| Re: Carmine colouration on R. aurora caused by sulphovanillin Geoffrey Kibby has very recently produced an updated synoptic key to the genus Russula in Great Britain.
For Russula aurora he says:
"Habitat: Fairly common early in the season, usually with Fagus, Castanea or Carpinus. Notes: Often confused with other red species but easily distinguished by its SV reaction and 1/2 peeling cap. (R. lepidicolor is very similar but has adnate cuticle and pruinose cap.)"
Here "adnate cuticle" means the cap peels only at the very edge. R. lepidicolor is "very uncommon to rare in the south of England, usually associated with beech, very few authenticated records."
Both have the red reaction with sulphovanillin (SV). However, R. aurora is clearly much the commoner. So if you find a red Russula with a red reaction to SV you almost certainly have Russula aurora. If the cap cuticle peels to half way, then you can be confident of your identification. If it doesn't peel you would need to do some more detective work because it might just be an old specimen.
Ken |