Danny’s DNA Discoveries – Lactarius of the PNW
Introductionabundant common uncommon rare - colour codes match my Pictorial Key and are my opinions and probably reflect my bias of living in W WA. Rare species may be locally common in certain places at certain times.
Click here to download the FASTA data of all my DNA sequences
Read my introduction to Russula for an explanation of what makes Russula and Lactarius unique among gilled mushrooms. Lactarius are notable for bleeding a latex, often called a milk, when broken, especially from the gills. The milk is usually white, but may be yellow, orange or red (or rarely blue!) and even change colours while you watch. They look somewhat like Russulas, but unfortunately, there's a lot more variety of statures, so you can't as easily learn to recognize a Lactarius on sight as you can a Russula - you may need to break it to see the latex (which may be scanty or, if the mushroom has dried out, even lacking). Not every "bleeding" mushroom is a Lactarius, though. The most common other "bleeders" are much smaller and more delicate Mycenas. Even small Lactarius are not very delicate (although they are fragile, as explained under Russula).Some common features of Lactarius that might help you spot one are a frequently zoned cap, scrobiculate stem (covered with large, round pits of pigment), and a inrolled cap margin that might be bearded with hairs. Some species don't have any of these features, though. It's very common for them to taste acrid, or somewhat hot like a hot pepper, just like some Russulas. Not many other mushrooms besides Russula and Lactarius have that taste.
Normally there is a subgenus/clade named after the genus, so there "has been/should be/will be again" a clade "Lactarius", but right now, the species that have been placed in clade "Lactarius" are not actually related to each other, so some fixing and shuffling of species will have to be done before that clade name can be properly used.
Deliciosi Clade - Coloured Milk - click to expand
This clade has coloured milk, instead of the whitish milk that every other Lactarius will have (although the white milk in other clades might turn yellow in a matter of seconds or eventually stain tissue purple). Usually you'll find orange or red latex, and the mushrooms themselves are usually orange or red too, often with a beautiful, prominent green staining. The east coast has a common blue Lactarius that bleeds blue milk and I'm very jealous. Most of them taste rather mild, or at most slightly bitter or slightly hot.
Species mentioned: Lactarius deliciosus, deliciosus var. areolatus, deliciosus var. olivaceosordidus, deliciosus var. piceus, aurantiosordidus, deterrimus, aestivus, rubrilacteus, barrowsii
Lactarius 'deliciosus' group - first the many orange species with orange latex. (Orange and white species with red latex will follow).
I'm finally getting a handle on how many species we have in this group. We don't have the real L. deliciosus, nor do we have the real L. deterrimus as has been reported (the latter being a sister species to L. aurantiosordidus, below, which it probably has been mistaken for). All our varieties will probably need their own species name and won't continue to be considered varieties. As a group, the L. deliciosus group mushrooms usually have zoned caps that are orange with orange latex that may turn reddish or purplish 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 get somewhat bitter (like black pepper) and some may show a bit of the hot pepper acrid taste so common in other clades. When known, I will describe how a species differs from this general description.
Lactarius deliciosus var areolatus ID - from Idaho, possibly the most common species inland at high elevations in the Rockies usually near spruce or pine. It seems rare nearer the coast. The latex can be hard to find and the cap may crack, but both these features can be explained by growth in dry inland habitats (which may also dull the colours). It needs its own name, but L. areolatus is already taken. It appears we know its DNA from a couple of collections used by Nuytinck in his official 2007 study of the species found in North America. Microscopically, you can identify it by somewhat larger spores than most and a lack of large pleuromacrocystidia on the gill faces. No local photo.
Lactarius deliciosus sensu Hesler & Smith (?? conifer version) - In their important 1979 work on this genus, H&S thought the European L. deliciosus occured here, but the DNA of our species shows it probably needs its own name and can't even be considered a variety of that. The DNA was very confusing - a couple dozen sequences were all scattered around the tree up to 3% different from each other, much higher than the usual 0.5%. However, I recently found a couple of sequences with more than one nucleotide at 4 or so key locations, showing that all the sequences fell somewhat neatly into two piles, 1% apart from each other, with most members of each pile within 0.5% of each other once you account for the ambiguities. Nuytick's 2014 study where he described L. aestivus (below) and provided sequences of L. deliciosus sensu H&S only showed examples from one of the piles, so I am labeling this one as the official H&S concept. I don't have tree information for most of these sequences (one was from pine), but it is usually reported from spruce and pine. We need more collections from other conifers as I suspect this may not be restricted to spruce and pine. The spores are somewhat smaller than 'var. areolatus' above and it is more common near the coast. Now keep reading.
Lactarius aff deliciosus sensu Hesler & Smith (pine version) - A distinct clade almost 1% different than the former clade also emerged, and every collection appears to be from 2- or 3-needle pine. Since the former collections didn't have strongly associated tree data and since this clade is distinctly different genetically, for now I am allowing for the fact that L. deliciosus sensu H&S may need to be split into two varieties or subspecies.
Lactarius deliciosus sensu H&S and the sister pine clade © Ann Goddard and Daniel Winkler
Lactarius cf deliciosus var. piceus EU - this spruce species has pleuromacrocystidia but smaller spores than the duller orange L. aurantiosordidus (below) and is reported as being L. deliciosus var. piceus from Europe, but I have my doubts that it is what it is. Not only has every other species turned out to be different than its European counterpart, H&S themselves seemed unsure about this identification. We have no EU DNA to compare with, nor do we have any local DNA yet. We are badly in need of sequenced collections to see what this species really is. No local photo.
Lactarius aestivus WA - This group member is our most abundant species, described from Washington, and easy to recognize (except for a possible southern lookalike described next) with bright orange colours and latex. It grows with true fir and hemlock but does not turn appreciably green.
Lactarius aestivus © Danny Miller
Lactarius 'vesper PNW01' - This lookalike species is not sister to L. aestivus, nor is it inside the clade of confusing L. deliciosus group species mentioned above. It looks a lot like L. aestivus, (bright orange with only a little green staining), but the milk, instead of staying bright orange for a while, quickly turns intensely reddish-orange. It was found once in Southern Oregon and three times in WA where fir was the tree common to two collections (the same habitat as L. aestivus).
Lactarius 'vesper PNW01' © Jonathan Frank and Michael Beug (3 images)
Lactarius aurantiosordidus WA (deliciosus var. olivaceosordidus OR) - This small-ish spruce species is dingy orange, with dingy orange latex and usually a green cast to the cap. It is a California species whose DNA has uncommonly been found in Oregon and BC. Other spruce species without names so far will probably (hopefully) be larger, with brighter cap and milk colouring. The type sequence of L. deliciosus var. olivaceosordidus was recently discovered to be the same as this species, and not a variety of L. deliciosus.
Probable Lactarius aurantiosordidus © Debbie Viess
Lactarius rubrilacteus OR - This abundant 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 NM - This rare mushroom is very pale, almost white, but may have orange and green splotches. Its milk is red. It has been found in either Washington or Idaho (the report is conflicting, so perhaps near the border), but is more common in the SW (Arizona, Colorado) under pine where it was described from NM. It is probably an inland species.
Lactarius barrowsii © Dimitar Bojantchev
Russularia Clade - Candy Cap relatives - click to expand
Candy caps are species of Lactarius that smell and taste like maple syrup when dried. They make excellent desserts, something unusual for a mushroom. To eliminate the more typical mushroom flavours from the food, the mushrooms are powdered and mixed into a fat - like cream or butter and used to make ice cream or popcorn or cookies. Unfortunately they are hard to identify because they do not smell or taste that way when fresh (some people use a lighter to burn them to see if they can coax a sweet smell out of them in the field for identification purposes). There also exists an Oregon candy cap "truffle" in this clade.Mushrooms in this clade are usually small, with caps about 5 cm wide and stems <1 cm thick, but there are exceptions. They are usually orange-brown to red-brown and bleed a white milk. They are mostly mild or only slightly hot tasting (with one notable exception). (A few small brown or greyish-brown Lactarius that are not in this clade either have a velvety cap or are very slimy all over).
Species mentioned: Lactarius rubidus, fragilis, camphoratus, subviscidus, substriatus, subflammeus, aurantiacus, luculentus var. luculentus, luculentus var. laetus, tabidus, theiogalus, thejogalus, alpinus var. alpinus, alpinus var. mitis, occidentalis, carbonicola, lepidotus, rufus, atrobadius, hepaticus, xanthogalactus, chrysorheus, vinaceorufescens
Lactarius rubidus OR - Our local common candy cap species (described from Oregon) has a dry cap, watery-white latex (like skim milk instead of whole milk), and completely mild taste. The cap is somewhat of a dull orange-brown. It will smell like maple syrup when dried, but several almost identical looking species don't. Other species around the world, like L. fragilis and L. camphoratus, look very much the same but are not found here.
Lactarius rubidus © Noah Siegel
There are many candy cap lookalikes. Do not expect to be able to learn to tell them apart by my descriptions below, which are incomplete, as the differences are subtle and often microscopic.
Lactarius subviscidus WA - This lookalike, described from Washington, has a slightly sticky cap, thick white milk (like whole milk) and slowly turns slightly hot when chewed. The colour is sometimes a deeper orange- or reddish-brown.
Lactarius subviscidus © Ed Barge
Lactarius substriatus WA (= L. subflammeus OR?) - This is also slightly peppery after a while and can be viscid and somewhat striate on the cap margin. Its milk may eventually stain itself and other mushroom tissue yellow. The colouration is sometimes very close to that of a real candy cap. L. subflammeus was said to differ by its milk not having any yellow staining properties, but if the species are the same, the yellow staining may have been overlooked or not be constant. The type of L. subflammeus (a Smith species from Oregon) has the same sequence as some Smith collections that he labelled L. substriatus. We don't have his type sequence of L. substriatus from Washington yet, so we don't know for sure, but they appear to be the same species.
Lactarius 'substriatus PNW02' - Victoria BC, southern OR and CA has a second species in this complex (a species Cathy Cripps called "sp. 2"). It is paler orange than L. substriatus, smaller (caps around 2.5cm across) and grows in large groups near Doug fir, fir or Garry oak.
Lactarius substriatus © Marty Kranabetter, L. 'substriatus PNW02' © Jonathan Frank and Michael Beug
Lactarius luculentus OR - L. luculentus var luculentus, from Oregon, has an off-white spore print, a viscid cap and a slightly bitter and/or slightly peppery taste. It has very similar colouration to the others, but is uncommon. It is found under Douglas fir. Its DNA has been found in WA as well.
Lactarius luculentus var luculentus © Buck McAdoo
L. luculentus var. laetus WA - L. luculentus var. laetus, from WA under spruce and probably other conifers, has a pure white spore print, a somewhat viscid cap and slightly bitter taste. It is usually the brightest orange species. Colorado sequences supposedly of var. laetus are somewhat different, so the Rockies may have a third, as yet undescribed variety. Lactarius aurantiacus is the name of a European mushroom that we have incorrectly used for some of our false candy caps in the past, especially for L. luculentus.
Lactarius luculentus var laetus © Gabriela D'Elia
Lactarius tabidus EU (=L. theiogalus EU, = L. thejogalus EU) - this species seems to have a dry cap and duller colours than the others, possibly even brown tones like Lactarius occidentalis, which it is probably most like, even in the sense that it is found near alder (and maybe other hardwoods). Supposedly it is slowly acrid tasting. It is also very much like many of the above candy cap lookalikes.
We were starting to believe that the few reports of this European candy cap lookalike were mistaken, but then we found one in OR confirmed by DNA, although we only got ITS1 and ITS2 separately and were missing some areas (most collections have 2 different alleles in 5.8s with an indel in one of them, which makes it extremely difficult to obtain a full ITS sequence). With only 2 fragments of ITS DNA, we could not make a complete comparison. Then a collection was found in WA and Matt got an entire ITS sequence through a lot of careful hand editing, and it is a great match to almost 100 EU sequences (averaging a couple of indels as the only differences). The DNA was also found in Alaska so it could be widespread around the area, just rare. Lactarius theiogalus is the older name, but nobody is sure what mushroom that refers to (this is only one possibility) so that name won't be used any more and the newer name L. tabidus, which is well defined, is replacing its use here.
Lactarius tabidus © Richard Morrison
Lactarius alpinus NY var mitis ID - differentiated from the other small, orange candy cap relatives by a cap that may be finely cracked or scaly. It may also have an umbo. The taste is mild and it grows under alder. Described from Idaho, this variety appears to be a distinct species in the Piperites in need of a new name, and not a variety of L. alpinus, as specimens from other places in the Rockies (Montana and Colorado) provided by Cathy Cripps have DNA that is quite different than var alpinus.
Lactarius alpinus NY var alpinus NY - The type variety is acrid tasting. It is said to occur here but so far the DNA has only been found in Newfoundland, Europe and Alaska.
We really need examples of both of these to figure out what they are and how to identify them confidently. These are probably the least understood candy cap relatives.
unsequenced Lactarius alpinus var. mitis from Oregon © Edward Barge
These species look different enough from the candy cap that they are easier to identify and harder to confuse with the candy cap.
Lactarius occidentalis WA - This alder species is dull brown to perhaps olive-brown on the cap and somewhat orange on the stem. It has a mild taste. Described from Washington. It is probably most easily confused with the rarer Lactarius tabidus, above.
Lactarius carbonicola MI is a similar east coast species, perhaps in the Russularia, perhaps not. It was reported once from Idaho and needs specimens. It is somewhat brick red with watery milk, and not much is known about its tree associations except it's sometimes found on burned ground).
Lactarius lepidotus WA is a similar (perhaps in the Piperites and not in the Russularia) drab little grey-brown mushroom found only at Mt. Rainier under alder so far. It has a scaly cap. We need collections to analyze.
Lactarius occidentalis © Danny Miller
Lactarius atrobadius OR - Often mistaken for the European conifer species L. hepaticus, this alder species described from Oregon has a viscid, very dark blackish-red cap and a mild taste. It has the darkest cap in the group (L. occidentalis probably has the second darkest cap). We have the OR type sequence and the DNA has been found in boreal BC as well.
Lactarius hepaticus EU - This European conifer species has been rarely reported locally (mostly in Idaho), but we need collections to verify that they aren't really just L. atrobadius. It is said to have a dry cap and slightly acrid taste, with milk that slowly stains yellow.
probable Lactarius atrobadius © Noah Siegel
Lactarius rufus EU - This European conifer species can get larger than most other species, is a brick reddish colour, but most importantly is exceedingly hot tasting and can be identified on that basis alone, if you're brave enough to try it.
Lactarius rufus © Steve Trudell
Lactarius xanthogalactus CA - This large Lactarius doesn't look like it belongs in this clade, so it is also keyed out under the "milk that turns yellow" group, but it appears to be related. It has an orange cap, a white stem and white milk that rapidly turns yellow. It can taste somewhat bitter or acrid. It has mistakenly been called L. chrysorheus and L. vinaceorufescens. It's a southern species from California also found in Oregon (locally common there, but rare elsewhere), under oak and Doug fir and in mixed forests.
Lactarius xanthogalactus © Danny Miller
Two small Lactarius may resemble the Russularia, but are actually in the Piperites: L. glyciosmus (grey birch species that smells like coconut) and L. pseudomucidus (dark grey cap and stem contrasted with white gills, very slimy everywhere).
Plinthogalus Clade - Lactarius fallax group - click to expand
Members of this subgenus have velvety caps. The most common and obvious ones are very velvety dark brown mushrooms. Rarely, we find a minutely velvety pale capped mushroom in this subgenus.
Species mentioned: Lactarius fallax, fallax var. concolor, pallidiolivaceus, fumosus var. occidentalis
Lactarius fallax WA - Mostly mild tasting with a beautiful brown velvety, suede cap. Species are not separable, as previously thought, by the presence of marginate gills (dark coloured edges), so var concolor and var fallax (both described from Oregon) are not valid genetic varieties, only forms. The types have identical ITS sequences. Lactarius fallax has been verified from BC, WA and ID.
Lactarius aff fallax - There is a sister species that also can have either pale or coloured gill edges, found in WA and CA. We don't know how to tell the two species apart yet, but I am investigating whether this sister species might have more caramel brown colours that aren't quite as dark as the real thing.
Lactarius fallax © Steve Ness, L. aff fallax © Daniel Winkler
Lactarius pallidiolivaceus OR - A species described from Southern Oregon under pine, but it's also found in California with other trees. It is in this subgenus, because if you look closely, the cap is minutely velvety under a hand lens. It is pale orange-olive-grey with a very tough stem and scanty milk that stains tissues dark. Most collections are mild tasting but one was very acrid (perhaps it was misidentified).
This was originally described as a variety of Lactarius fumosus, Lactarius fumosus var. occidentalis, which it is indeed fairly closely related to. We have that type sequence. It was subsequently elevated to its own species.
This is the largest clade, so I will break them up into smaller groups. Most of them are at least somewhat peppery tasting (and most peppery species are in this clade).
Milk that quickly turns yellow - click to expand
Within 10 seconds or so, the milk of these species will turn from white to yellow before your eyes, as shown above.
Species mentioned: Lactarius scrobiculatus var. canadensis, payettensis, resimus, resimus var. regalis, xanthogalactus
Lactarius scrobiculatus EU var canadensis PQ - This conifer species is genetically different from the European type variety. It is yellow with a bearded cap margin and yellow scrobiculate stalk. Originally called Lactarius payettensis var. canadensis, it was quickly moved to be a variety of L. scrobiculatus. But that leaves the mystery of what the Idaho species Lactarius payettensis var. payettensis is.
Lactarius scrobiculatus var canadensis © Steve Trudell
Lactarius resimus EU group - This mixed forest European species is whitish capped, with a bearded margin and somewhat scrobiculate stalk. DNA matching that from Europe has been found in BC so far. It, and its variety var regalis with larger spores have been reported elsewhere around the PNW but we don't know if the variety has distinct DNA or not.
An unamed sister species under pine has been found and sequenced from OR and AZ. Other unique sequences have also been found but not much is known about them yet.
Lactarius alnicola is a related yellow capped mixed forest species, but its milk does not quickly turn yellow, so it will be described later.
Lactarius aff resimus AZ+OR © Jonathan Frank
Lactarius xanthogalactus CA - This species described from mixed forests in California (especially Doug fir and oak) is probably in clade Russularia (it has no bearding nor scrobiculation) but has an orange cap and a white stalk. It also occurs in Oregon, locally common, but rare elsewhere.
Lactarius xanthogalactus © Danny Miller
There are isolated, unconfirmed sequences of local DNA of related species so we probably don't know the whole picture yet.
Purple staining Lactarius - click to expand
This reaction may take a few minutes, but the milk will stain the mushroom's own tissues purple. The milk itself doesn't turn purple, nor will the milk turn anything purple except other parts of itself. Most, except for L. representaneous and L. cascadensis appear to form a clade of related species. The other two are of unclear affiliation.
Species mentioned: Lactarius pallescens, californiensis, montanus, cascadensis, aspideus, aspideoides, salicis-reticulatae, pallidomarginatus, representaneus
Lactarius pallescens ID - This conifer species, described from Idaho, is white and KOH will turn the flesh yellow. The stem is rather viscid.
Lactarius montanus ID - This conifer species, also described from Idaho, has a more greyish cap, sometimes with orange or lilac tints. KOH turns the cap green. ITS DNA between BC and CO can differ by up to 6bp, so it's possible this is a species complex.
Lactarius californiensis CA - A southern species from OR and CA with similar colours to L. montanus (greyish-orange) but with the yellow KOH reaction of the white L. pallescens (which it is more closely related to, not to L. montanus). We have DNA from OR that most likely represents this.
Lactarius pallescens © Michael Beug, L. montanus © A and O Ceska, L. californiensis © Jonathan Frank
Lactarius cascadensis OR - Described from Oregon and also collected in WA and ID more than 50 years ago and never photographed in colour (or at all since 1946?) until now, it has a lilac grey/cinnamon cap that is zoned. It is large, with gills the colour of the cap and a mild taste found under alder. It has watery-white latex that stains tissues pink/purple and a scrobiculate stem. We had the ITS1 sequence of the type collection, but not ITS2, but now these modern collections provide some of ITS2. It is closely related to the purple stainer L. representaneus, but not the other purple stainers.
Lactarius cascadensis © Michael Beug
Lactarius aspideoides VT - this group of purple staining species is recognized by a yellow cap with a smooth, unbearded margin and non-scrobiculate stem. This east coast mixed forest species has a viscid stem.
Lactarius salicis-reticulatae EU - a very similar (if not identical) alpine willow species, with ITS DNA extremely close to L. aspideoides. It is the only species of this group verified from the west so far (from Wyoming). We need local PNW collections outside of alpine willow areas to see if this is indeed the proper name of our species or if other species in this group are here.
Lactarius aspideus EU/pallidomarginatus CO - The very similar (but with a dryer stem) European L. aspideus has been reported from here and the almost genetically identical L. pallidomarginatus has been described from Colorado. No proof from the PNW yet of either.
Lactarius salicis-reticulatae © Edward Barge
Lactarius representaneus EU - This European conifer species is also yellow, but it is bearded with a scrobiculate stem. DNA has been found in WA so far, and it's reported from elsewhere in the PNW. It does not reliably appear in the same clade as the others, which makes it interesting that it is the only bearded species.
Lactarius representaneus © Ian Gibson
Other Lactarius - click to expand
Species mentioned: Lactarius glyciosmus, pseudomucidus, occidentalis, lepidotus, alpinus var. mitis, controversus, pseudodeceptivus, argillaceifolius var. megacarpus, kauffmanii, kauffmanii var. sitchensis, mucidus, caespitosus, glutigriseus, affinis, trivialis, flexuosus, pseudoflexuosus, circellatus var. borealis, rufus, hysginus, necator, turpis, olivaceoumbrinus, sordidus, pubescens var. betulae, torminosus var. nordmanensis, subvillosus, olympianus, zonarioides, alnicola, payettensis, vietus
This is a separate genus now, of mainly tropical species. We don't have any confirmed species in the PNW, although the European Lactifluus volemus has been rumoured from far northern Alberta and BC. It is big and orange with a dry, minutely velvety cap and a fishy odor.
Figure out how many species we have in the Lactarius deliciosus group, and give them names.
Figure out the L. substriatus complex and which is the real one, and verify it is the same as L. subflammeus.
Name our L. luculentus var. 'laetus' if it is in fact distinct from the real thing.
Get official sequences of L. alpinus and its varieties.
See if L. hepaticus actually occurs in the PNW.
Figure out how to tell the two species of L. fallax apart
Get sequences of L. carbonicola and L. lepidotus
Verify what sequences of L. alnicola and L. resimus are and document the unnamed species sequences in this group.
Figure out which species are in the PNW of the L. aspideus group (L. aspideoides? L. pallidomarginatus?)
Figure out if we have an additional sister species of L. glyciosmus.
Get sequences of L. sordidus and figure out if it's here.
Figure out if the varieties of L. pubescens and L. torminosus are distinct, and if we have a third species.
Determine if we have L. hysginus and what it is and how many varieties we have.
Get sequences and specimens of L. payettensis
Figure out what L. pseudodeceptivus is.
Sort out L. mucidus and its varieties, L. caespitosus and L. glutigriseus and see if we have additional species.
Figure out if there are additional species in the L. affinis/L. trivialis complex.
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