Slippery Jacks

Welcome back to Mushroom Monday, your weekly look at some of PEI’s fascinating fungi.  Today we have not one species but a whole group that’s both reasonably easy to identify and edible: Suillus species, many of which are called Slippery Jacks.

The first thing you’ll notice about a Slippery Jack is the feature that gives it that common name: a somewhat slimy or sticky cap. These mushrooms do indeed look slippery, especially after rain.

Peek under that cap and you’ll see Slippery Jacks are boletes, a term commonly used to describe mushrooms with spongy pores rather than gills, teeth, or folds. There are gilled boletes – the Brown Roll-rim (Paxillus involutus) we looked at in September is one example – but Slippery Jacks meet expectations and have pores.

On young Slippery Jacks, those pores are often protected by a partial veil: tissue connected to the outer edge of the cap and the stem that covers the pores until they mature. As the mushroom grows and the cap expands, the partial veil tears apart and you can often find its remnants on the edge of the cap or as a ring on the stem.

Look carefully at the stem of a Slippery Jack and you may also see tiny glandular dots that feel slimy to the touch. Those are the ends of specialized cells, but mycologists aren’t entirely sure what they’re for. Theories include protecting the mushroom from drying out, getting rid of metabolic waste, or preventing insects from eating the spores before they’ve had a chance to disperse. Not all Suillus species have them, but – whatever their purpose – they help with identification when they’re present.

Cap colour among Slippery Jacks can vary from yellow to brown to reddish. Not every Slippery Jack will have every trait but – in general – a mushroom with a slimy or sticky cap, pores, and a ring on the stem is likely a member of this group. Consider it a bonus if you can see dots on the stem.

Slippery Jacks are mycorrhizal fungi, forming mutually beneficial relationships with trees. Many are host-specific, so knowing what trees your Slippery Jack was growing with is an important key to figuring out exactly which of the dozens of Suillus species you have. Other features to look for are the size and shape of the pores, whether the flesh changes colour when cut or bruised, and whether the stem is hollow or solid inside.

The Suillus shown here was associated with Larch (Larix laricina), has a brown cap, yellow pores that bruise reddish-brown (you can see that colour change where my fingers pressed the pore surface), and a solid stem with a ring. This all points to Tamarack Jack (Suillus clintonianus), the most commonly-reported member of this group on PEI. (Tamarack is another name for Larch; Larch Jack just doesn’t have the same ring to it!)

All Suillus species are edible though not all are palatable. Look for younger, firm specimens, and peel the caps to remove the slimy layer – it can cause stomach upset in some people. As with any wild mushroom, be sure to cook your Slippery Jacks well before eating.

Most of our species, including Tamarack Jack, are fall mushrooms. They can often be found in large numbers along woodland roads and trails, so watch for them as you explore PEI Untamed!