Mushroom Gills vs Pores Identification Guide

Why the Underside Is the First Thing a Mycologist Looks At

When a mycologist receives an unidentified mushroom, they turn it over immediately. The underside of the cap — the hymenium — is the spore-producing surface, and it comes in four main forms. Each form immediately narrows the identification to a specific subset of genera. Gills (lamellae) are thin, blade-like plates radiating from the stem like spokes — this is the most common type and includes familiar species like button mushrooms, Amanitas, and chanterelles. Pores are tiny round holes on a sponge-like surface — found in boletes and polypores. Teeth (spines) are downward-hanging pointed structures — found in hedgehog mushrooms and lion's mane. False ridges (blunt, forking, wrinkle-like) are found in chanterelles. This initial classification eliminates hundreds of species from consideration before you look at colour, size, or habitat.

Understanding Gill Anatomy

Gills are not all the same, and their specific characteristics provide critical identification clues. Gill attachment — how the gills connect to the stem — is one of the most diagnostic features. Free gills do not touch the stem at all (Agaricus, Amanita, Lepiota). Adnate gills attach squarely to the stem (many Tricholoma). Decurrent gills run down the stem like an inverted funnel (oyster mushrooms, Clitocybe). Notched (sinuate) gills are attached but curve upward just before meeting the stem (Tricholoma, Entoloma). Gill spacing matters too: crowded gills (many thin blades packed tightly) versus distant gills (widely spaced with visible cap flesh between them). Gill colour often differs from cap colour and may change as spores mature — young Agaricus gills are pink, maturing to dark chocolate brown.

Pore Surfaces: Boletes and Polypores

Pore-bearing mushrooms fall into two major groups. Boletes are fleshy, stem-and-cap mushrooms that grow from soil (not wood) and have a spongy pore layer underneath that can usually be peeled away from the cap flesh. The king bolete (Boletus edulis, also called porcini or cep) is one of the world's finest edible mushrooms: brown cap, white pore surface when young (aging to yellowish-green), thick bulbous stem with fine white netting. The general bolete safety rule (with exceptions) is: avoid any bolete with red or orange pores, any that stain intensely blue on cutting, or any with a bitter taste. Polypores are bracket or shelf fungi growing on wood with a pore surface that is typically not separable from the flesh. Most polypores are tough and inedible but include important edibles like Chicken of the Woods and Hen of the Woods.

Teeth and Spines: The Hydnoid Fungi

Mushrooms with teeth (spines) hanging from the underside of the cap are among the easiest to identify because there are relatively few species in this group and no common toothed species are dangerously toxic. The Hedgehog Mushroom (Hydnum repandum) has a pale orange-tan cap with cream-coloured spines underneath, grows from soil in forests, and is edible with no dangerous look-alikes — the spines are unmistakable. Lion's Mane (Hericium erinaceus) has long, cascading white spines growing from a single point of attachment on dead hardwood. Its relatives (Bear's Head, Coral Tooth) have branching structures with shorter teeth — all are edible. The toothed hymenium immediately eliminates the possibility of confusion with gilled mushrooms, which contain many more dangerous species.

False Gills vs. True Gills: The Chanterelle Test

One of the most important distinctions in mushroom identification is between true gills and false gills. True gills are separate, blade-like structures that can be individually separated from the cap — they are thin, sharp-edged, and uniform in depth. False gills are blunt, shallow, forking ridges that are continuous with the cap surface — they look like wrinkles or veins rather than separate blades and cannot be cleanly peeled away. This distinction is critical for separating chanterelles (false gills, edible) from Jack O'Lanterns (true gills, toxic). Run your finger across the underside: true gills feel like distinct ridges with sharp edges; false gills feel like smooth, rolling bumps. With practice, the difference becomes immediately obvious.

How Gill and Pore Features Change With Age

Spore-bearing surfaces change significantly as a mushroom matures. Young Agaricus gills are pale pink, maturing through rose-pink to dark chocolate brown as spores develop — the colour of the gills on a mature specimen is very different from a young one. Bolete pores start white or pale and often age to yellowish, greenish, or olive as spores mature. Some boletes develop cracks or tears in the pore surface as the cap expands. Chanterelle false ridges become more prominent and forked as the cap expands. When describing gills or pores, always estimate the age of the specimen — is it young and fresh, mature, or past its prime? This context helps Dr. MycoTek interpret colour and spacing observations accurately.

Using Hymenium Type to Narrow Identification

The hymenium type immediately narrows your identification to a specific subset of genera. Gills: you are in the Agaricales or related orders — the largest group, containing both prized edibles and the most dangerous toxic species. Pores on a fleshy cap growing from soil: you have a bolete — most are edible, but some are toxic. Pores on a shelf growing on wood: polypore — most are too tough to eat. Teeth: hydnoid fungus — all common species are edible. Smooth or wrinkled undersides: may be a chanterelle relative, a club fungus, or a coral fungus. This initial classification eliminates hundreds of species before you even look at colour, size, or habitat.

Practical Tips for Examining the Underside

Examining the underside requires a bit of technique. For gilled mushrooms, look at the gill edge (smooth, jagged, or coloured differently from the gill face?), the gill spacing (how many gills per centimetre of cap margin), and attachment to the stem. Use a hand lens (10x magnification) if available — it reveals fine details like gill edge colour and pore size that are invisible to the naked eye. For boletes, gently press the pore surface with your finger and wait 30 seconds — many boletes stain blue on the pore surface when bruised, which is a key identification feature. For polypores, count the pores per millimetre — pore density varies significantly between species and is a reliable diagnostic feature.