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Danny’s DNA Discoveries – Lactarius

by Danny Miller


Deliciosi clade


Lactarius 'deliciosus' group

I have no idea how many species we have in this group. We don't have the real L. deliciosus, nor do we appear to have the real L. deterrimus as has been reported, but we have about 10 local sequences, few of which match each other, all within about 2% of each other in ITS. Perhaps this represents just one species with an unusual amount of genetic variation, or perhaps it will be decided to split this into some number of species. Besides all the closely related sequences, we also have a handful of individual sequences from Eastern Oregon that are 5% different or more from each other, but it's suspicious that none of those sequences has yet occurred twice. Some sequences could have errors. L. deliciosus var areolatus is a name from the east, but it looks like that variety's DNA has not been found in the PNW, so that's not likely a name we'll ever use.

L. deliciosus var. olivaceosordidus is a good name from the west, but 2 or 3 different sequences have come out of mushrooms matching that description. One of our species will likely be called that, but it's not clear which one and if it will remain a variety or be promoted to species. It has muddy or reddish carrot coloured latex and yellow flesh under the cap.

As a group, the L. deliciosus group mushrooms usually have zoned caps that are orange with orange latex that may turn reddish when exposed to air, scrobiculate stems, and they turn significantly green in age or after handling, making them quite remarkable. The taste is usually mild, but some may be bitter (like black pepper, not a hot pepper) and some may show a bit of the hot pepper acrid taste so common in other clades, but not usually found here. You can help us figure out how many species we may have by noting the tree associations (pine or spruce may make a difference and there may be other choices as well), how much they green and the exact colour of the latex and if it changes over time and how quickly. If we can find patterns and get sequences of them, perhaps we can someday figure out how many species we have and how to tell them apart.

A few similar mushrooms, not as closely related as the mess of species I have discussed so far (and therefore lower hanging fruit), have been recently sorted out and named (they were probably picked because they were lower hanging fruit than trying to sort out the . First, the more common L. aestivus, shown next, which does not appreciably turn green and is found with true fir and hemlock. Secondly, the dingy coloured L. aurantiosordidus, also below, found with spruce.

Lactarius deliciosus group member © Steve Trudell


Lactarius aestivus

This group member is our most common species, described from Washington, with bright orange colours and latex. It grows with true fir and hemlock but does not turn appreciably green.

Lactarius aestivus © Danny Miller


Lactarius aurantiosordus

This small-ish spruce species is dingy orange, with dingy orange latex. It is a California species whose DNA has occasionally been found in Oregon and BC. Other spruce species without names so far will probably (hopefully) be larger, with brighter cap and milk colouring.

Probable Lactarius aurantiosordidus © Debbie Viess


Lactarius rubrilacteus

This very common species, described from Oregon, has red "blood" or latex, and is an especially cool species. It is a dull orange colour and can turn considerably green. It is a conifer species, under Doug fir and pine, at least.

Lactarius rubrilacteus © Steve Trudell


Lactarius barrowsii

This rare mushroom is very pale, almost white, but may have orange and green splotches. Its milk is red. It has been found in Idaho, but is more common in the SW (Arizona, Colorado) under pine.

Lactarius barrowsii © Dimitar Bojantchev

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