The caps may be brown, yellow, or reddish, while the pores are often yellowish. Although many Suillus species have distinctive features, some can be difficult to identify.
Before modern DNA research, Suillus was classified in the same family as many other boletes, called Boletaceae.
Later studies showed that it belongs to a separate family, Suillaceae, but it is still part of the larger Boletales group of mushrooms.
The genus Suillus includes more than 100 species worldwide, although the exact number varies among scientific sources as researchers continue to study and classify these mushrooms.
Slippery Jack and other mushrooms of the Suillus genus are widely distributed throughout the Pacific Northwest. These fungi grow on the ground, forming associations with coniferous trees such as pines, spruces, and Douglas-firs.
Several species of Suillus are edible, although their culinary quality varies. Some are considered mediocre in flavor, while others are highly valued in certain regions.
Slippery Jack is particularly popular in Eastern Europe. Known as maslyata in Russian and maślaki in Polish, these mushrooms are often called "butter mushrooms." They are used in traditional Polish and Russian cuisines and are prepared in various ways, including pickling, preserving, and sautéing.
However, some Suillus mushrooms have a bitter or acidic taste, and certain species can cause gastrointestinal upset. Slippery Jack has been associated with illness in some people, even when eaten as food. Removing the slimy skin from the cap is a common preparation recommendation, although it does not guarantee that the mushroom will be tolerated. Rarely, an allergic reaction may occur.
Slippery Jack (Edible)
Slippery Jack (Suillus luteus) is an edible wild mushroom with a mild aroma and a flavor appreciated by many mushroom collectors. It is commonly used for pickling, preserving, or sautéing. Because of its high water content, it may become soft during drying.
A common recommendation for preparing this species is to remove the slimy skin before cooking. Even with proper identification and cooking, some people may still experience gastrointestinal upset.
Cap: Hemispherical when young, becoming broadly convex to nearly flat with age. Sticky or slimy when moist, yellow-brown to reddish-brown; 2–5 inches (5–12 cm) wide. 2-5 inches (5-12 cm) wide.
Cap's Underside: Sponge-like, with small, rounded pores. Whitish to yellow when young, becoming darker with age and usually not changing color when bruised.
Spore Print: Brown. Spores are elliptical.
Stem: Thick and whitish to yellowish, often with brown spots or fibers. A whitish partial veil forms a ring around the upper stem; 1–5 inches (3–12 cm) long.
Flesh: White to pale yellow, becoming more yellow with age.
Fruiting: Usually grows in groups.
Habitat: Found on the ground in coniferous forests, especially beneath or near pine trees. It may also occur in lawns or other grassy areas near pines.
Season: September to December.
Similar species include Granulated Suillus (Suillus granulatus) and Short-stemmed Suillus (Suillus brevipes). Unlike Slippery Jack, these species lack a partial veil or a ring on the stem.
Fat Jack (Edible)
Fat Jack (Suillus ponderosus), also known as Douglas-fir Suillus, is an edible wild mushroom with a rich flavor. It occurs along the West Coast and is found on the ground in forests or along their edges, associated with Douglas-fir trees.
Fat Jack can be used for pickling, preserving, or sautéing. As with other Suillus species, careful identification and thorough cooking are important.
Cap: Hemispherical when young, becoming broadly convex to nearly flat with age. Sticky when moist, yellowish-brown to brown; 2-10 inches (5-25 cm) wide.
Cap's Underside: Sponge-like, with yellowish to olive-yellow, small angular to subangular pores. The pores darken with age and may stain brown when bruised.
Spore Print: Brownish. Spores are elliptical.
Stem: Solid, yellowish above the ring and orange-brown below. A partial veil forms a ring around the stem. The lower stem lacks glandular dots; 1–4 inches (3–10 cm) long.
Flesh: Yellowish, becoming reddish to brownish when bruised or cut.
Fruiting: Usually grows in groups.
Habitat: Mycorrhizal with Douglas-fir and commonly found beneath or near Douglas-fir trees.
Season: September to December.
Matte Jack (Edible)
Matte Jack (Suillus lakei), also known as Western Painted Suillus or Lake's Bolete, is an edible wild mushroom. Characterized by reddish-brown to brown scales or fibers on its cap, it is found in forests and along their edges, where it grows in association with Douglas-fir trees.
Matte Jack is found throughout parts of the Pacific Northwest and other areas of western North America. It can be used for pickling, preserving, or sautéing.
Cap: Hemispherical when young, becoming broadly convex to nearly flat with age. Dry and scaly, reddish-brown to brown; 2-6 inches (5-15 cm) wide.
Cap's Underside: Sponge-like, with yellow to brownish pores that may darken with age.
Spore Print: Brownish. Spores are elliptical.
Stem: Solid, yellowish above the ring and streaked with reddish-brown below. A partial veil forms a ring around the stem when young; 1-3 inches (2-7 cm) long.
Flesh: Yellowish, staining blue to blue-green when bruised or cut.
Fruiting: Grows singly or in groups.
Habitat: Mycorrhizal with Douglas-fir and commonly found beneath or near Douglas-fir trees.
Season: September to December.
It's smart to purchase one or two pocket mushroom guides to cross-reference. Make sure the identification book is up to date and relevant to your area. Never rely on a single photograph or a general description to identify a wild mushroom.
The good choice is:
National Audubon Society Field Guide to North American Mushrooms
All That the Rain Promises and More: A Hip Pocket Guide to Western Mushrooms
🟡 Wild mushroom safety: Eat wild mushrooms only when they have been positively identified as an edible species. Suillus Mushrooms should be thoroughly cooked before eating.
Methods of Cooking and Preservation
Suillus mushrooms can be sautéed, pickled, or preserved. Some species can also be dried or frozen, although the results may vary depending on the species and the mushrooms' condition.
Do not keep freshly harvested mushrooms for a long time before preparing them. Use young, firm specimens and discard any that are deteriorating or showing signs of decay. Carefully clean the mushrooms and remove the brown, sticky skin from the caps of Slippery Jack.
In older mushrooms, check the spongy pore layer for insect damage. If it is soft, deteriorating, or heavily infested, remove it or discard the mushroom.
The mushrooms are commonly boiled before being added to a vinegar-based marinade.
Poor Man's Slippery Jack (Inedible)
Poor Man's Slippery Jack (Suillus tomentosus), also known as Woolly-capped Suillus or Blue-staining Slippery Jack, has a yellow to orange-brown cap covered with fibrous scales. The spongy pore layer is yellowish to cinnamon-colored. The stem is yellow to orange, thick, and may be club-shaped.
This mushroom grows on the ground in mountain ranges and coastal forests, mostly near or under two-needle pines.
It can have an acidic taste and may cause gastrointestinal upset in some people.
Poor Man's Slippery Jack can also resemble other blue-staining species, including poisonous species, so careful identification is important before considering it for consumption.
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Disclaimer
This is not an official guide to wild mushroom foraging. Please do your own research and learn from an experienced mushroom expert before collecting or consuming any wild mushrooms.
Before you begin foraging, learn to accurately identify both edible and toxic mushrooms. Never consume a wild mushroom unless you are certain of its identification and edibility. Follow proper preparation and cooking instructions for each species, as some edible mushrooms must be thoroughly cooked before consumption. Be aware that even correctly identified edible mushrooms can cause adverse reactions in some people.
I can’t see the underside of the caps in the bottom left corner picture at the top of the page, in the group of 4.
However, I think that you’ve mistakenly included a picture of Gomphidius oregonensis there.
While edible and not terrible eating, I don’t think they would be included with Suillus since they’re a gilled mushroom.