Smell

Resinous

Walking through a conifer forest, foragers often notice the rich scent of pine resin. But sometimes that resinous smell comes not from the trees themselves but straight from the mushrooms growing beneath them. A resinous smell is a specific and fairly rare trait among macromycetes.

1 species in the database.

Saffron milk cap
Lactarius deliciosus
Edible

How mushrooms acquire a resinous smell

A smell of resin (pine needles, turpentine) in mushrooms is most often linked to their mycorrhizal symbiosis with conifers. Essential oils and terpenes, abundant in pine or spruce roots, can build up in the mushroom's fruiting body.

M.Ya. Zerova in «Key to the Fungi of Ukraine» and Roger Phillips describe several striking examples of mushrooms with a resinous aroma:

1. Slippery jack (Suillus luteus): The cap skin of this mushroom, thickly coated in slime, often has a light but distinct smell of pine resin. The aroma lingers even on the forager's hands after cleaning the mushrooms.

2. Tricholoma pessundatum: A poisonous (or strongly inedible) mushroom that grows in large numbers in pine forests in autumn. It has a red-brown cap and a pronounced, slightly bitter smell of pine needles, resin or fresh wood.

3. Slimy spike (Gomphidius glutinosus): This slimy edible mushroom often smells of spruce resin and damp forest.

4. Red-belted conk (Fomitopsis pinicola): This large wood-decaying fungus, growing on dead conifers, exudes droplets of liquid (guttation) with an extraordinarily strong and pleasant smell of fresh pine resin.

What it means for the forager

David Arora notes that a resinous smell on its own is not an indicator of edibility or toxicity. However, it almost always points to a close ecological tie between the mushroom and conifers. If you find a mushroom with a resinous smell in a pure oak forest (without a single pine), you have most likely mistaken some chemical or phenolic odor for resin — and that is a dangerous sign.

Questions and answers

Why do your hands smell of resin and turn black after cleaning slippery jacks?

The slime coating a slippery jack's cap contains substances chemically close to pine resin. They don't wash off with plain water, they oxidize in the air (which is why your hands turn black) and leave a lingering, tart smell of resin.

Can you eat knights that smell strongly of resin?

Most brown and reddish knights (Tricholoma) that grow in pine forests and have a sharp smell of resin or dust are toxic. They cause severe gastrointestinal upset. The exception is the yellow knight (Tricholoma equestre), but its smell is more mealy than resinous.

Does the resinous smell disappear when you cook slippery jacks?

Yes, most light terpene smells (pine needles, resin) evaporate during cooking. To make slippery jacks tastier and less bitter, always peel the slimy skin off the cap (the main carrier of the smell) before cooking.

Sources

1.Зерова М.Я. та ін. Визначник грибів України. 1979
2.Roger Phillips. Mushrooms (Roger Phillips)
3.David Arora. Mushrooms Demystified
4.Index Fungorum