Gilled boletes are a group of fungi that resemble the well-known pored boletes but the spore-bearing surface is gill-like rather than pored.
The term ‘bolete’ refers in common usage to the pored boletes, and includes the genera Boletus, Leccinum, and Suillus among others. On the underside of the caps of these mushrooms is tissue consisting of soft vertical tubes. The tubes can be separated from the firmer cap flesh above it by wiping it off with a finger. The lower end of the tubes forms a pore surface that makes these mushrooms easy to distinguish from gilled mushrooms.
A smaller group within the order ‘Boletales’ have gill-like structures instead of tubes. The gill-like structure can usually be separated from the firmer cap flesh above it, in the same way that the tubes can be separated in pored boletes.
These gilled boletes have long been considered related to pored boletes because of structural similarities. The spores in some cases are also similar to spores of pored boletes. Molecular studies have so far supported their inclusion in Boletales. Tapinella is one genus which has been separated from the Boletales despite its similarities to Paxillus in particular.(1)
The gilled boletes are not a uniform group. Spore deposit varies from blackish (Chroogomphus, Gomphidius) to whitish (Hygrophoropsis) to shades of brown (Paxillus, Phylloporus). The veil is fibrillose (Chroogomphus), glutinous with a fibrillose inner layer (Gomphidius), or absent (Hygrophoropsis, Paxillus, Phylloporus).
Most amateur mycologists will recognize the genera quite easily without the need of a key to separate them from other gilled mushrooms. Keying them out with a gilled mushroom key is more difficult than learning to recognize them by sight. Gomphidius subroseus, Chroogomphus tomentosus, Hygrophoropsis aurantiaca, and Paxillus involutus are all common distinctive mushrooms. (Chanterelle seekers soon learn to distinguish Chroogomphus tomentosus and Hygrophoropsis aurantiaca which are chanterelle look-alikes.(2) ) The uncommon genus Phylloporus is distinctive as well.
The species within the gilled bolete genera can be more difficult to distinguish.
Gomphidius - slimy, convex cap; whitish flesh; soft, somewhat waxy, decurrent gills that are whitish when young; stem typically whitish in upper part, often yellowish at base, and turning black with handling; veil slimy with inner fibrillose layer; growing on the ground associated with conifers; spore deposit smoky black; spores narrowly elliptical and smooth; pleurocystidia cylindric. See Key to Gomphidiaceae.
Chroogomphus - dry to slimy, convex cap; pink to orange flesh; decurrent gills orange or ochraceous when young; fleshy stem; veil fibrillose; smoky olive to black spore deposit; spores long, elliptic to spindle-shaped, smooth. See Key to Gomphidiaceae.
Hygrophoropsis - orange to brown cap, gills, and stem; cap 1-10 cm, with inrolled margin when young, becoming flat to funnel-shaped, cap surface dry, often felty; gills thin and forked to somewhat vein-like; stem central to off-center; veil absent; spore deposit whitish; spores elliptic, smooth, often dextrinoid.
Paxillus - cap 5-20 cm, convex to depressed, may be viscid when moist (but otherwise dry), margin of cap usually inrolled when young; decurrent gills often veined or poroid near stem, typically yellowish brown to ochraceous brown and often staining darker brown when bruised; stem central to off-center, brownish; veil absent; fruiting on ground or on wood; dark yellow-brown to cocoa-brown spore deposit; spores mostly elliptic, smooth.
a. Spore deposit yellowish brown to rust brown; cap 4-15(20) cm across, dull brown to yellow-brown or reddish brown, staining darker, when young deeply inrolled; fruits under birch in urban settings, less often in forest, summer and fall; common
b. Spore deposit darker (vinaceous brown, cinnamon brown, reddish brown, chocolate brown); cap averages larger (5-20 cm across), dingy buff to pale yellowish brown staining darker, when young less deeply inrolled; fruits under aspen, also poplar, birch, oak, sometimes in mixed forest, spring to early fall; rarely identified in the Pacific Northwest
Phylloporus - cap 3-12 cm, convex becoming flat, velvety to subtomentose, dull reddish, reddish brown, or with olivaceous brown hues; gills typically bright yellow to yellow-green, often anastomosed or poroid, separable from cap; stem dry and fleshy; veil absent; spore deposit olivaceous brown; spores spindle-shaped to nearly cylindric, smooth; cheilocystidia and pleurocystidia typically numerous
a. Gills decurrent, may stain blue; cap dull brown, olive-brown, yellow-brown, red-brown, or red; pileipellis stains blue with application of NH4OH (at least in the subspecies that does not stain blue with bruising)
b. Gills adnexed to subdecurrent, do not stain blue; cap olive-brown to olive-yellow; pileipellis stains violaceous fuscous, then quickly mahogany-red with application of NH4OH
Hygrophoropsis aurantiaca (Wulfen ex Fr.) Maire false chanterelle
|CAP 2-8(14) cm across, convex becoming flat to funnel-shaped, margin at first inrolled; orange, brown-orange, yellow-brown, olive-brown, or dark brown, varying to whitish or blackish; dry, smooth to felty, margin ribbed at times but not striate; flesh thin, pallid or tinged cap-color. GILLS decurrent, close, thin (may be blunt when young), narrow, usually forked dichotomously several times; orange, usually brighter than cap. STEM 2-10 cm x 0.3-1.2 cm, central or off-center, equal or enlarged toward base; yellowish to orange or colored like cap; dry, smooth to felty. VEIL absent. HABITAT humus or rotting wood, usually associated with conifers. SPORE DEPOSIT white to cream. MICROSTRUCTURES spores 5-8 x 2.5-5.5 um, elliptic, smooth, often dextrinoid; pleurocystidia and cheilocystidia none. REMARKS Principal fieldmarks are orange to brown cap and stem, decurrent, orange, dichotomously forked gills, and white spore deposit; common in Pacific Northwest.||Hygrophoropsis aurantiaca|
Kit Scates Barnhart
Paxillus involutus (Batsch) Fr. inrolled pax
|CAP 4-15(20) cm across, convex with strongly inrolled margin, then flat to depressed; dull brown to dingy yellow-brown, olive-brown, or dingy reddish brown, often with darker brown stains; viscid when moist, smooth or with soft matted hairs, margin often obscurely ribbed; flesh thick, buff to yellowish, staining reddish to brown when cut. GILLS decurrent, close or crowded, broad, often forking, often anastomosing near stem; pallid to yellowish becoming dingy yellow to olive or brownish, staining dark brown or reddish brown. STEM 2-7(10) cm x 0.5-4 cm, usually shorter than width of mature cap, central to somewhat off-center; cap-colored or paler, often with dingy reddish to dark brown stains; dry, smooth. VEIL absent. HABITAT associated with birch in parks and landscaped areas, also associated with aspen, less commonly found in forest or boggy areas. SPORE DEPOSIT yellow-brown to rust brown. MICROSTRUCTURES spores 6.6-10 x 4-6.7 um, elliptic, smooth, inamyloid; pleurocystidia and cheilocystidia fusiform with brown contents. REMARKS Common. Features include dingy brown inrolled cap, short stem relative to cap, staining of all parts brown to reddish brown when handled or when old, fruiting under birch in urban settings, less often in forest, summer and fall, and spore deposit yellowish brown to rust brown.||Paxillus involutus|
Paxillus vernalis Watling spring Paxillus
|CAP 5-20 cm across, convex with inrolled margin, then flat to depressed; dingy buff to yellow-brown, staining red-brown; dry, smooth or with soft matted hairs; flesh thick, whitish to buff or yellowish, staining darker. GILLS decurrent, close, narrow, sometimes forking, also anastomosing near stem; dingy buff to pale yellow-brown, staining red-brown, when old dingy brown. STEM 3-10 cm x 0.5-4 cm, yellow to cinnamon brown, staining red-brown, when old dark brown; dry, fibrillose. VEIL absent. HABITAT under aspen, also under birch, poplar, oak, sometimes in boreal mixed forest, spring to early fall. SPORE DEPOSIT vinaceous brown, cinnamon brown, reddish brown, chocolate brown. MICROSTRUCTURES spores 6.5-9.0 x 5.0-6.5 um, elliptic, smooth. REMARKS Rarely identified in Pacific Northwest. Features include large buff to yellow ocher cap, short stem relative to cap, red-brown staining of all parts, fruiting from spring to early fall usually under hardwoods (especially aspen), and spore deposit vinaceous brown, cinnamon brown, reddish brown, or chocolate brown.||Paxillus vernalis|
Phylloporus arenicola A.H. Sm. & Trappe
|CAP 1.5-4.5 cm across, convex becoming nearly flat to somewhat depressed; dull olive with a darker disc when young, becoming olive-brown to olive-yellow; dry, unpolished to velvety; flesh whitish to yellowish, not staining blue. GILLS adnexed to subdecurrent, subdistant, broad; yellow, not staining. STEM 4-6 cm x 0.6-0.8 cm, dull yellow ground color overlaid with brown to reddish dots, bright yellow in and around the base or in some becoming cinnabar toned; dry. VEIL absent. HABITAT on sand dunes under pine, probably other habitats, fall. SPORE DEPOSIT color not documented. MICROSTRUCTURES spores 9-12 x 4-5 um, subelliptic to subfusoid, smooth, weakly dextrinoid; pleurocystidia and cheilocystidia subfusoid to fusoid-ventricose. CHEMICAL REACTIONS NH4OH applied to cap cuticle immediately produces a violaceous-fuscous stain which soon becomes mahogany red. REMARKS Features include dry olive to olive-fuscous cap, whitish to yellowish flesh, adnexed to subdecurrent, yellow gills without blue staining, yellow stem overlaid with brown to reddish dots, and growth favoring sand dunes.||Phylloporus arenicola|
Kit Scates Barnhart
Phylloporus rhodoxanthus (Schwein.) Bres.
|CAP 2-12 cm across, convex becoming flat or somewhat depressed, dull brown, olive-brown, yellow-brown, red-brown, or dull red; dry, nearly smooth to velvety; flesh whitish to yellowish. GILLS adnate to decurrent, subdistant to distant, broad, sometimes forked, sometimes pore-like near stem; bright yellow to ocher, may bruise green or blue, may stain brownish, with strong gill-like structures. STEM 3-10 cm x 0.4-1.5 cm, yellow to dingy yellowish with reddish tinges, often stained dingy brown or reddish-brown in lower part; smooth, dry, often with distinct ribs near top, with small reddish brown dots and points. VEIL absent. HABITAT on the ground in forests. SPORE DEPOSIT brown to yellow-brown, orange-brown, or olive-tinged brown. MICROSTRUCTURES spores 8-15 x 3-6 um, narrowly elliptic to fusoid, smooth. CHEMICAL REACTIONS cap cuticle stains blue with NH4OH at least in subspecies americanus (this subspecies does not stain blue with injury). REMARKS Features include dry, brown to reddish cap, adnate to decurrent yellow gills that may stain green or blue, yellow stem with reddish or brownish tinges and reddish brown dots, and growth on the ground.||Phylloporus rhodoxanthus|
(1) The Eighth Edition of Ainsworth & Bisby’s Dictionary of the Fungi (1995), synonymized Tapinella with Paxillus in Paxillaceae (Boletales). The Ninth Edition (2001) gave the genus independent status in Hygrophoropsidaceae (Boletales). The Tenth Edition (2008) transferred it to Tapinellaceae (Agaricales). For descriptions of Tapinella atrotomentosa ( = Paxillus atrotomentosus) and Tapinella panuoides ( = Paxillus panuoides), see Key to Keys.
(2) Compared with Cantharellus formosus (Pacific golden chanterelle), Chroogomphus tomentosus has a cap that is rounder in outline from above and less wavy from the side, orange flesh, thin gills rather than blunt folds, and blackish spores. Hygrophoropsis aurantiaca has a cap that is not as wavy or frilled as in Cantharellus formosus, cap color that is often browner, thinner more crowded gills (may be blunt when young) that are usually more orange than in C. formosus, and flimsier flesh.
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