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Indigo Milky Caps: Identification, Foraging, and Cooking

Modified: Nov 14, 2022 by Jenny · This post may contain affiliate links · Leave a Comment

These stunningly bright blue mushrooms aren’t just a beautiful woodland find but also a superb edible species. Indigo Milky caps (Lactarius indigo) are widespread across eastern and southern North America and especially prevalent in the Appalachian Mountains. The indigo milkcap mushroom is easy to identify, making it a great beginner mushroom…if you are lucky enough to find it!

stunning blue milky cap mushroom
The gorgeously blue Lactarius indigo, the indigo milky cap mushroom
Lactarius indigo by Cathy Pfeiffer on Mushroom Observer

Fun Fact:

Want to impress the kids? This mushroom is an easy, natural way to make Dr. Seuss’ Green Eggs and Ham. Add indigo milky cap mushrooms to scrambled eggs, and they’ll turn an excellent green color.

View post on imgur.com
Green Eggs and Ham with Indigo Milk Caps By Letchworth On Reddit
**click on the video for the 3 horizontal dots that will allow you to change settings and SLOW DOWN the playback speed
Jump to:
  • All About Indigo Milky Caps
  • Indigo Milky Cap Identification
  • Indigo Milky Caps Lookalikes
  • Cooking With Blue Milky Caps
  • Indigo Milky Cap Common Questions

All About Indigo Milky Caps

The indigo milky cap mushroom is also commonly called the blue lactarius, indigo lactarius, blue milk mushroom, and indigo milk cap. It is part of a family of milk caps that also includes the saffron milky cap.

Indigo milk cap mushroom caps range from bright blue to a somewhat subdued blueish-gray cap, and this colorful cap hides a beautiful surprise underneath. The gills are brilliant blue, and when you cut them, they bleed a deep blue milky latex substance.

indigo milky caps
Lactarius indigo by Icyurmt on Mushroom Observer, bleeding blue

This blue mushroom is somewhat rare in appearance, and many thought it to be the only one with this particular deep blue-violet milky latex. However, just recently, in 2007, five new to science species were reported from Malaysia.

Blue milk mushrooms are sought after by foragers due to their choice edibility. However, not everyone agrees on their desirability. Some mushroom hunters report it as mediocre, citing a bitter or peppery taste and grainy texture. It may be that specimens in different regions have various bitterness or peppery qualities. The range and habitat for this species are rather diverse, so it makes sense its taste might be as well.

lactarius indigo
Blue milky cap mushroom by dianelily on Mushroom Observer

It wouldn’t be surprising to learn, after some intensive DNA analysis, that there is actually more than one species. A smaller variant of the blue milky cap is already differentiated (unsure if it is scientifically DNA separated). It is known as Lactarius indigo var. diminutivus, the smaller indigo milk cap. The caps on this type don’t get larger than 3 inches in diameter with a stem averaging .5-1.5 inches long.

It is not unheard of for a Lactarius species to be bitter or spicy. Many milky caps are inedible due to their bitter taste. And, the peppery milkcap is appropriately named – it will burn your tongue.

The great thing about indigo milky caps is their long fruiting season. In many areas, they will appear starting in late spring and continue through late fall.

This mushroom is used to dye cloths. To learn more about dying with indigo milkies, check out this article. If you’re interested in learning about using mushrooms as a natural dye, International Mushroom Dye Institute is a phenomenal resource. Indigo milkies are even being used as a dye for cellular biologists.

In Honduras and Mexico, this mushroom is collected and sold in markets.

blue lactarius
Indigo milky caps by Sandra on Mushroom Observer

Indigo Milky Cap Identification

Season

June through October, depending on region and climate.

Habitat

The indigo milk cap grows in the eastern, southeastern, and southwestern United States. It can be found in Texas and Arizona but does not grow on the West Coast or Pacific Northwest. They’re also found in East Asia, Central America, and France.

Blue milkcaps are mycorrhizal, forming mutualistic relationships with their preferred tree species. Because of this, they’ll always be found around trees. They seem to prefer recently flooded floodplains. They grow from the ground, never on trees or from dead wood.

Indigo milkies grow in mixed habitats, sometimes preferring oaks and, other times, pines. There is some speculation that they’re more common around pines, but they definitely grow with oaks and other hardwoods, too. Other trees they’re known to associate with include American hornbeam, Mexican alder, and Mexican pine.

Usually, where one is growing, others will be scattered nearby. Blue milkes tend to grow in sporadic to dense dispersed groupings.

blue milky cap mushroom
Blue milkies are mycorrhizal, developing interconnected relationships with trees.
Lactarius indigo by Jon Shaffer on Mushroom Observer

Identification

Cap

The cap of the indigo milkcap is medium to deep blue – think smurf blue! When the cap is at its brightest point (usually when young and fresh), you may think you’ve run into a smurf home. It starts out flat or slightly convex with an inrolled margin (margin folded under). The rolled margin is a common characteristic of milky caps in general.

As the caps age, they take on a grayish hue, turning the bright blue into a muted gray-blue or silver-blue appearance. The shape of the cap also transforms with age, lifting upwards to create a vase shape. It is also not unusual to see brown, stain-like markings on top of the cap.

The blue cap coloring usually appears in concentric zones, although there isn’t always a difference between the colors in the zones. More often than not, though, the circular markings are very distinctive, with darker blue lines across a paler gray-blue background.

The cap ranges in size from 2-6 inches in diameter. It also stains green when handled or bruised.

array of blue milkycap mushrooms
The cap coloring on the Blue milky cap mushroom varies widely. Notice the concentric color zones, too. The gills are usually much much brighter than the caps! Lactarius indigo by Luke Smithson on Mushroom Observer

Stem

Indigo milk cap mushroom stems are .75-3 inches long, equally thick, and grayish blue in color. They are hard, hollow, and brittle. If you break it, it will snap or fall apart. The stems usually have pockmarks down the length.

Blue milky cap mushroom
Indigo milky cap stems often are pockmarked. Lactarius indigo by Ron Pastorino on Mushroom Observer

Gills

The gills of the indigo milky cap are bright blue to grayish blue. When sliced, the gills bleed a deep indigo blue that slowly stains green(ish). The green happens when the latex is exposed to air. This is a telltale sign you’ve found a blue milky cap.

Milky cap latex does dry up with age, though, so on older specimens, there may not be any milk exuded or very little. Evidence that it did bleed at one time is generally apparent, even if there isn’t any milk. The gills will be stained darker blue or blueish-green to greenish-yellow.

Flesh

Indigo milky cap flesh is white but turns indigo blue rather quickly. The blue will then turn slowly greenish.

blue gills of indigo milky cap
Bright smurf blue gills! Lactarius indigo by Cathy Pfeiffer on Mushroom Observer

Spore Print

Cream

On The Lookout

Milky caps like lots of rain and good rich soil. Bugs love them so it’s often quite challenging to find milky caps that are even worth foraging. Slug-ridden, bug-infested indigo caps are a common disappointing find.

Try looking for this edible mushroom a day or two after good, heavy rains. All milkcaps (and there are many species!) tend to like similar habitats, so if you see another milkcap species growing, know it could be a place to look for the indigo milkies, too.

lactarius indigo mushroom
Getting to these mushrooms before the bugs and slugs is always a challange. Lacatrius indigo by RuthsWorld on Mushroom Observer

Indigo Milky Caps Lookalikes

There are several blue mushrooms in the fungi world, but this one has some key telltale points which set it apart from others.

Wood Blewits (Clitocybe nuda)

Blewits, as the common name suggests, are blue. But, they tend to be more lavender, deep purple, or light blueish than the brighter blue of indigo milky caps. In overall appearance, they aren’t that different from Lactarius indigo. The big difference is blewits are not milky caps, and therefore do not bleed any latex. So, cut the gills to be sure.

Blewits are an excellent edible, so if you do find this one, keep it and mark the spot. Most people would be very thrilled to find blewits instead of indigo milky caps. The spore print is whitish to pinky-beige.

Wood Blewits are more purple/lavender than blue. Also their gills don’t bleed when cut. Clitocybe nuda by Huafang on Mushroom Observer

Purple Corts (Cortinarius sp.)

There are several Cortinarius species with deep purple caps that may get confused with the indigo milk cap. When young and fresh, these Cortinarius species’ color is vivid and definitely purple, not blue. However, as the fungi age, their colors fade and might cause confusion. Corts are not edible, and some are actually quite toxic.

There are several key tells between corts and indigo milky caps. Cortinarius species always have a bulbous stem base, while indigo milkies are straight. Additionally, their gills don’t bleed. Finally, corts start out with veils around their gills which then break apart with age, leaving behind white webbing-like material around the cap edge and gills.

Cortinarius alboviolaceus by Robert Eberhardt on Mushroom Observer. There are several Corts that resemble the indigo milkycap at first glance. They’re easily differentiated, though.

Lactarius chelidonium var. chelidonioides

This milky cap starts out a pale blue that is reminiscent of the indigo milky cap. It also shares the blue staining inner flesh. However, it is quickly apparent this is not an indigo milky. The cap coloring changes from blueish to brownish-yellow to dull orange – very different from the blue milky cap. The gills on this species are yellowish to dull orange, also significantly different from the indigo milky.

This is an edible mushroom, but possibly not choice – taste descriptions vary from mild and pleasant to slightly peppery.

This lactarius might look like a pale blue milky cap, Lactarius chelidonium var. chelidonioides by Huafang on Mushroom Observer

Lactarius paradoxus

It is easy to differentiate this species from the blue milky cap by cutting the gills. While the caps are a similar blue or bluish color, the gills on L. paradoxus bleed red, not blue. This is an edible species with a mild taste.

Lactarius paradoxus by Chris Cassidy on Mushroom Observer. This species bleeds red, not blue.

Cooking With Blue Milky Caps

The flavor of indigo milky caps is mild to bland to slightly spicy. People who have eaten this mushroom report a wide range in tastes, from mild (and possibly “boring”) to peppery and not enjoyable.

It is a good idea to taste test a tiny bit before adding this mushroom to any dish. You don’t want a peppery surprise. Or, be expecting peppery and get bland. A nibble and spit test is fine to do.

Indigo milky cap mushrooms WILL stain your food green. So, either prepare them in a dish where it won’t show, or be prepared for some interesting colored food. When you saute the mushrooms, they’ll lose their brilliant blue coloring.

blue milk mushroom
These are a fun mushroom to cook with! Lactarius indigo by Sarah Culliton on Mushroom Observer

It is possible to keep a lot of the signature coloring by blanching them first, but this prevents some of the fine flavors that come from sauteeing in oil or butter.

In Honduras, the indigo milky cap is known as chora and is prepared with eggs. You can use the indigo milkies in any recipe that uses saffron milk caps.

Indigo Milkcap Recipes

  • Indigo Milkcaps preserved in Herb Oil
  • Breaded and Fried Indigo Milk Caps
  • Lactarius Indigo Vinaigrette
  • Sauteed Milkcaps
indigo lactarius mushroom
Keep a look out for blue(ish?) concentric zoned caps growing in the ground and you might find yourself lucky! Lactarius indigo by Jeff on Mushroom Observer

Indigo Milky Cap Common Questions

Wait, aren’t all blue mushrooms hallucinogenic?

For those seeking an otherworldy experience, I’m sorry to inform you that the indigo milky will not take you there. That is, unless finding a culinary mushroom is exhilarating enough to blow your mind.

Blue does not equal hallucinogenic properties; many mushrooms actually stain blue and aren’t magic.

Are Indigo Milk Caps Rare?

They’re not rare, but do tend to be an uncommon find. They have a widespread growing range, but finding them each season can be challenging. And then, when you do find them, it’s a whole truckload (slight exaggeration…). So, if you do find this beautiful gem, treasure it!

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Jenny foraging for mushrooms

Hi, I'm Jenny! I am a seasoned mushroom expert with over 10 years of experience in the field of mycology. My blog focuses on North American mushroom species.

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