How to identify Indigo Milk Mushroom

To correctly identify Indigo Milk Mushroom (Lactarius indigo), check each of these features in order. Misidentification is the most common cause of mushroom poisoning, so cross-reference multiple sources.

Step-by-step identification

1. 1

   Cap

   Shape, color, surface texture, and diameter.

   The cap is typically 5-15 cm in diameter, initially convex, becoming flattened to slightly depressed with age. The color is indigo blue when young, fading to a paler bluish-gray or grayish-brown with age. It may have darker concentric zones or spots. The surface is smooth and can be slightly sticky when moist.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   The gills are attached to slightly running down the stem (decurrent to slightly decurrent), closely spaced, and indigo blue. They may stain greenish where damaged.

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem is 2-8 cm long and 1-2.5 cm thick, equal or slightly tapering towards the base. It is indigo blue, fading with age, and may have pits or spots. The surface is smooth or slightly sticky.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is indigo blue, though this color fades when exposed to air. It may stain greenish when cut.

5. 5

   Fruiting body

   Overall growth pattern.

   Medium to large in size, with a distinctive indigo blue color when young.

6. 6

   Habitat

   Where it grows and on what substrate.

   Found in deciduous and coniferous forests, often under oak and pine trees. It forms mycorrhizal associations with these trees.

Key Facts

Cap surfaces

Smooth, slightly sticky when moist

Growth Form

Solitary or scattered

Spore Print

Cream to pale yellow

Body color

Indigo blue, fading to bluish-gray or grayish-brown

Odor

Mild, not distinctive

Flesh bruises

May stain greenish when cut

Height

2-8 cm

Cap Diameter

5-15 cm

Fruit body characteristics

• Gill attachment: Decurrent to slightly decurrent
• Stem shape: Cylindrical or slightly tapering
• Stem surface: Smooth or slightly sticky
• Ring: Absent
• Stem cross-section: Solid

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