Probably Quercus rubra
Taste_and_Odor: Taste mild, pleasant, sweet even; odor pleasant, mushroomy
Chemical_Reactions: 5% KOH darkening cap with a faint reddish hue, pitch black on pores, blue grey on flesh; iron salts darkening cap with a grey hue, greyish on pores, dark blue-grey on flesh; NH4OH did not noticeably affect cap color, bright red orange on pores, orangish red brown on stipe where it dissolved the flesh turning brown then grey over time
Spore_Print: Not Determined
Macroscopic_Features: Bolete about 10 cm tall with rhizomorphs extending into the substrate, flesh yellowish brown, staining slightly brown and blue then dark brown, base orange brown
Pileus 4.7 cm wide, 1.5 cm tall, pores .5 cm deep, surface smooth, brown with darker brown to black fibril-like look in the center
Pores .5 cm deep, bright yellow, firm, merulioid, radially arranged, bruising dark brown
Partial veil mebranaceous, thin, attached 3 mm below pores, greyish to blue grey, somewhat translucent, tearing
Stipe clavate, 8 cm long, 2.5 cm wide at the base, 1.5 cm wide at apex
Microscopic_Features: Narrowly cylindrical, subfusiform to oblong spores, length (8.3) 10.0-13.3 (15), width (3.0) 3.8-4.7 (5.5), Q (2.2) 2.5-3.1 (3.6), 65 spores measured
Basidia with 4 sterigmata, cystidia present, pileipellis a cutis
Other: I cannot identify this specimen. At first I was thinking Paragyrodon, but lots of characteristics were off and the spores are not subglobose. But it does not key out with any Suillus species. It was growing close to an oak, Quercus rubra, as well as an aspen, Populus grandidentata. There were white pines in the area as well.

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Alternative tree hosts for some Suillus
By: I. G. Safonov (IGSafonov)
2021-01-11 11:47:44 EST (-0500)

Last year at Stokes S.F., I observed S. americanus, S. spraguei, and S. weaverae all growing next to each other in a hemlock grove. I spent a long time looking for a white pine nearby (examining bark and canopies), but couldn’t see any. I was excited about this interesting discovery. In other parts of the grove, however, I saw what looked like white pine seedlings.

Suillus spraguei can lose it’s red color.
By: Dave W (Dave W)
2021-01-11 10:04:40 EST (-0500)

Here’s another example obs 210863. The one seen in Alden’s post (339920) is quite an aberration; IMO the strangest thing being the apparent lack of ornamentation on the cap surface. My guess is this is the result of a sequence of specific/unusual weather events.

S. spraguei is very common in my area. I know a few spots where it is found quite far from the nearest white pine (stepped off up to 2x the height of the nearest mature pine). So I considered the possibility that perhaps where it is a well-established symbiont of Pinus strobus, it may spread to other tree species (such as hemlock, which is often the dominant tree species in these locations). At a NEMF foray I got into a conversation with Gary Lincoff and Rick Van de Poll. Both were quite adamant about this not being the case. So, I surmise there’s good research to support the single associate hypothesis for S. spraguei.

By: I. G. Safonov (IGSafonov)
2018-10-19 12:54:18 EDT (-0400)

Yes, it’s an exemplary post, very well-documented, as it should be for a suspected unknown species, with the habitat description, chem tests, spore measurements, and nice pix to complement the standard battery of data. Better to have all that than not and then keep guessing! Thanks for posting!

I made sure to document everything thoroughly,
By: Alden Dirks (aldendirks)
2018-10-19 11:31:59 EDT (-0400)

thinking, “this is it!” haha. It didn’t match anything. But it makes sense, and I suspected something was up because the cap was dry and a little shriveled. Yet, the rest of the fungus looked to be young and in great condition. Maybe the reddish tints on the stem were a hint.

Thanks for your help!

By: I. G. Safonov (IGSafonov)
2018-10-19 10:36:29 EDT (-0400)

I was looking and it and thinking what else could it be? So I checked the weather in Madison, WI, and there were a few nights with below freezing temps before the 18th. This was collected outside of town, so it must have been even colder there. So the freeze-thaw cycles have likely changed its appearance enough to have us scratch our heads. Also, you said white pines were nearby, no other conifers, and P. strobus is the only host for spraguei.

Hi IGSafonov,
By: Alden Dirks (aldendirks)
2018-10-19 02:07:10 EDT (-0400)

This specimen looks so different from typical Suillus spraguei specimens. Do you think it is just old?