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Hi, I hope you can shed light on what I’m pretty sure is a Russula sp. Habitat: A widely spaced group growing near the base of an oak tree in deciduous woodland.
Cap: Sample – 3cm, convex, beige to light brown, suede, dry feel, very crumbly; stem, white, 3cm; gills white, close.
Cap of other specimens up to 6cm, becoming depressed, pale orangey brown.
No bruising but flesh of stalk going beige when cut.
No particular taste or smell noticed.
Spores: No apparent spore print! But spores found on gills. Subglobose, 6.33-7.96 x 5.03-7.18um
Framed inset in images of spores is an EDF composite.
The spore size seems relatively small for a Russula, it’s not red, so maybe that narrows down the options!
Many thanks… Nick
Hello, without the spore print colour and the chemical reactions on FeSO4 and Guajak it is not possible for me to narrow it down to something.
I could imagine that it is one of the Xerampelinae, but then it should have a greenish reaction on FeSO4.
best regards,
Andreas
Nick, have you got Geoffrey Kibby’s book on Russulas. Its fairly cheap and has a useful key. Part of this is taste, and also spore colour as Andreas says which varies from pure white to ochre.
Out the cap on glass for a spore sprint. If you are using paper, you wont see the colour if it has white spores. It would need covering and perhaps leaving overnight and kept moist.
No particular taste would mean mild, as it is either mild, hot or bitter.
Many thanks, Andreas and Adam, for the feedback and suggestions. It was odd, this is maybe the first time I’ve not got a spore print from a cap. I use smooth black plastic rather than white paper, and I actually left half the cap on a slide – but nothing. I didn’t cover the cap as usual so maybe I failed to keep it moist – aargh!
I tasted the cap on site, and as nothing bit my tongue, I’d say it was mild.
I’ll go back to the site and see if I can get another specimen.
So, what I need to order is:
Ferrous sulphate (10%) in distilled water 10mL
Guaiac (Guaiacum resin in alcohol) for Russulas 10mL
The Genus Russula in Great Britain: with Synoptic Keys to Species by Geoffrey Kibby
And then I should be ready to tackle Russulas?
All the best… Nick
And a sulphovanillin kit is you are really determined. Its for looking for the dermatocystidia as this is an important part of the key. Its not the nicest stain to use (strong sulphuric acid) and apparently people have had some success with other stains but SV really shows them up beautifully.
Hello, best is to taste the gills of young specimens, the flesh is often significantly milder than the gills.
Spore print is best done on white paper, to see the little difference to off-white (Ib) and light cream (IIa). Of course you see a white spore print also on white paper though it is the same colour. Best is nevertheless to you a microscope slide or any other glass, as you have to scratch the spore print to a heap with a razor blade, and when you scratch Spore print on paper, you also scratch some of the papers surface together with the spores and this will probably result in a lighter colour than it realy is.
The usage of Guajak is very often not correctly done or misinterpreted – e.g. the notations in FoS which are all useless as the emphasis a certain shade of blue or green, which is not the important thing, but the time how long it takes for the brown drop to switch to blue/green – and as they don’t indicate the time you can not use their information about Guajak at all ….
Kibby is a nice booklet to start with and often you get a correct result, and it is a very good step stone to get deeper into the genus, but it can’t substitute a monograph like Sarnari
best regards,
Andreas
Crikey! I thought this was going to be easy! I’ll order the basics (not sure about the sulphuric acid) and hopefully get back to you with a detailed description.
Many thanks, again, for all your advice… Nick
Wildlife has eaten my mushrooms! Amongst scattered remains, I did find a small, fresh specimen and a dryish cap. Encouraged by your advice, Kibby (2017) and the speedy delivery of supplies by Microscience Ltd (many thanks John), I’ve pressed on. So: Habitat: Widely spaced group growing near base of oak tree in deciduous woodland.
Cap: 3cm – 6cm; pale brown darkening slightly to top, roughly convex, either domed or with slight central depression, maturing to pale orangey brown, broad with central depression. Slightly sticky when wet. Suede feel when dry.
Cap (Kibby): Colour light F (or possibly dark C). The skin on the dried cap peeled to half way (Kibby I).
Gills close, cream.
Stem: Length similar to width of cap, e.g., 4cm cap, stem 40mm x 1.5cm; white, no obvious bruising. Kibby colour K, size N.
Spore print: White; Kibby P
Taste: Mild; Kibby T
Smell: Not distinctive.
Spore size: Sub-globose to ellipsoidal; 6.2 – 8.5 x 5.2 – 6.8μm; warts low, up to 0.5μm
Spore image: Mountant – Meltzer’s reagent; EDF composite
FeSO4: Rapid change to pink
Guaiac: Rapid change to blue
Cuticle: I don’t know how to do this – any advice?
Kibby code: FIKN + PT(?)
Possible ID: Russula vesca.
Kibby’s line drawing of R. vesca spores shows the warts to be small and isolated. However, the spores in the images by Pellicani (Association des Mycologues Francophones de Belgique) are not dissimilar to mine.
R. vesca?
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