Ink Stain Bolete

(Cyanoboletus pulverulentus)

Conservation Status


No Image Available

  IUCN Red List

not listed


NNR - Unranked


not listed


Ink Stain Bolete is a late season, blue staining mushroom. It occurs in eastern Europe and in North America. In the United States it occurs in the east from New Hampshire to North Carolina, west to Minnesota and Tennessee. It also occurs in the Pacific Northwest from Washington to northern California. In Minnesota it occurs only in the southeast quarter of the state. It is found in summer and fall in deciduous and mixed forests, in parks, and in gardens. It grows on the ground, alone, scattered, or in groups, usually under oak and beech trees, occasionally under conifers. It has a mutually beneficial relationship (mycorrhizal) with the tiny rootlets of trees, absorbing sugars and amino acids while helping the tree absorb water.

When it first appears, the cap is convex, dark brown to blackish-brown, and covered with fine, velvety hairs. As it ages it expands and the color lightens. Mature caps are broadly convex, hairless, and 1½ to 4 (4 to 10 cm) in diameter. The upper surface may be dry or moist. It sometimes develops cracks, revealing the yellowish flesh below, and develops reddish tints within the cracks. It quickly turns bluish-black when bruised.

The pore surface is yellow when young, becoming brownish-yellow as it ages. It instantly stains dark blue when bruised. There are 1 to 2 pores per millimeter. The pore tubes are angular and up to (15 mm) deep.

The stalk is solid, 1½ to 3 (4 to 8 cm) long, and to 1 (10 to 25 mm) thick. It is more or less equal from top to bottom but is sometimes tapered toward the base. The surface has raised ridges, but the ridges do not join and form a network (reticulate). The stalk is bright yellow at the top and reddish-brown to brown below. Like the cap, it quickly turns bluish-black when bruised. When sliced the flesh of the stalk rapidly turns bluish-black when exposed to air.

The flesh is mostly yellow, red just at the base of the stem. It instantly stains blue when exposed to air. The rapid, dark, bluish-black staining of the entire mushroom is the feature that gives the mushroom its common name. Some other boletes also stain blue but not as dramatically.

Ink Stain Bolete is edible but undesirable. A recent study (Braeuer et al., 2018a) showed that it hyper-accumulates organic arsenic, dimethylarsinic acid (DMA), from the soil. DMA is carcinogenic, so eating Ink Stain Bolete is not recommended.


Similar Species

Habitat and Hosts

Deciduous and mixed woodlands, parks, and gardens

Hardwoods, especially oak and beech; occasionally on conifers




Summer and fall


Distribution Map



4, 26, 29, 30, 77.





  Kingdom Fungi (fungi)  
  Subkingdom Dikarya  
  Phylum Basidiomycota (club fungi)  
  Subphylum Agaricomycotina (jelly fungi, yeasts, and mushrooms)  
  Class Agaricomycetes (mushrooms, bracket fungi, puffballs, and allies)  
  Subclass Agaricomycetidae  
  Order Boletales (boletes and allies)  
  Suborder Boletineae  


Boletaceae (boletes)  



This species was originally described as Boletus pulverulentus. It was transferred to the new genus Cyanoboletus in 2014.




Boletus pulverulentus

Tubiporus pulverulentus

Xerocomus pulverulentus


Common Names


Ink Stain Bolete

Inkstain Bolete (Brittain)










A symbiotic, usually beneficial relationship between a fungus and the tiny rootlets of a plant, usually a tree.





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Other Videos
  Mushroom time (cyanoboletus pulverulentus)

Aug 24, 2022

  Cyanoboletus pulverulentus
robert kozak

Aug 7, 2020

  Ink Stain Bolete Mushroom
Pine Creek Wildlife

Sep 5, 2022

When you slice or damage the flesh of an Ink Stain Bolete mushroom (Cyanoboletus pulverulentus), it turns blue!

They are considered edible too. I found this one in a mixed wood forest in Goodhue County, Minnesota, US.

  The Inkstain Bolete (Boletus pulverulentus)
Find In Nature - mycology, fungi

Dec 2, 2020

Found 3 mushrooms of Boletus pulverulentus (Inkstain Bolete). Every part of this Bolete change color when bruised. The yellow flesh turns blue instantaneously and after a few seconds it gets deep dark navy blue. Another scientific name is Cyanoboletus pulverulentus. 💚 If you enjoyed it don't forget to share, like and comment! That would help this channel a lot! 💚🙏




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Location: Saint Croix Bluffs Regional Park







Created: 7/19/2023

Last Updated:

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