Identification — FUNGAPHILIA

How to Recognise a Remarkably Blue Visitor

The Indigo Milk Cap is difficult to overlook. Its cap, gills, and stem may all display shades of blue, ranging from pale blue-grey to deep indigo. Older specimens may become faded, stained, cracked, or greenish, but they usually retain enough colour to look as though they have escaped from a fantasy field guide.

Its scientific name is Lactarius indigo. Like other milk caps, it can release a milk-like liquid when its gills or flesh are damaged. In this species, even the “milk” may be blue.

A beautiful colour is useful, but it is not a complete identification. Shape, habitat, surface texture, gills, latex, age, and regional variation should all be considered.

First Impression

What should I look for from above?

Young caps are rounded, with edges that may curve downward. As the mushroom grows, the cap becomes flatter and may eventually develop a shallow depression in the centre.

The surface often displays circular zones of darker and lighter blue. These rings can become less obvious with age, rain, dirt, or damage. Mature caps may also show greenish stains where the tissue has been bruised.

A fresh specimen can look polished and intensely coloured. An older one may look like it has survived several arguments with the forest floor.

Cap, Gills, and Stem

What is hiding under the cap?

Beneath the cap are closely arranged gills that run toward the stem. They may begin bright blue and later develop greenish marks after bruising or ageing.

The stem is usually short, sturdy, and coloured in blue tones similar to the cap. It may have small pits, marks, or darker patches across its surface.

When the gills or flesh are damaged, the mushroom may release blue latex. This is one of its most memorable features. The exposed tissue and latex can gradually shift toward green.

Please do not injure every mushroom you meet merely to see whether it performs this trick.

Handle With Caution

Is blue colour enough?

No single feature should be used alone to identify a wild mushroom. Lighting, age, weather, camera settings, and damage can all change its appearance. Other blue or blue-grey fungi may also occur in the same environment.

Record several features:

cap shape and surface pattern;

gill colour and attachment;

stem shape and texture;

colour changes after bruising;

surrounding trees and habitat;

photographs from above, below, and from the side.

This webpage is an appreciation guide, not an edible-mushroom certificate. Never eat a wild mushroom based only on photographs, colour, an application, or the confident opinion of a glowing website.