Indigo Milky Caps – An Admirable Edible NC Mushroom

Editor’s Note:

Every time I sit down to write an article about one of the many delicious species NC edible mushrooms, I am tempted to start my notes with an exclamation about how it’s one of my favorite fungi of all time. This is perhaps due to the excessive excitement and delight I derive from wild mushroom hunting, and my esteem for many different species edible mushroom that grow in North Carolina’s Research Triangle.

All superlatives aside, the indigo milky cap, Lactarius indigo, is a terrific NC edible mushroom, and it is an excellent candidate for novices who are new to mushroom hunting in the southeastern United States. It is not so much the flavor of the indigo milky cap (which is quite nice and mild) or its texture (which tends toward the crunchy and pleasantly brittle) so much as its sheer pizazz! There are some other blue-purple edible mushrooms in this world that I also enjoy, such as the blewitt (Clitocybe nuda) and the amethyst laccaria (Laccaria amethystina), but they simply do not hold a candle to the indigo milky cap when it comes to vibrant coloration, interesting physical features, and downright coolness! Also, these mushrooms grow throughout the summer chanterelle season in North Carolina, and can be found well into the autumn months as well, when mushroom hunters turn their attentions towards maitake (hen of the woods, Grifola frondosa), lion’s mane and bear’s head (Hericium erinaceus and Hericium americanum, respectively), and other fall-fruiting North Carolina edible mushrooms.

Lactarius indigo
The indigo milky cap, Lactarius indigo. These are specimens from Jalisco, Mexico. Note the concentric zones on the cap. Photo by Alan Rockefeller. Licensed under Creative Commons Attribution-ShareAlike 3.0 Unported. Alan Rockefeller is rad and takes rad mushroom pictures.

Since it is easy to find and grows for a significant period of time, the indigo milky cap is an excellent NC edible mushroom for foragers. So, dear reader, take a peek at what follows for a snapshot of the indigo milky cap mushroom, including lookalike information, seasonality, habitats, and edibility notes!

Yours in Fungal Fancy,

Mushroom Anna

Overview of the Indigo Milky Cap – Lactarius Indigo

The indigo milky cap, Lactarius indigo, is a widespread and semi-common mushroom in North Carolina. In fact, its distribution in North America is tremendous, including in the great golden Southwest, the Northeastern U.S., Mexico, and Texas. In fact, some experts opine that with further genetic study, the indigo milky cap may need to be divided into several different species. Its extensive distribution and diverse mycorhizzal partnerships hints at the possibility that this mushroom may in fact represent more than one specific species. As with everything in mycological study, where so-called splitters conduct genetic and molecular analysis of fungi and discover that mushrooms that look alike are often different species, only time will tell, but my bet is riding on Lactarius indigo becoming more than one species in the future.

Sadly, the indigo milky cap does not occur in the Pacific Northwest, California, or some of the mushroom-rich regions of the Rocky Mountains. Lactarius indigo is quite easy to recognize, which makes it a terrific mushroom for those who are getting their feet wet in mycology, and haven’t gone full-blown mushroom nerd…yet (if you’re not sure whether or not you’re a “full-blown mushroom nerd,” check your symptoms here).

Indigo Milky Cap – Key Features

Lactarius indigo is a handsome mushroom that is smurf-blue throughout most of its development. The indigo milky cap is a classic cap-and-stem mushroom that starts out with an inrolled cap margin that eventually unfurls, making the mushroom sometimes look vaguely vase-shaped (exposing the gills) when it reaches full maturity. The indigo milky cap can get quite large, and its cap is typically between 4 and 7 inches in diameter. As indigo milky caps age, they typically develop patches or pits of greenish discoloration on the cap, which is an extremely common feature that it shares with many other species in the Lactarius genus.

The most distinctive feature of the indigo milky cap, however, is its latex, which is milk that oozes from the gills when the

Lactarius indigo milk
Has this person been collecting Lactarius indigo or getting a little too rough with the Smurfs? Photo by Dani (Mia Celia). Licensed under Creative Commons Attribution-ShareAlike 3.0 Unported.

mushroom is damaged. The latex of the indigo milky cap is bright blue, and some specimens dump a huge load of the stuff when the gills are cut. Furthermore, when slicing the indigo milky cap from end to end, you may notice intense blue staining on the outer edges of the flesh. Some indigo milky caps produce so much latex that your knife may look like it was used for smurf-slaying instead of mushroom harvesting! After some time exposed to air, the blue juice that the indigo milky cap bleeds will turn dark forest green. The spores of the indigo milky cap are cream-colored.

Lactarius indigo is mycorrhizal, meaning that it grows in association with a plant or tree partner. In the case of North Carolina indigo milky caps, they are most frequently found growing in association with pine, oak, and hickory. Considering that these three types of trees are among the most common in North Carolina, you can find Lactarius indigo practically anywhere. I frequently find them in wooded parks under mature pin oak and in pine forests near a creek or another source of water. Usually this species is not terribly gregarious, and each mycelium (in my experience) only produces a few fruiting bodies at a time, so I usually end up with a small handful of them each time I harvest them in NC’s forests.

The flesh of indigo milky caps is brittle and easily broken, so take care when handling them, lest they get banged up and broken to bits. I usually separate them from the other mushrooms I am hunting as well so that I do not stain my chanterelles and other colorful mushrooms with the blue juice. The intense blue latex of the indigo milky cap seeps into dishes that include it, although much less so if they’re allowed to cool their heels in the fridge for a day or two after collection. Tom Volk recommends mixing them with scrambled eggs to make green eggs and ham, and although I’ve never tried this particular trick, it remains on my myco-geek bucket list and I’m sure to strike it off said list in the coming months!

Indigo Milky Cap Lookalikes

Lactarius indigo is edible and choice, and especially the younger specimens are crunchy and mild-flavored and do well in sorts of dishes or just sauteed on their own. They have a few lookalikes that occur in North Carolina, including Lactarius cheledonium, Lactarius subpupureus, and Lactarius paradoxus, but these species are distinct in their own ways and misidentification of the indigo milky cap is, from my point of view, quite unlikely. As with all things related to mushroom identification, however, keep in mind that you want to look at all the mushroom’s features, and make sure that these traits line up entirely with the mushroom you’ve found. And of course, if you find what you think is an indigo milky cap but you’re not sure, snap a couple good mushroom photographs and get in touch with a mycological expert to verify your identification! Here is a quick rundown of the other Lactarius mushrooms that share enough features with Lactarius indigo to warrant being mentioned.

Lactarius chelidonium var. chelidonioides

Lactarius chelidonium var. chelidonioides is a mushroom that I have found quite frequently in the fall in North Carolina, and it does bear some resemblance to the indigo milky cap some of the time. When it is young, this mushroom tends to be a little purplish-blue, but as it ages its cap tends to turn dingy orange, and even when young, the blue caps of these mushrooms can have patches of brownish coloration. Furthermore, Lactarius chelidonium var. chelidonioides has gills that have tinges of yellow and are relatively light in color, as opposed to the dark blue-purple of the indigo milky cap. In addition, the latex of L. chelidonium var. chelidonioides tends to be yellowish to yellow-brown. As the mushroom ages, it turns lurid green, either in whole or in part, like many other mushrooms in the genus Lactarius. Given the color differences between the indigo milky cap and Lactarius chelidonium var. chelidonioides, I consider confusion of the two to be unlikely, but it’s always helpful to keep in mind that when seeking out the indigo milky cap, you should look for mushrooms that are blue-purple on both cap and gills, with blue latex! Lactarius chelidonium var. chelidonioides is listed as inedible/edibility unknown by Rogers Mushrooms, and evidently it has a faint peppery taste. One additional note on this mushroom: I have always found it growing later in the year than the indigo milky cap; whereas the former is really a summer and early fall mushroom in and around Raleigh, I usually find Lactarius chelidonium var. chelidonioides in the fall in the North Carolina Piedmont, between October and November.

Lactarius paradoxus

Lactarius paradoxus
The silver-blue cap of Lactarius paradoxus. Photo by Jason Hollinger. Licensed under Creative Commons Attribution-ShareAlike 2.0 Generic.

This mushroom is another one I find fairly frequently in the North Carolina Piedmont, and as the name implies, it is a little unusual. When it is young, it can easily be identified by its blue cap and pink-purple-reddish gills. The surface of the cap often also has a sort of silvery coloration in addition to the blue, and on the whole it usually does not appear to be as vibrantly colorful as the indigo milky cap. Its gills exude a small amount of reddish-purple latex when they are damaged, but compared to the vibrant dark blue milk of Lactarius indigo, this mushroom’s latex is scant. Over time, it begins to discolor and becomes greenish, tan, or buff. This is another mushroom that I frequently find a little later in the year than I typically see Lactarius indigo in the North Carolina Piedmont, for what it’s worth. The main difference is in the gill color (which in paradoxus is pink-purple) the cap color (which is blue with shades of silver, but not strikingly blue like the indigo milky cap), and the latex, which is lighter in color and less voluminous than is typical of Lactarius indigo.

Lactarius subpurpureus

To call Lactarius subpurpureus a lookalike to the indigo milky cap is a bit of a stretch, because even though this mushroom is a reddish-purple or pink color, it lack blue tones on its cap, gills, and latex. The milk of Lactarius subpurpureus is a dark, wine-like red, and the gills tend to stain green over time. As the mushroom ages, its cap also often turns a dingy green color. This mushroom is widespread in the eastern United States and the midwest, and grows under hemlock. One other feature that helps distinguish it, besides its latex being reddish in color, is the fact that it often fades to dull pink or buff over the first few days of its growth cycle. Some people report that this mushroom is edible, but it possesses a peppery flavor and may disagree with some people. This is not a mushroom I plan to add to my “to eat” list, although it is quite pretty to look at.

Lactarius subpurpureus
A photo showing the pink-red cap and wine-red latex of Lactarius subpurpureus. Photo by Dan Molter. Licensed under Creative Commons Attribution-ShareAlike 3.0 Unported.

Clitocybe nuda, the Blewitt

As mentioned in the introduction to this post, the indigo milky cap is not the only edible blue-purple mushroom in North Carolina. The blewitt, Clitocybe nuda, is another such mushroom, but it is easily distinguished from Lactarius indigo because it does not exude juice when its gills are cut. In addition, the flesh of blewitts is much less brittle, and the cap lacks the distinctive concentric zones that are so extremely common in the genus Lactarius. Finally, the blewitt is usually a bit purple and a bit brown, and in some instances it looks almost entirely fawn brown with slightly purple-colored gills. Anyway, the blewitt is edible and choice, but it’s certainly not the same as our subject today, the indigo milky cap.

Purple Cortinarius mushrooms

There are some mushrooms in the suspect genus Cortinarius that are purple (including a species that’s found in the eastern United States called Cortinarius iodes), and you should generally avoid them, because at least a couple Cortinarius mushrooms are deadly poisonous! However, it’s easy enough to distinguish a Cortinarius from a Lactarius, being that the Cortinarius mushrooms have a cobwebby ring on their stem, which is the remains of a frail partial veil that covers the gills as the mushroom emerges. Furthermore, mushrooms in the Cortinarius genus normally have rust-colored spores, so as they mature, their gills tend to take on a rusty hue. Finally, the gills in Cortinarius do not exude latex!

Purple Laccaria mushrooms

The amethyst laccaria, Laccaria amethystina, is another purple mushroom that you might be inclined to think is the indigo

Laccaria amethsytina
Laccaria amethystina. Photo by Holger Krisp. Licensed under Creative Commons Attribution-ShareAlike 3.0 Unported.

milky cap upon first glance. However, they’re quite different in a number of features, including stem length (Laccaria mushrooms tend to have a longer, solid stem, whereas Lactarius mushrooms have a stout, shorter stem that is often hollow, or at the very least brittle and easily broken apart) and gill structure (Laccaria mushrooms have thick, widely spaced gills that look quite deep, compared to Lactarius’ close-spaced gills). Moreover, Laccaria mushrooms do not have latex! Finally, the amethyst laccaria, and several other mushrooms in this genus as well, have streaky patterns on the stem that are quite pretty and distinctive.

Indigo Milky Cap – Edibility Notes

The indigo milky cap is pretty tasty, although like all wild mushrooms, it should be cooked thoroughly. Given its brittle nature, it’s best to slice it carefully so that it doesn’t break apart on you! Another thing to note: although some mushrooms do well when you try to remove their gills, don’t bother with the indigo milky cap; the second you start trying to pull the gills loose, the whole mushroom is likely to break apart in your hands. Furthermore, the gills of this mushroom are pleasantly firm and are not at odds with the remainder of the cap, as with some other mushrooms (particularly boletes, which can have a sticky or slimy sponge that is best removed before cooking).

The indigo milky cap is excellent from a culinary perspective not just because of its nice flavor…it’s also so vibrantly colored that it makes a wonderful addition to dishes that could use a little flash and panache! I really like to slice it thin and then gently fry in in olive oil with a little garlic powder, salt, and pepper for a few minutes on each side, just enough to brown it a little bit and get the edges crispy. Then I add it on top of rice-based dishes or other grain and veggie combinations that are hearty and tasty, but lacking in curb appeal.

…Or you could always make green eggs and ham!



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