Lactarius

Introduction

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.

abundant 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.

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 that often stain green. (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 (=var. deliciosus sensu Hesler & Smith?) (conifer version) - In their important 1979 work on this genus, H&S thought the European L. deliciosus occured here, but that DNA has never been found here. Our many species are not even varieties of L. deliciosus but probably all need their own species names. This entry represents what most people thought H&S were referring to when they called something L. deliciosus var. deliciosus. However, the type sequence of their var. areolatus turned out to match what people thought was H&S's concept of var. deliciosus.

Note that ITS sequences of this were 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 she described L. aestivus (below) provided sequences of L. deliciosus sensu H&S but they were this variety, var. areolatus. She provided sequences of what she thought was var. areolatus from UT and CO. I don't know what that species really is, and it has not been found yet in the PNW. 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 supposedly on the large size for this variety.

Lactarius 'deliciosus PNW11' (=var. 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 this clade may need its own name.

Lactarius deliciosus var. deliciosus EU - we still need to know what species H&S called by this name, if it's not one of the above, because they certainly weren't calling it by the right name.

Lactarius deliciosus var. deterrimus EU - we still need to know what species H&S called by this name, if it's not one of the above, because they certainly weren't calling it by the right name.

Lactarius cf deliciosus var. piceus EU - we still need to know what species H&S called by this name, if it's not one of the above, because they certainly weren't calling it by the right name. In this case, though, we have no EU DNA to compare with. This spruce species has pleuromacrocystidia like the duller orange L. aurantiosordidus (below) but smaller spores than it.

Lactarius deliciosus var. areolatus © Ann Goddard, L. 'deliciosus PNW11' (pine clade) © Daniel Winkler

Lactarius aestivus WA - This group member is our most abundant species, described from Washington, and easy to recognize (except for the lookalike described next) with bright orange colours and latex. It grows with true fir and hemlock but does not turn appreciably green.

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 aestivus © Danny Miller, Lactarius 'vesper PNW01' © Jonathan Frank and Michael Beug (2 images)

Lactarius aurantiosordidus WA (L. 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 has pleuromacrocystidia. 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

Red Latex

Lactarius rubrilacteus OR - This abundant species, described from Oregon, has red "blood" or latex, and is an especially cool species. It has a dull orange zoned cap and can turn considerably green. It is a conifer species, under Doug fir and pine, at least.

Lactarius 'barrowsii PNW13' - has a pale unzoned cap with orange and maybe green splotches. Its milk is red. It has been found in either Washington or Idaho (the report is conflicting, so perhaps near the border). That ITS sequence is 2% different than the NM type sequence, but so are AZ and MT sequences from collections under pine near where it was described from NM. They match ours better than the type. I don't know if there's more than one species here or if something's wrong with the type sequence.

Lactarius rubrilacteus © Steve Trudell, Lactarius 'barrowsii PNW13' (from MT) © Ed Barge

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, cuspidoaurantiacus, occidentalis, carbonicola, lepidotus, rufus, atrobadius, badiosanguineus, 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.

unsequenced Lactarius rubidus © Noah Siegel

There are many confusing candy cap lookalikes. Hardly anybody knows how to tell them all apart and that is partly because the descriptions of two of them appear to have been swapped for decades, complicating our understanding of them. Here is what I have been able to sort out.

Lactarius subviscidus WA - all the literature calls collections that look like this Lactarius substriatus, but the type sequence shows that mushrooms matching the official description of L. substriatus are really L. subviscidus, so all subsequent literature may have gotten it backwards. Here is the official description of L. substriatus which we should probably start calling L. subviscidus instead: a somewhat viscid cap, white milk that slowly stains yellowish, a taste that turns slowly acrid, and a bright orange cap with a paler rim that can be striate. Unfortunately, this means that L. subviscidus is the one that is striate, not L. substriatus.

Lactarius substriatus WA (= L. subflammeus OR) - very similar. Here is the official description of L. subviscidus which we should probably start calling L. substriatus based on the mix-up described above: it has an opaque cap that is more uniformly a deep, dark orange-reddish brown, usually lacking striations (this mix-up means L. subviscidus is the species that is striate, not L. substriatus). Like L. subviscidus, L. substriatus is also somewhat viscid and slowly tastes somewhat acrid. The milk will never turn yellow (in the description of L. subflammeus) or the milk will at most stain paper yellow overnight (in the description of L. subviscidus which is probably describing L. substriatus). The holotype of L. subflammeus (a Smith species from Oregon) has the same sequence as the holotype of L. substriatus, and it makes sense that the two are the same species given the very slight differences between them. L. subflammeus has always been described as almost identical to L. subviscidus, but remember, since the descriptions are backwards, L. subflammeus is actuially the same species as L. substriatus. It should be noted that a paratype sequence of L. subflammeus was not the same species as the holotype, but it turned out to be L. luculentus var. luculentus. I hope that doesn't matter.

Lactarius subviscidus © Ed Barge and Yi-Min Wang, L. substriatus © Ed Barge

Lactarius PNW02 ('acrid orange') - known from Victoria BC through California (a species Cathy Cripps called "sp. 2"). It is paler or duller orange than L. substriatus and L. subviscidus and is probably more quickly acrid than both. Otherwise, it is similar, with a somewhat viscid, non-striate cap, and white milk that does not stain yellow. It is smallish (caps around 2.5cm across) and grows in large groups near Doug fir, fir or Garry oak. It is known in Mushrooms of the Redwood Coast as 'acrid orange', where they explain that it was going to be called Lactarius desjardinii, but that name is now taken so it needs a new name. One of Smith's early collections of Lactarius luculentus var. luculentus turned out to be this species, but that species is not usually acrid.

Lactarius PNW02 © Jonathan Frank and Michael Beug

Lactarius luculentus var. luculentus OR - Lactarius luculentus var. luculentus from Oregon is another viscid capped lookalike with white milk, but with a slightly bitter taste (not usually acrid). This variety has a darker orange cap usually without striations and an off-white spore print. It is found under Douglas fir. We don't have a type sequence yet, but I think I know it's sequence. That DNA has been found in WA as well. One hitch is that an official Smith collection (but not a type) turned out to not be what I think of as this species, but PNW02 instead. We're getting the type sequenced to sort this out.

L. luculentus var. laetus WA - L. luculentus var. laetus, from WA under spruce and probably other conifers, is a variety with a brighter orange cap (brighter than PNW02 and not as dark as L. subviscidus and especially L. substriatus). This variety also has a pure white spore print. Otherwise it has the same viscid cap and slightly bitter taste. We have the type sequence and many matching local sequences. 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 in the past for this and other lookalikes.

Lactarius luculentus var luculentus © Buck McAdoo, iNaturalist user ellenkr and Sharon Squazzo

Lactarius luculentus var laetus © Gabriela D'Elia and iNaturalist user method1221

Lactarius tabidus EU (=L. theiogalus EU, = L. thejogalus EU) - this species has a dry cap (like the candy cap) and somewhat 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). It has white milk that is slowly acrid tasting. Sometimes it will be somewhat bright orange and hard to differentiate from the slightly viscid capped bright species.

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 'carbonicola PNW12' - we had one surprise sequence from Idaho of a collection that is papillate with strongly decurrent gills that matches several east coast sequences claiming to be Lactarius neotabidus MI or the similar but older Lactarius carbonicola MI, but we have both type sequences, and these collections are neither, but somewhat in between. What are all modern collections different than either type? Our sequences only differ by 2% in ITS1 from the type sequence of L. carbonicola but is an exact match in ITS2. Perhaps that's not surprising, as L. rufus' ITS sequence differs from that of at only in ITS2. Note that an east coast collection that matches our ITS (but not the type's ITS) is not papillate. Our species has been found with hardwoods like willow, cottonwood, aspen, and alder. Lactarius oculatus NY should be investigated too, as that mushroom is described similarly.

Lactarius tabidus © Richard Morrison (2 images), L. 'carbonicola PNW12' © Edward Barge

The following look like Russularia, and probably are, but my tree cannot place them in any subgenus with high support.

Lactarius cuspidoaurantiacus Mexico (=Lactarius alpinus NY var mitis ID) - differentiated from the other small, orange candy cap relatives by a dry cap that may be finely cracked or scaly. It may also have an umbo. The taste is mild and it grows under alder. The type sequence of var. mitis and sequences of specimens from Oregon, Montana and Colorado have DNA that is quite different than var alpinus, so it needed elevation to species. Fortunately, a species was more recently described that has identical ITS and appears to be the same thing, so now we do have a valid name for this, Lactarius cuspidoaurantiacus.

Lactarius alpinus NY var alpinus NY - The type variety is also scaly capped but brighter yellow and supposedly acrid tasting. It has been found and sequenced from ID. The sequences we have are not near var. mitis in my ITS tree.

Lactarius lepidotus WA is closely related to L. alpinus var. mitis, whatever subgenus that is in, and a drab little grey-brown mushroom found only at Mt. Rainier under alder so far. It also has a scaly cap. We have a WA paratype sequence and one ID collection is 3 bp and 1 indel different.

Lactarius cuspidoaurantiacus, L. alpinus var. alpinus, and L. lepidotus © Edward Barge

Other Russularias

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 has a dry, dull brown to perhaps olive-brown cap, without orange tones, but is 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, with brighter colours, and L. badiosanguineus, below, sometimes even darker. We have the holotype ITS sequence and matching local sequences.

Lactarius badiosanguineus EU (=L. atrobadius OR) - this mild tasting alder species sometimes has a distinct blackish-reddish-orange cap (in its typical form) but other times a brighter reddish-orange cap (like a mild tasting L. substriatus or L. luculentus), making it a candy cap lookalike. It appears that Hesler and Smith had not heard of L. badiosanguineus and called dry capped inland collections of L. badiosanguineus by the EU name L. hepaticus. When they found viscid capped collections in the wetter coastal areas, they redescribed it as L. atrobadius. The OR type sequence of L. atrobadius and EU type area sequences of L. badiosanguineus are practically identical. Locally, it has been sequenced from boreal BC, OR, and ID.

Lactarius hepaticus EU - This European conifer species has been rarely reported locally (mostly in Idaho), but those reports are probably collections of L. badiosanguineus. It has a dry cap and slightly acrid taste, with milk that slowly stains yellow. I doubt it's actually present here.

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.

I do not have strong support for this species being in the Russularia. It does not look like it belongs here. But I can't place it anywhere for certain.

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.

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

Piperites Clade - everything else

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 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, olivinus, scrobiculatus var. montanus, leonis, tuomikoskii, alnicola, payettensis, resimus, resimus var. regalis, resimus var. intermedius, aquizonatus, auriolla, xanthogalactus

Lactarius 'tuomikoskii PNW14' (Lactarius scrobiculatus EU var. canadensis PQ misapplied) - yellow with a bearded cap margin and yellow scrobiculate stalk. The milk turns quickly and dramatically yellow. This has long erroneously been called L. scrobiculatus var. canadensis PQ. However, H&S lumped 2 or 3 species into that concept, and west coast collections are different than the PQ type collection. The var. canadensis type sequence only matches sequences from PQ, Europe, China and MT. Also, it is not a valid varietal (too distant) and now has its own species name, Lactarius olvinus EU. Our abundant species is very close to Lactarius leonis EU and even closer to Lactarius tuomikoskii EU, but the 3 bp ITS differences are usually enough to indicate a distinct species in this group. Alaska seems to have the real L. tuomikoskii.

Lactarius scrobiculatus var. montanus CA - a cream coloured interior species. It needs elevation to species. One OR sequence matches the CA type sequence. No modern photo. I'm not sure how to distinguish it.

Lactarius alnicola ID (=Lactarius scrobiculatus EU?) - this similar mushroom does everything a little less dramatically than PWN14. The milk turns slowly yellow, the yellow cap may be zoned and is only somewhat bearded and the stem is only somewhat scrobiculate. Although named after alder (alnicola means "alder loving"), it can be found with both hardwood and conifer trees. It is pretty rare, mostly restricted to the interior. The much older species Lactarius scrobiculatus has ITS sequences within 3 bp of L. alnicola. For now I am keeping them separate, but it may be decided that the two are synonyms in which case we will start using the older name.

Lactarius payettensis ID - This lookalike has slowly yellowing milk but a strongly bearded cap that is unzoned and a strongly scrobiculate stem. It is usually, smaller, paler, and maybe more olivaceous than L. alnicola. It was described with spruce, fir with alder and aspen present, but recently found with only spruce and alder present. It too is an interior species. We have the type sequence and a modern ID collection.

Other similar species exist nearby. Lactarius aquizonatus EU has been found in northern BC and Alaska. Lactarius auriolla EU DNA has been found in a soil sample in BC.

unsequenced Lactarius 'leonis PNW14' © Steve Trudell, Lactarius alnicola © Ed Barge (2 images)

Lactarius payettensis © Ed Barge (2 images)

Lactarius resimus EU - 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.

Lactarius 'resimus PNW08' - an unnamed lookalike that is more common, found under pine, has been found and sequenced from OR and AZ

Lactarius 'resimus PNW08' © Jonathan Frank (2 images)

Lactarius xanthogalactus CA - This species described from mixed forests in California (especially Doug fir and oak) has weak support for being in the Russularia instead of the Piperites. 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

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, cordovaensis, 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 the type sequence and a collection from OR.

Lactarius pallescens © Michael Beug, L. montanus © A and O Ceska, L. californiensis © Jonathan Frank

Lactarius cordovaensis AK (=Lactarius cascadensis OR) - L. cascadensis was 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. Our modern sequences are 2 chunks of 2 bp different than the type sequence. However, the type sequence of L. cordovaensis from Alaska has an identical sequences to our modern WA sequences, so the two species may be the same. They were described in the same publication, with L. cordovaensis a few pages earlier, if that matters. According to Smith, who described them both, L. cordovaensis has a viscous milk-white latex (as opposed to whey-like), an odor somewhat resembling that of L. camphoratus when dried, orange-tan gills which become paler in age (as opposed to cinnamon-buff), and slightly smaller spores. In the key, he differentiates the two by saying L. cordovaensis has a thicker ixocutis. These are not big differences. Our WA collection had thick milk like L. cordovaensis but larger spores like L. cascadensis. Since we found a collection with some characters of each, I think the two species are the same and if so, the name L. cordovaensis is in more common usage and may win out as the official name.

Lactarius cascadensis © Michael Beug (sequenced and unsequenced)

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. One WA collection has an ITS sequence 4 bp different from both L. aspideoides and L. salicis-reticulatae, but not being from alpine willow, it best matches L. aspideoides.

Lactarius salicis-reticulatae EU - a very similar (if not identical) alpine willow species, with ITS DNA extremely close to L. aspideoides (just a couple differences). It was the only species of this group verified in a study from the west (from Wyoming). Either this is a newer synonym of L. aspideoides, or the 2 cannot be differentiated by ITS, or PNW collections are yet another distinct species without a name yet. Probably, our collections should be called L. aspideoides.

Lactarius aspideus EU/pallidomarginatus CO - The very similar (yellow but with a dryer stem) European L. aspideus has been reported from here and the almost identical (in ITS) L. pallidomarginatus (with a brownish-tan cap) has been described from Colorado. No proof from the PNW yet of either. However, keep reading.

Lactarius 'aspideus PNW15' - this one OR collection is in the Lactarius aspideus/pallidomarginatus complex, but not quite matching either. It's identity needs to be determined. It was found with aspen, maple and willow, and was almost white like L. pallescens.

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 aspideoides © Danny Miller, Lactarius 'aspideus PNW15' © Jordan Gates, unsequenced Lactarius representaneus © Ian Gibson

Other Lactarius - click to expand
Species mentioned: Lactarius glyciosmus, pseudomucidus, controversus, pseudodeceptivus, argillaceifolius var. megacarpus, kauffmanii, kauffmanii var. sitchensis, mucidus, caespitosus, glutigriseus, affinis, trivialis, flexuosus, pseudoflexuosus, circellatus var. borealis, rufus, hysginus, hysginus var. americanus, necator, turpis, olivaceoumbrinus, sordidus, pubescens var. betulae, scoticus, torminosus var. nordmanensis, subvillosus, pseudodelicatus, sanmiguelensis, olympianus, zonarioides, vietus

Small species - click to expand
A few small species (~5 cm caps with stems <1 cm thick) somewhat resemble the Russularia. The rest of the species are stockier, with caps up to 10 cm or so and stems often >1 cm thick.
Species mentioned: Lactarius glyciosmus, pseudomucidus, glutigriseus.

Lactarius glyciosmus PNW04/PNW05 - Small, grey to lilac-grey, European birch species that smells strongly of coconut! There are 2 sets of sequences, 6bp apart in ITS, both found on both continents. PNW04 is found in Sweden (the type area) and interior BC so far. PNW05 is found in Italy, Alaska, northern BC and WA. It needs to be determined if there is one species or 2, and which is the real one and which needs a new name. From one photo of each, PNW04 is more atypically delicate and PNW05 has the slightly stockier habit that is more common.

Lactarius 'glyciosmus PNW04' © Connor Dooley,     L. 'glyciosmus PNW05' © Danny Miller

Lactarius glutigriseus AK (=L. pseudomucidus OR) - L. pseudomucidus is a small, dark brownish-grey capped and stemmed conifer mushroom described from Oregon with beautifully contrasting white gills, making for a lovely colour combination. It is extremely slippery all over. Its relatives, for instance L. kauffmanii below, are stockier and might be recognized by having a slight stem stickiness. Lactarius glutigriseus was described from Alaska under hemlock with the middle of the stem coloured but the top and bottom pale, however its type sequence matches the type sequence of L. pseudomucidus very well. It is the older name, so unfortunately, we should probably be using the little known older name instead of the popular name.

unsequenced Lactarius glutigriseus © Kit Scates Barnhart

Large, pale species - click to expand
The caps can get >15 cm and the colours are pale (white, or light greyish purple).
Species mentioned: Lactarius controversus, pseudodeceptivus, argillaceifolius var. megacarpus

Lactarius controversus EU - This is a large (~15 cm) white Lactarius with pink gills, although our sequenced collection shows it might not have those distinctive features. It can resemble Russula brevipes and Hygrophorus saxatilis unless you notice the latex. It is found with cottonwood, aspen and willow. Worldwide DNA seems to vary 1%, but ambiguous locations in some sequences mean that I can find at most 3 bp of real differences between them. We have BC and WA sequences.

Lactarius pseudodeceptivus WA - A similar conifer large, whitish Lactarius with perhaps a slightly bearded margin, no stem scrobiculation and without the pink gills. It could be confused with L. alnicola but that species has a somewhat scrobiculate stem and latex that may slowly stain the gills yellow, while this species may stain them brown. We have the type sequence from Washington, but no colour photos of confirmed collections, so we need more collections to understand how to recognize it.

Lactarius controversus © Ben Woo (unsequenced) and T. Abe Lloyd (sequenced),     unsequenced possible Lactarius pseudodeceptivus © Michael Beug

Lactarius argillaceifolius MI var megacarpus CA - Another large Lactarius, this one very large (may be 20 cm or more). It is only found in southern OR and CA under oak. It has a purple-grey cap and the gills stain brown (no beard, no scrobiculation). DNA shows it is distinct from east coast type variety sequences by 3-4%, so it does indeed deserve its own variety name. The type variety sequences also vary from each other by about as much, so there may be more varieties back east to be named.

Lactarius argillaceifolius var megacarpus © Danny Miller

Viscid stems - click to expand
These related species have stems that are usually somewhat viscid, although other species may too. The caps are usually greyish, orangish or purplish.
Species mentioned: Lactarius kauffmanii, kauffmanii var. sitchensis, mucidus, caespitosus, affinis, trivialis, flexuosus, pseudoflexuosus, circellatus var. borealis

Lactarius kauffmanii ID - This is our most common member, a dark brownish-grey capped conifer species with an off-white viscid stem, larger than L. pseudomucidus, and unlike that species, with a stem paler than the cap, described from Idaho, and found in BC, WA and OR too.

This type sequence and the type sequence of the supposedly rare L. kauffmanii var sitchensis OR from Oregon are identical and match all of the other sequences we have, so I don't think var. sitchensis represents a true genetic variety. It was described as growing under spruce with creamy yellow spores instead of white spores, but they did note quite a lot of variety in this species, with forms with white, cream or yellow spores and milk that slowly stained olive, brown, olive-brown or not at all, so it's not surprising that the one specimen they did call out as a different variety did not turn out to be genetically different.

Lactarius caespitosus WY - a Rocky Mountain species also in the L. kauffmanii group, with a somewhat paler grey-brown cap than L. kauffmanii, and a viscid stem that is more pure white. It has larger spores too and a buff spore print. Cathy Cripps has provided ITS DNA from Montana, and matching collections have been found in WA and OR.

Lactarius mucidus NC - similar to L. kauffmanii, but smaller, perhaps with a pale cap margin, the milk staining the gills yellow or green. Two east coast varieties have been reported from the PNW and need confirmation by DNA. It is expected that all of these species will be genetically closely related.

Lactarius kauffmanii © Steve Trudell,     L. caespitosus (from MT) © Edward Barge

Lactarius PNW07 - This WA collection sequenced to be related to this group, but there's no other DNA yet that comes close enough to know what it is. The most logical conclusion is that it's something reported from the PNW that hasn't been sequenced yet, mentioned elsewhere on this page but I haven't connected the dots yet. It was found near spruce.

Lactarius PNW07 © Bee Marcotte

Lactarius trivialis EU - caps tinged violet-brown when young, but mature caps turning cinnamon-orange with a matching stem. Supposedly slowly, slightly peppery in taste. DNA exactly matching that of many EU collections was found in northern BC and the species has been reported from ID and WA, where it was finally sequenced and photographed. Conifers.

Lactarius affinis NY - closely related to and much like L. trivialis, but usually with a viscid cinnamon-orange cap and stem in all stages (although one was mostly brown). Also peppery tasting. No zoning (note that the more common L. olympianus below may sometimes lack zoning, but it has a dry, white stem). Some sequences labeled as this species are actually L. trivialis, but if the sequences that are not that species are correctly labeled as this species, including one from Quebec, then we know what this DNA looks like, and DNA from Vancouver Island and interior BC matches that within 3 bp, so it's reasonable to assume we have the real species here.

Lactarius trivialis © Sharon Squazzo,     Lactarius affinis © James Holkko and Ed Barge

Lactarius flexuosus EU (=L. circellatus var. borealis ID) - greyish brown cap with lilac tones, zoned especially near the margin, and with a tinge of colour in the gills. The stem may not be viscid. With birch and cottonwood. Closely spaced gills. Like L. olympianus, it has been found without cap zoning, making it resemble some of the grey species above.

Hesler and Smith were unable to figure out what L. flexuosus was back in 1979 since it was only known by the vague 1821 description that the cap colour was "incarnato-vitellino", and it seems they re-described that mushroom as a variety of L. circellatus, L. circellatus var. borealis. Since then the Europeans appear to have figured out what L. flexuosus is, and there are dozens of EU sequences that all agree. The holotype sequence of L. circellatus var. borealis and all of our modern PNW collections so far match sequences of L. flexuosus very well, differing at most by 1 bp and 1 indel. Lactarius pseudoflexuosus, from back east, appears to be a sister species with similar DNA (an additional 3 bp differences). L. flexuosus is not genetically close enough to L. circellatus to be considered a variety of it anyway.

Lactarius flexuosus © Andrew Parker, with atypical azonate cap © Danny Miller

There are isolated, unconfirmed sequences of local DNA of unknown or undescribed species, so we probably don't know the whole picture yet.

Other Lactarius - click to expand
Species that do not fit the other descriptions.
Species mentioned: Lactarius rufus, hysginus, necator, turpis, olivaceoumbrinus, sordidus, pubescens var. betulae, scoticus, torminosus var. nordmanensis, subvillosus, pseudodelicatus, sanmiguelensis, olympianus, zonarioides, alnicola, payettensis, vietus

Lactarius rufus EU - This European conifer species is a member of Russularia but can get so large you might not look for it in that group of usually small mushrooms. It is a brick reddish colour, but most importantly is exceedingly hot tasting and might be identified on that basis alone, if you're brave enough to try it.

unsequenced Lactarius rufus © Steve Trudell

Lactarius hysginus var. americanus CA - robust, reddish-brown usually zoned cap, usually scrobiculate stem. We have a CA sequence that probably represents this and a matching sequence from ID.

Lactarius hysginus var hysginus EU - has also been reported from here, but so far we haven't found local DNA to match our EU DNA. Be on the lookout for this. It differs by 1.5% in ITS.

Lactarius hysginus var. americanus © Joe Matanzas (ID) and Alan Rockefeller (CA)

Lactarius 'necator PNW09' - My favourite beautifully ugly toadstool, dingy dark greenish with orange or other colours mixed in. The colouration is unmistakable. It is a relatively common European mushroom that grows with birch. There are three competing concepts for this EU species in the EU, and this matches one that some people think may be the real thing, but it also might not be. This species has also gone by the name Lactarius turpis.

Lactarius olivaceoumbrinus WA - almost identical looking (perhaps darker and more slender) local west coast conifer species described from Mt. Rainier, WA. We have the type sequence and a Vancouver BC matching sequence. As well as being found with different trees, its milk may slowly stain green! It may also be common, but since they're so hard to tell apart, I don't know which is more common.

Lactarius sordidus NY - a third similar, conifer species, also not necessarily closely related, from the east coast rumoured from Idaho, but we have no DNA confirmation yet of what this species actually is. It is more yellow-green.

unsequenced Lactarius necator and olivaceoumbrinus © Steve Trudell,     unsequenced L. sordidus © R. Lebeuf

Lactarius pubescens EU var betulae MI - found under birch, in dry places, with a pale cap with hints of pinkish-orange and a bearded margin (but not with a scrobiculate stem). This eastern North American variety is said to differ from the European L. pubescens by milk that might slowly stain yellow. There's not much rhyme or reason to worldwide sequences purporting to be some variety of L. pubescens or the similar L. scoticus (described next). It's all a mess of sequences about 1% different from each other. We might need more genes to tell them apart and figure out how many varieties/species there are. The few known NA sequences I have cluster somewhat together and match the type sequence of var. betulae, so I am going to refer to our variety by its local NA name, even though the EU type variety is also reported from here and may or may not be distinct.

Lactarius scoticus PNW06 - a somewhat smaller L. pubescens from wet bogs. Our one OR sequenced collection was small and from a bog, and did sequence a bit apart from our local collections of L. pubescens var. betulae, but it had the large spore size of L. pubescens, not L. scoticus. And also considering that sequences from the EU cannot reliably differentiate between L. scoticus and L. pubescens, I am not going to assume that ours is the actual species.

Lactarius torminosus EU (=var nordmanensis ID?) - has a bit more pigment (darker pinkish-orange) and some zonation on the cap. But otherwise it is a similar bearded species found under birch and sometimes other hardwoods. We have the ID type sequence of var. nordmanensis, and matching DNA from Victoria and the BC interior. L. torminosus var nordmanensis is said to differ from the European type variety by milk that might slowly stain yellow, but our sequences match most EU sequences very well in ITS so I am not sure if we need to consider ours a distinct variety. Both varieties are reported from the PNW.

unsequenced Lactarius pubescens var. betulae © Danny Miller,     L. 'scoticus PNW06' © Connor Dooley (2 images),     Lactarius torminosus © Ed Barge

Lactarius pseudodelicatus MI - A closely related yellow- to orange-buff zoned cap that is also bearded, with a scrobiculate stem. Found in the Rockies under cottonwood and aspen with a fruity, citrusy odor and acrid taste. The milk is said to be unchanging. We have sequenced collections from ID. Note that L. payettensis, below, is very similar, but more yellow than orange.

Lactarius crassus CA - is a closely related trufflized Lactarius. It is interesting to note the anastamosing gills in the middle picture below in the context of realizing that it has a closely related trufflized sister species.

Lactarius subvillosus CA - Very similar to L. pseudodelicatus, and closely related, but with a brighter orange, zoned cap that is bearded, with a scrobiculate stem. Mild odor, acrid taste. It is a southern species described from CA and also found in southern OR. DNA from Oregon is a couple bp and a couple indels different from the CA type sequence near the beginning of the sequence. ITS DNA of a sister species was found in Oregon, so we need to investigate if this is a species complex.

Lactarius pseudodelicatus © Cathy Cripps, Joe Matanzas (2 images),     Lactarius subvillosus © Christian Schwarz

Lactarius zonarioides EU (=Lactarius olympianus WA) - This conifer, orange, zonate capped species is not bearded and has a dry white stem. Note that sometimes it is not at all zoned, in which case it will resemble Lactarius affinis above, but that species has a viscid cinnamon-orange stem. Our local species, L. olympianus, described in 1979 from the Washington Olympic coast, has a holotype sequence identical in ITS to the 1953 European species L. zonarioides, so that older name should take precedence. When describing L. olympianus, Hesler & Smith realized that it was possibly the same mushroom as L. zonarioides, but back in 1979 there was some confusion as to what mushroom L. zonarioides referred to, so to be on the safe side, they gave it a new name anyway. It appears that the confusion has now been resolved.

Lactarius olympianus © Andrew Parker (zoned) and Leah Bedlin (unzoned)

Lactarius vietus EU - This is a northern, grey, European birch species with milk that turns grey and stains the gills grey. Formerly only reported in the west from CO and ID, but the DNA keeps turning up in BC. We need a photo of a verified specimen.

probable Lactarius vietus © Buck McAdoo

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.

Summary of Future Studies Needed - click to expand