Are any slippery jacks poisonous?

"Are there poisonous slippery jacks?" is one of the questions beginners ask most. The answer is reassuring, but it needs a few caveats. In short: there are no deadly poisonous slippery jacks, but there are some nuances worth knowing.

The slippery jack (Suillus luteus and its close relatives) is rightly considered one of the safest mushrooms. But even the safest mushroom can harm you if it's picked or cooked the wrong way. Let's go through it all honestly.

No slippery jack is deadly poisonous

Let's start with the main point. The genus Suillus, which includes all true slippery jacks, has no deadly poisonous species. All of them are edible or conditionally edible, meaning they simply need proper preparation.

That makes the slippery jack a great mushroom for anyone still learning. Unlike gilled mushrooms, which include the deadly amanitas, the pored slippery jack has no dangerous lookalike in Ukrainian forests.

So if you've confidently identified a slippery jack by its slimy cap and spongy underside, poisoning yourself with it is practically impossible. Danger comes only from a mistake in identification or from mishandling the mushroom.

When even an edible slippery jack does harm

Now for the nuances. Even a safe mushroom can cause trouble in a few situations.

• Old mushrooms. Overmature slippery jacks with a darkened pore surface build up breakdown products and are hard to digest. Take only young, firm specimens.
• Wormy mushrooms. Slippery jacks infested with maggots spoil quickly. It's better to leave them in the forest.
• Mushrooms near roads and factories. Slippery jacks soak up heavy metals from the soil like a sponge. Don't pick them near highways or industrial zones.
• The slimy skin. In some people it causes a mild stomach upset, which is why it's usually peeled off.

As you can see, it's not the slippery jack itself that does harm, but careless picking or cooking. That goes for any mushroom, even the very best.

"False slippery jacks": should you be afraid?

You may sometimes hear about "false slippery jacks." This usually doesn't mean poisonous mushrooms, just less tasty relatives or neighbors in the pine woods.

• **Bovine bolete** is often called a "false slippery jack" because of its drier cap, but it's perfectly edible.
• Peppery bolete is a small pored mushroom with a burning, bitter taste. It isn't poisonous, but it ruins a dish with its flavor.

None of these mushrooms is life-threatening. The worst that can happen is a bitter peppery bolete in your pot. So a "false slippery jack" is a matter of taste, not safety.

How to pick slippery jacks safely

To keep your forays worry-free, follow a few simple rules.

1. Take only mushrooms with a spongy underside, not gills.
2. Choose young, firm specimens with light-colored pores.
3. Avoid roadsides, factories and dumps.
4. Don't mix mushrooms you've confidently identified with doubtful ones.

The best time to look for slippery jacks is a day or two after a warm rain in coniferous and mixed forests. An easy way to track good windows is our mushroom radar: it shows when moisture and warmth line up well for mushrooms to appear.

Caution never hurts

The slippery jack is safe, but the golden rule stays the same for any mushroom: if in doubt, leave it out. The habit of checking for a spongy underside and taking only young, clean mushrooms will make the slippery jack what it should be: a reliable and tasty find.

Sources

• "Field Guide to the Fungi of Ukraine" (Kyiv, Naukova Dumka publishing house).
• Suillus luteus on GBIF, the global biodiversity database.
• Suillus on MycoBank, the international fungal nomenclature database.
• Suillus luteus on Wikipedia.