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The Amateur Mycologist #6 - Lactarius indigo - The Indigo Milk Cap

The Amateur Mycologist #6 - Lactarius indigo - The Indigo Milk Cap

These posts are not for foraging. They are intended for entertainment and educational purposes only. These posts are not a field guide nor comprehensive in any way - their accuracy is not assured in any way. Do not eat wild mushrooms unless you are a professional or have a wealth of personal experience with a specific species. Do not make any foraging decisions based on these posts.

These Posts Contains No Information Regarding Edibility Or Toxicity


One of the most beautiful mushrooms on earth.

Lactarius Indigo - The Indigo Milk Cap. Stumble upon this beauty in the forest and you won't be able to resist its charms. You may need to look closely as detritus can sometimes adhere to the cap and keep the mushroom obscured from view. But once you see it, you'll know.

This fungal miracle grows in Eastern and Southern North America, but primarily down on the gulf coast in Mexico. Sometimes it will be found in the Appalachian Mountains, although I have yet to be so lucky.

NY is probably too far north. As a result, I've never seen one in person, so the photos in this post are all wikicommons with citations at the bottom.

The astonishing blue color of Lactarius indigo is only part of its allure.

The really amazing stuff happens when you damage the mushroom

The reason this mushroom is called the Indigo MILK mushroom is because when you damage the gills or cut the flesh it exudes a kind of milky, latex like substance. In this case, the "milk" is bright blue.

Indeed, that is the primary indentifier for inclusion in the Lactarius genus - every Lactarius species exudes some kind of milk or latex when cut or damaged, as long as they have received enough rain.

In the case of Lactarius indigo, the color of the mushroom and its amazing hue of its milk, almost seal the deal as far as identification is concerned. Having said that, there are some other Lactarius that could be mistaken, theoretically, for this mushroom, and so best practice is to go through all of the identification steps, as always!

Lactarius Indigo is mycorrhizal - which means, like Chanterelles and probably Morels - this blue mushroom's mycelium creates a mutually beneficial relationship with the roots of a nearby tree or trees. The mycelium and the tree will exchange goods, with the mycelium giving the tree minerals and proteins while taking carbon from the tree to build more mycelium and mushrooms.

This relationship means you can often find Indigo Blues on the ground in deciduous and coniferous forests. (Deciduous are the kinds of trees whose leaves fall off every year and Coniferous are mostly ever-greens and pines). Specifically look for these mushrooms nearby oak or pine trees.


Macroscopic Features:

  • Cap = 2.0 to 5.9 in wide (5 - 15cm) - convex becoming almost funnel shaped as it ages. As seen above, young specimens have the cap rolling inward at first - then it spreads out as it matures. Sticky when young.
  • Gills = Adnate to a bit decurrent
  • Flesh = Blue to light blue - turns green as exposed to air - black as exposed to heat. Brittle, like many Lactarius species.
  • Stem ("stipe") = .8 - 2.4 in tall by .4 - 1.0in thick (2-6cm by 1-2.5cm) - solid, not hollow. Sticky when young, then dry.
  • Spore Print = Cream colored - not blue.
  • Ecology ("What it grows on") = Mycorrhizal, found in forests - often near Oaks or Pines, on the ground.
  • Distribution = Eastern and Southern North American, including Appalachia - primarily Gulf Coast of Mexico.
  • Other Traits = Beautiful blue gills and usually blue flesh. Unless dried out, cutting the flesh or damaging the gills will cause the mushroom to exude a milky latex in a bright blue color. This latex turns dark green after awhile exposed to air.

Disclaimer 2

The only 100% way to avoid being hurt by a wild mushroom is not to eat a wild mushroom. These posts are not field guides - they are intended for the mycology enthusiast, not the forager. If you want to forage mushrooms there are professional resources available to that end online as well as local mycological societies all over the world which you should connect to for guidance.


For The Online Mycokey program look Here

For a Glossary Of Relevant Mycological Terms, Micheal Kuo's Website Provides


Photo Sources: [1]Dan Molter [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons [2]By This image was created by user Alan Rockefeller (Alan Rockefeller) at Mushroom Observer, a source for mycological images. You can contact this user here. [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons [3]By Alan Rockefeller (Mushroom Observer) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons [4]By Alan Rockefeller (Mushroom Observer) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons [5]By user: Eddee (ravenhawkdr) (Mushroom Observer) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Information Sources: https://en.wikipedia.org/wiki/Lactarius_indigo#Descriptionhttp://www.mushroomexpert.com/lactarius_indigo.html

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