|Expert links:||Stemmed||Odd Pores||Soft|
|Big Bracket||Small Bracket||Effuso-reflexed||Resupinate|
Hard or tough mushrooms that you wouldn't want to chew on. In fact, some of them are easily mistaken for the piece of wood they are growing out of. The pores they have range in size from very small to very large and sometimes are oddly shaped like a maze or ragged teeth. Some pores are so small they can't be seen without a hand lens, but you should suspect every mushroom that is as tough as wood of possibly having pores. Crusts growing flat on wood that are smooth or wrinkled or tooth-like with small teeth <3mm are to be found on that page.
The shapes can be quite variable. Some are bracket-like (sticking straight out of the side of the log) and can be anywhere from applanate (thin like a dinner plate) to hoofed (taller than wide). On the other end of the spectrum some are simply a pore suface lying resupinate (effused) or flat on the wood. In between are those called effuso-reflexed, where some pores lie flat on wood and the edge peels away from the wood to form a cap.
The really thin ones resemble pieces of leather, while most are thicker and resemble blocks of wood. Some species are softer and can easily be torn. What makes some of them so tough is that instead of having one kind of hyphae, or thread-like cell (generative hyphae) throughout the mushroom whose main function may be to transport nutrients around, some polypores have evolved two (dimitic) or three (trimitic) kinds - generative, binding and skeletal hyphae. The extra kinds may be meant to reinforce the mushroom and make it tougher and less susceptible to rotting. Indeed, it is often joked that when no other mushrooms are around, you can always find polypores, because they may not rot for years. Many of them are also perennial, adding a new layer of pores (and possibly cap) on top of the old ones year after year. While many mushrooms might only live for a few hours or days, some polypores can live for decades. Next time you wonder why Fomitopsis pinicola is the most common mushroom in the PNW, remember that every one of them that has ever grown in the last generation or so is probably still there. Most species are saprophytic, except for a few exceptions that will be noted. The main order is the Polyporales. In fact, every polypore used to be called Polyporus <something> (just like every gilled mushroom used to be called Agaricus <something>). There is a second order that specializes in polypores (usually the darker fleshed ones), the Hymenochaetales, and a few additional orders have produced a few polypore-like mushrooms as well. Many polypores have green tones, but this is usually just algae growing on the polypore and will be noted when it is common.
Some polypores are said to have medicinal qualities, but you would break your teeth on them if you tried to eat them, so people have cheese grated pieces into hot water to make a tea. Don't do this indiscriminately. There aren't a lot of known poisonous polypores, but some are.
A note about the chemical tests... more species turn colours (like red in KOH) than I have noted. Not all of them have been tried. So don't worry if your polypore turns colour and I didn't say it was supposed to. Until more complete experimentation is done, chemical tests will only be so useful.
|Some species are "artist" conks (Ganoderma is especially famous for this). Wherever the pores are touched they stain from whitish to brownish (or reddish), so much so that you can draw quite striking artwork on them. If your polypore pores turn dark when you scratch them, consider the following genera: Ganoderma, Ischnoderma, Phellinus, Coltricia, Inonotus, Abortiporus and Bjerkandera for brackets, and Physisporinus and Ceriporia for resupinates.|
Key to Polypore groups, showing the background colour of the section to help you not get lost.
Stemmed polypores - these are most likely to be mistaken for boletes, but the pore surface cannot easily be removed from the bottom of the cap. Some are found on the ground. The stem is sometimes lateral, but usually somewhat underneath the cap or off centre.
1. Pale pores that don't darken when touched.
(a) Thick fleshed, on the ground. Often colourful.
Albatrellus s.l. - these most resemble regular "cap and stem" mushrooms, and are usually larger and thicker fleshed (up to 10cm or more across) than the wood-inhabiting Polyporus. The pores are pale. They are found on the ground and are probably mycorrhizal and are actually in the Russulales (at least most of the ones in the PNW are). A. flettii, A. confluens and A. subrubescens have amyloid spores like Russula; however, the spores are smooth and elliptical. While most of these are still commonly called Albatrellus, they have recently been moved to new genera to reflect the more subtle relationships between them.
A. (Albatrellopsis) confluens - confluent caps pinkish-orange to brown, much like Osteina obducta but on the ground. <10cm
A. (Polypus) dispansus - crazy rosettes of caps <5cm each. Compare Bondarzewia etc.
Two unrelated stemmed polypores. One is saprophytic. Polyporus tuberaster, below, may be found on the ground growing from a sclerotium.
Jahnoporus hirtus - brown velvety cap and stem, smells like iodine! Bitter! Saprophytic. Related to Oligoporus. <15cm.
Stemmed rosettes (Bondarzewia etc.) - growing as multiple caps, but from wood or buried wood near tree trunks. Bondarzewia is also related to Russula. Grifola/
Meripilus and Oligoporus are considered "regular" polypores in the Polyporales.
Bondarzewia occidentalis ('mesenterica'/'montana') - large single or multiple orange-brown caps, stem central to lateral, <25cm. Like Russula, it has amyloid, spiny spores.
Grifola frondosa - "hen of the woods" cluster of many ~5cm fan-shaped caps with eccentric stems.
Meripilus sumstinei (giganteus) - stains black where touched.
Polyporus umbellatus - round instead of fan shaped caps. They prefer hardwoods.
Osteina (Oligoporus) obducta - like Albatrellus confluens but on wood, soft when fresh but dries bone hard. <12cm
1(c) On wood, usually thin fleshed. (The thick-fleshed Jahnoporus, above, may sometimes grow on wood, as it is saprophytic too.)
Polyporus - smaller, thinner (somewhat leathery) "cap and stem" looking mushrooms, usually on wood, with white pores. 5-10cm, but some are larger. The heart of the regular polypore order, Polyporales. Unfortunately, the first one named (Polyporus tuberaster) turned out to be somewhat genetically distinct from the rest of them, so most are undergoing name changes to new genera.
P. (Picipes) badius - concentric orange cap, black stem, on wood. Very small pores. <15cm.
P. (Picipes) melanopus - on the ground, <10cm
P. (Cerioporus) elegans (leptocephalus) - tan, some of stem black, turns white in age.
P. (Cerioporus) varius - may have dark radial streaks.
P. (Cerioporus) cryptopus (rhizophilus) - white cap, stem
P. (Lentinus) brumalis - dark brown cap, paler stem. Cap margin with finer hairs than P. arcularius. Prefers birch.
P. (Neofavolus) alveolaris - scaly orange cap, very large diamond shaped pores. Often off-centre stem. On hardwoods.
|P. umbellatus - much like Grifola but with round caps and more central stem on each one.|
2. Pores darker or darken when touched
Onnia - stemmedmushrooms with non-white pores that often darken when touched. They turn black in KOH. Up to 10cm or more wide, on wood or the ground. These actually belong to the "other" order of polypores, the Hymenochaetales. Coltricia may be mycorrhizal. Onnia is parasitic, and has setae (see Phellinus). Unrelated "artist" stemmed polypores are in the following section.
Coltricia perennis - concentric orange cap, thin leathery flesh, on the ground. Artist.
C. cinnamomea - smaller <4cm, less zoned. Shinier, less hairy cap. Hardwoods.
C. montagnei - concentric rings instead of pores underneath!
Onnia (Inonotus) tomentosa - usually yellower cap, usually less zoned. Thicker flesh. Artist. Near spruce.
Inonotus spp are found on wood without stems.
Abortiporus biennis - perhaps with shingled, zoned, white to brown furry caps, or just misshapen aborted bodies with odd maze-shaped pores that blush red when touched. <20cm on hardwoods.
Phaeolus schweinitzii - "dyer's polypore", odd yellow-green pores that turn brown. <30cm. Used to dye clothing. Black in KOH.
Ganoderma oregonense grp - varnished artist conk. <30cm
If your odd pored mushroom is soft (easily torn or gelatinous) look for it under that group instead. This section is for mushrooms with the consistency of wood or leather.
First, those resembling gills.
Schizophyllum commune - "split gill", in the Agaricales but evolved to be tough instead of the other way around. Each gill is split in half lengthwise. <5cm. Very thin and leathery.
Gloeophyllum sepiarium - red or orange brown hairy cap. Distant gills. <10cm, may be on timber. In the Gloeophyllales.
G. trabeum - crowded gills.
Other G. species are not gilled. All black in KOH.
|Trichaptum laricinum -
purple gills underside when young, usually effuso-reflexed. Resembles T.
biforme and T. abietinum. On conifers.
Coltricia montagnei - like C. perennis but with concentric "gills" under the cap!
Sometimes the pores are ragged, almost like teeth. Even those in the section after this one whose pores are typically elongated can often look ragged too, so try that section as well.
Echinodontium - dark teeth underneath (but often just a tattered mess), bright red-orange inside, found on the tooth page.
Trichaptum biforme - <5cm, leathery, purplish, may have tooth-like pores. Hardwoods. (See. T. abietinum).
Schizopora paradoxa - white, grows flat on wood. Compare Antrodia and Irpex. Usually hardwoods.
Phaeolus schweinitzii - large rosettes with short stem, on or near wood. Yellow-green tattered pores bruise brown. Dyeing mushroom. Up to 30cm! Black in KOH.
Pycnoporellus alboluteus - beautiful shades of orange, large, irregular tall pores. Spring. Turns red in KOH.
Irpex lacteus - whitish, like Schizopora paradoxa, but its usually tattered toothy pores are slightly different, and it's not fully resupinate but effuso-reflexed. Usually on hardwoods. Hymenochaetales. Plicatura nivea is merely wrinkled underneath its cap.
Steccherinum ochraceum - actual spines, yellow-orange when fresh, resupinate or effuso-reflexed, cap <2cm. Also found under toothed fungi.
Lastly the pore surface is not made up of round pores, but elongated or maze-like slots. In some cases, like Antrodia growing on a vertical surface, you might be able to picture how the pores get elongated and odd compared to the more typical pore crust that grows horizontally on the under surface of a log.
Trametes gibbosa - white, thick, up to 12cm across or more. May have prominent umbo at point of attachment. Susceptible to algae.
Coriolopsis (Trametes) trogii -
browner cap w/
Other Trametes have normal
Other Trametes have normal pores.
Datronia mollis - blackish cap, brownish, elongated slot pores. <7cm, effuso-reflexed. Hardwoods.
Other D. species have normal pores.
Coriolopsis gallica - brown fuzzy cap, large odd brownish pores and brownish flesh, on Cottonwood. Flesh black in KOH.
Schizopora paradoxa is especially variable, with ragged teeth (previous section) or maze-like (here). Usually hardwoods.
S. flavipora - orange-yellow tones. Hymenochaetales.
Abortiporus biennis - with shingled, zoned, white to brown furry caps, or misshapen aborted bodies with odd maze-shaped pores that blush red when touched. <20cm on hardwoods. Often stemless.
Porodaedalea pini - dark fleshed bracket in Hymenochaetales. >10cm
Also consider P. chrysoloma. Both turn black in KOH.
|Gloeoporus (Meruliopsis) taxicola - an orange to purple resupinate, may have only partially developed pores, but otherwise has a wrinkled surface like a crust.|
Soft Polypores - these are not hard like wood, but soft enough to tear a piece off of. Typically, they are the ones that don't have the extra hyphae types, but only the monomitic generative hyphae (but not always). Many of these may have odd pores as well. Tyromyces and Oligoporus (synonym: Postia) are said to feel "cheesy". Somewhat soft dark fleshed polypores can be found under Inonotus.
Tyromyces chioneus - white cheese, <10cm, fragrant, mild, hardwoods.
O. guttulatus - white, bitter, circular depressions on cap?
O. stipticus - bitter, black dots on cap? Both <10cm
Oligoporus ptychogaster - orange fuzz but more spherical, found partially buried underground or on wood, like a small Climacocystis.
Climacocystis borealis - large orange fuzzy species, on wood, <15cm, very closely related to Oligoporus
Oligoporus caesius - turns blue when handled or in age. <5cm. Pale blue spore print!
O. perdelicatus - does not turn blue, smaller than Tyromyces chioneus.
Amylocystis lapponica - <15cm, reddish brown initially turning even more brown, bristly cap, flesh black in iodine
O. leucospongia - ragged pores, curbed overhanging margin, <10cm. Spring at high elevations. Softer than Piptoporus.
Osteina (Oligoporus) obducta - confluent caps like Albatrellus confluens but on wood, dries bone hard. Stemmed. <12cm
Fistulina hepatica - "beefsteak", flesh exudes red juice, pores may be like individual straws, hardwood. In the Agaricales.
Laetiporus conifericola - sulphur shelf, orange yellow, applanate, conifers.
L. gilbertsonii - on hardwood
Now that the distinctive groups have been dealt with, I will show the rest of the polypores by stature type: Brackets (big and small), effuso-reflexed and resupinate. It is common to find an unusual form or size of one of these conks, so you may have to check more than one category. Since all of these terms describe how the mushroom sticks out from the wood, every single species from now on is saprophytic growing on wood. (Some may be parasitic).
Big Brackets - usually growing >10cm across as well as >1cm thick. Hard and woody, sticking straight out of the wood. Unlike most everything mentioned so far, these are mostly perennial, accounting for their abundance and size. Sawing one open can reveal "pore rings", much like tree rings.
1. Pale flesh and pores. (a) not entirely orange and not artist conks
Fomitopsis etc. - Fomitopsis 'pinicola' is probably the most commonly spotted fungus in the entire PNW. It just might be in every dead conifer tree in the region. If you see one (or almost any fruiting polypore) it probably means the tree is already dead. This group is recognized by pale pores and usually pale flesh inside (although you'll need a saw to cut one open). These usually turn reddish in KOH.
F. 'pinicola' - white pores and blunt rim, orange band that melts with a lighter, then blackish. Compare Heterobasidion.
F. ochracea - some specimens without a red band and with yellower pores are this. The outer cap chars with a lighter.
Young F. 'pinicola' is a white hemisphere and first develops orange tones. The oldest parts of this perennial are black. Lick the dewdrops, they're tangy.
Rhodofomes cajanderi - applanate, black cap, pink pores!
Rhodofomes rosea - hoof shaped (as tall as wide), pink pored.
Fomes fomentarius - pale hoof, bitter on hardwoods. Flesh and old pores are darker than the others. Phellinus have darker caps.
Piptoporus betulinus - hoof, curbed margin on birch, harder than Oligoporus leucospongia
Haploporus odorus - tan conk with strong anise odor, on willow, northern species.
Bjerkandera fumosa - like B. adusta but more bracket-like. Russulales.
Heterobasidion occidentale ('annosum') - dark brown cap, sharp margin (unlike Fomitopsis pinicola), orange tint to pores at certain angles. Specimens on hardwood, Incense cedar and pine may be a different species, H. irregulare. Related to the Russulales.
Often growing close to the ground, with a roughened cap surface.
Bridgeoporus nobilissimus - huge (>1m!) shaggy carpet cap pale, often with algae, noble fir. Until recently, only 9 known sites - 4 in WA, 5 in OR. Related to the dark fleshed Hymenochaetales.Don't disturb.
Oxyporus populinus - rows of pale brackets in a large mass, covered in algae.
1(b) Artist conks.
G. applanatum - applanate, cap sometimes covered in cinnamon spores.
G. brownii - taller, only on hardwoods with a yellow tinge to the pore surface.
Consider Ischnoderma resinosum too.
Ischnoderma resinosum - dark, velvety when young, zoned and wrinkled cap maybe with resin drops. Artist pores. Applanate. Black in KOH. Compare Ganoderma
1(c) Bright orange
Pycnoporellus fulgens - a beautiful bright orange fresh cap with paler pores. Turns reddish in KOH.
Other P. species are resupinate.
2. Dark flesh and pores. (a) Perennial
Dark flesh (and pores) - the pores may start out pale but the flesh inside is dark (cut it open). Remember, dark pores might have started out white if you have an artist conk. The colour of the flesh is more reliable than the colour of the pores.
Phellinus s.l. - perennial dark brackets sometimes with artist pores that turn even darker when touched. Related species can also be found effuso-reflexed and resupinate. These (and Inonotus) often have setae in the pores, microscopic dark cystidia that can be seen under low power. Flesh turns black in KOH.
Porodaedalea pini - rusty cap and flesh on conifers, often maze-like (called "daedalioid") pores. I once wondered out loud if Porodaedalea might have pores that were daedaleoid. If you learn a little Latin, some of these mushrooms just name themselves which I suppose is the point.
Phellinus igniarius - rusty flesh on hardwoods, artist pores
P. tremulae - on aspen, angled up at 45 degrees
Fomes - hoof, in the pale section, but sometimes with dark flesh.
Echinodontium - dark teeth underneath, bright red-orange inside, found on the tooth page.
Inonotus - annual dark brackets (pores not in layers) almost always with artist pores that turn even darker when touched. They are monomitic, meaning they are somewhat soft when fresh, although not usually as soft as the mushrooms in the soft section. They turn black in KOH. These (along with Phellinus) are in a different order, the Hymenochaetales, often having setae in the pores, microscopic dark cystidia that can be seen under low power. They are very difficult to tell apart. Some rare Inonotus are fully resuptinate.
I. hispidus - hairy, rusty cap?
I. cuticularis - mustard colours on margin?
Mensularia radiata - grows in clusters of smaller fruitbodies ~5cm. All with artist pores, all on hardwoods.
Onnia triquetra ('leporina') ('circinata') - sometimes stemmed, usually on pine trunks. Cap perhaps more radial than concentric. Up to 15cm wide or more.
Pseudoinonotus dryadeus - huge (<40cm), pale exterior, brown interior, at the base of fir or oak, red resin drops often on cap, with artist pores.
Inonotus obliquus - "chaga", on hardwoods, not really identifiable as a polypore, it looks like a crust in its asexual stage, which it is usually found in.
Phaeolus schweinitzii - rosettes, on the ground near wood, also found in the stemmed and odd pored sections. Yellow-green pores turn brown in age or when handled. Black in KOH.
Small Brackets - <10cm across or <1cm thick. They are almost always annual. This category is most confused with the effuso-reflexed fungi. If a fungus is usually mostly projecting from the wood, it will be found here. If most of the fungus is resupinate on the wood, it will be found under effuso-reflexed. The mushrooms don't always cooperate and a normally effuso-reflexed species might grow like a small bracket and vice versa. You may need to try both categories.
Trametes - "Turkey tails". The classic small bracket fungi, found on hardwoods. Some species grow quite large or thick and can be confused with the big brackets. Usually thin like leather (sometimes thick) with white pores, and most species are susceptible to getting tinted green with algae. Make sure there are pores underneath the cap, there are false turkey tails with nothing under the cap found on the crusts page.
T. versicolor - comes in many colours but always highly contrasting light and dark concentric circles. Pubescent.
T. hirsuta - zoned but not highly contrasting. Pubescent. Possible anise odor. Black line between 2 layers of flesh. Gets quite large!
T. ochracea - low contrast zones like T. hirsuta, but usually less hairy and not as thick. No black line.
T. pubescens - whitish when fresh, no coloured zones.
T. suaveolens - white, strong anise odor, bigger pores. More applanate than Haploporus.
Trichaptum abietinum - purple young pores turn brown, algae? on white cap, <4cm. Bracket or effuso-reflexed. Pores sometimes slightly odd. Conifers.
T. biforme - on hardwood, may have odd pores.
T. laricinum - gilled. Conifers.
Hymenochaetales, with Phellinus.
Bjerkandera adusta - caramel cap when young, grey artist pores, bracket or effuso-reflexed.
- larger, more bracket like. Pale grey pores, anise odor, dark
In the Russulales.
In the Russulales.
Gloeophyllum protractum - thick and wooden, brown flesh. G. sepiarium is gilled. May be perennial!
G. odoratum - odor of anise.
Coriolopsis gallica - Trametes-like or thicker with a brown fuzzy cap, large odd brownish pores and brownish flesh, on Cottonwood. Flesh black in KOH.
Phylloporia ribis - small bracket on Ribes (currant and gooseberries)
Normally large brackets that might be small:
Pycnoporellus fulgens - orange
Cryptoporus volvatus - found in gastroid, spherical with a pore surface inside. Counts on insects burrowing into it to spread the spores, otherwise it would go extinct. Brave.
Effuso-Reflexed - a portion of the mushroom lies flat on the wood, and another portion peels away from the wood exposing a cap. Most are annual. If more of the polypore is flat on the wood than sticking out, try here first, otherwise try the bracket section.
Trichaptum abietinum - purple young pores turn brown, algae? on white cap, <4cm. Bracket or effuso-reflexed. Pores sometimes slightly odd. Conifers. Hymenochaetales.
Bjerkandera adusta - caramel cap when young, grey artist pores, bracket or effuso-reflexed. Russulales.
'Antrodia' serialis - whitish "caps" bend away from a pore surface (~3/mm) on conifers. More easily detached than other 'Antrodias'.
'A'. albida - on hardwoods, also ~3 pores per mm, sometimes oddly shaped.
'Antrodia' malicola - similar, usually discoloured, pores sometimes oddly shaped. Hardwoods.
Amyloporia xantha - yellowish, small normal pores ~6/mm.
'A'. variiformis - brownish like 'A'. malicola, with the larger pores.
Oxyporus cuneatus - similar to Antrodia, pale, small (~3/mm) ordinary pores, often on barked Red cedar. (Hymenochaetales).
Antrodiella semisupina - white to yellow-brown, semi-translucent, velvety cap when young, usually on hardwood.
Skeletocutis nivea - similar, not translucent, usually darker brown cap.
Porodaedalea chrysoloma - conifers, thin, golden "Phellinus" with maze-like pores.
Fuscoporia viticola - more rusty than golden, more regular pores.
Phellinus conchatus - hardwood, numerous caps poking out of a resupinate mass. (These are perennials and turn black in KOH).
Gelatoporus (Gloeoporus) dichrous - white cap with pink gelatinous pores on hardwood. (Also found in soft category).
Skeletocutis amorpha - whitish with orange gelatinous pores and lower flesh on conifer wood.
|Gelatinous, coloured pore surfaces:
Skeletocutis amorpha and Gelatoporus dichrous.
Odd looking pore shapes are found in Schizopora and Irpex. Also 'Antrodia' and Pycnoporellus (see below)
Gloeoporus (Meruliopsis) taxicola - an orange to purple resupinate, may have only partially developed pores, but otherwise has a wrinkled surface
Staining colour when touched:
Ceriporia purpurea - white, turns purple where touched.
C. excelsa - turning pink
Other species don't stain
Colourful pore crusts, but not changing colour, nor dark rusty brown:
Pycnoporellus alboluteus - beautiful shades of orange, large, irregular tall pores. Spring. Turns red in KOH.
Ceriporia tarda - pinkish purple tones
C. viridans - faintly greenish pink
Gelatoporia (Ceriporiopsis) pannocincta - olive green
|Rigidoporus crocatus, Oligoporus placenta,
Hapalopilus salmonicolor and Gloeoporus (Meruliopsis) taxicola and some
Auriporia aurea, Anomoloma/Anomoporia
and 'Antrodia' xantha/
Byssoporia terrestris is usually yellow-orange, but may also stain various colours and is found on debris on the ground, with a fringed edge.
Dark rusty brown pore crusts (Phellinus s.l.) in the other polypore order, Hymenochaetales, mostly with dark, special microscopic cystidia called setae. These are perennial, and very difficult to tell apart. They all turn black in KOH.
Fomitiporia punctata - the species without setae
Phellopilus nigrolimitatus - dark rimmed crust?
Phellinus laevigatus (betulinus) - nondescript, usually on birch.
Fuscoporia ferruginosa/ferrea - sometimes brighter than others
Phellinidium ferrugineofuscum - sometimes purplish-brown
|The brackets Fomitiporia tsugina, F. robusta and Phellinus pomaceus rarely appear like very thick resupinates.|
I am out of distinctive characters. The rest of these are mostly pale resupinate pore surfaces, only trumped in obscurity by the pale resupinate crusts that don't even have a pore surface. These are mostly very difficult to ID.
'Antrodia' carbonica - amyloid flesh (turns black in iodine) (shown).
A. sitchensis - red/
A. sinuosa - usually odd sinuous pores, similar to Schizopora but bitter.
Trechispora mollusca - cottony with a wispy margin
Porothelium fimbriatum - pores separate like Fistulina instead of sharing walls between them.
|Other pale resupinates difficult to tell apart
without a microscope:
Antrodia, Antrodiella, Ceriporia, Ceriporiopsis, Cinereomyces, Diplomitoporus, Junghuhnia, Oxyporus, Physisporinus, Wolfiporia, Sidera, Dichomitus, Elmerina, etc.
There is nothing local with colour photographs, but the most important works from Europe, which contains many of the same species, are Fungi Europaei Volume 10 Polyporaceae s.l. by Bernicchia, in Latin and Italian with summaries in English and almost 275 species with colour photos and drawings of microscopic features, and the already mentioned Fungi of Switzerland Volume 2 available as an option entirely in English. Even without photographs, the 2 volume North American Polypores by Gilbertson and Ryvarden is a valuable reference.