Danny’s DNA Discoveries – Russula
by Danny Miller
Clade Russula “crown” - Shrimp Russulas
These large, mild tasting Russulas smell like shrimp, at least in age. In the “crown” clade, only these, R. ‘olivacea’, R. vinosa and R. benwooii regularly get >15cm across. A drop of FeSO4 turns them green, which doesn’t usually happen in any other group. The flesh is especially susceptible to browning, the stems are sometimes flushed pink and they can be almost any colour of the rainbow, unfortunately. Like most of the crown species, the spores are rather dark yellow so the gills are quite yellow in age. They are some of the most popular edibles in Russula, probably because they are easier to identify than most, not because they are the best tasting. They are not as dense and well-textured as some other species, but the shrimpy-ness disappears in cooking.
In this section I will also discuss the sometimes similar R. 'olivacea', which does not smell like shrimp, nor usually brown as much but is a denser large mushroom also with a stem flush.
Russula sp. Woo 61 (aff xerampelina)
Our species is significantly different genetically than the European species, so it needs a new name, although I do not yet know of a way to separate them other than by country of origin and genetics. It is usually wine coloured (some shade of purple, red or both). There is often a lot of pink stem flushing. It is usually found with the typical Doug fir and hemlock and other conifers. Since this is one of the easier groups of Russulas to identify, it is a popular edible.
R. sp. Woo 61 (aff xerampelina) © Ben Woo
Russula viridofusca (Woo 59)
This shrimp Russula is also found with different conifers but is usually pale, pinkish-, yellowish- or olive-tan and has little stem flushing. It can be greenish or even reddish and so probably can’t be unmistakenly differentiated from the others. Some locally have called it R. ‘isabelliniceps’ but that was never an official name and R. viridofusca, described from Washington in 1979, is an official name. It is very common, collected by Ben more often than R. ‘xerampelina’ (31 vs 13 times), but that may be because he didn’t feel the need to sample the latter very often.
R. viridofusca © Ben Woo
R. favrei (Woo 60)
We have been calling this Russula elaeodes, but that species is probably the same as R. pseudoolivascens and R. clavipes, which turns out to be something different. Our species matches a pretty unanimous consensus of what the European R. favrei is, found with conifers. Here it might prefer hemlock and spruce. Its colour scheme is usually brown with an especially dark brown center. It has little stem flushing just like R. viridofusca. Perhaps it can have purple tones like R. ‘xerampelina’ so it also may not be easy to distinguish.
R. favrei © Ben Woo
Russula sp. Woo 58 (cf olivacea)
This is not a shrimp Russula, but it shares some features. It’s large and has a pink flushed stem with fairly dark yellow spores. But this is an especially dense Russula (so some say it is one of the best edibles but others caution about possible poisonings), with a somewhat velvety purple and/or green cap that has a very interesting texture when fresh. It does not smell of shrimp. It does not usually brown as much as the shrimp Russula and FeSO4 will not usually turn it green, but both of those are variable features as I have found one collection that browned significantly and did turn green in FeSO4. It turns out we do not have the real R. olivacea here, but a sister species. It will need a new name. It is usually found with conifers like Doug fir, hemlock and spruce.
R. sp. Woo 58 (cf olivacea) © Ben Woo