Suillus intermedius
Description
Suillus intermedius is an edible species of mushroom in the genus Suillus. A pale yellow, glutinous Suillus, the margin appendiculate with yellow veil tissue, the context white to pale ocher; the stipe is pale yellow with dingy brown glandular dots. The glutinous annulus readily collapses, leaving an indistinct viscid zone on the stipe. It is found in North America, Costa Blanca Mountains-Spain.
Suillus acidus var. intermedius is a previous name. Suillus acidus Peck (1906) has a whiter cap. It may well be the same mushroom as Suillus intermedius—in which case Suillus acidus is the older name and should take precedence. The name Suillus intermedius may be officially invalid, due to a competing "Suillus intermedius," now known as Gyrodon intermedius.
Synonyms: Boletellus intermedius A.H.Sm. & Thiers (1971), Xerocomus intermedius (A.H.Sm. & Thiers) Heinem., Rammeloo & Rullier (1988).
Common names: Sour Cap Suillus.
Mushroom Identification
Ecology
Mycorrhizal with red pine and eastern white pine; growing alone, scattered, or gregariously; summer and fall; northeastern North America, the northern Midwest, and the Appalachian Mountains.
Cap
3.5–12 cm; convex at first, becoming broadly convex; thickly slimy when fresh; bald or sparsely, innately, radially fibrillose under the gluten; golden yellow to yellowish when young, darkening to dull orangish brown or golden brown; margin at first inrolled and attached to a whitish partial veil.
Pore Surface
Pale yellow when young; darker, dull yellow at maturity; not bruising; 2–3 roundish to angular pores per mm; tubes to 8 mm deep.
Stem
6–10 cm long; 5–13 mm thick; more or less equal; tough; whitish to yellowish below fine brown glandular dots that blacken with maturity; with age sometimes developing bright yellow areas near apex; when young with a thin, bracelet-like, gelatinous ring that dries out and flattens against the stem surface with maturity, appearing like a grayish zone; basal mycelium white.
Flesh
Whitish to pale yellow in the cap; darker yellow to orangish or rosy salmon in the stem; not staining on exposure, or sometimes staining pinkish.
Odor and Taste
Odor is not distinctive; the taste of the slime on the cap acidic or sour (or occasionally not distinctive).
Chemical Reactions
Ammonia negative to grayish or pinkish on cap surface; negative to purplish on flesh. KOH dark gray on cap surface; gray to bluish on flesh. Iron salts negative on cap surface and flesh.
Spore Print
Cinnamon brown.
Microscopic Features
Spores 7–10 x 2–4 µm; fusiform; smooth; hyaline to yellowish in KOH. Hymenial cystidia subfusiform; smooth; thin-walled; brown to brownish-purple. Caulocystidia 60–100 x 5–7.5 µm; cylindric to subclavate or subutriform; smooth; thin-walled; brownish-purple to yellow-brown in KOH.
Photo sources:
Photo 1 - Author: memebroom (CC BY-NC 4.0)
Photo 2 - Author: dylantomtaylor (CC BY-NC 4.0)
Photo 3 - Author: rangersara (Public Domain)
Photo 4 - Author: steven_dm (CC BY-NC 4.0)