You judge gill attachment where a mature gill meets the stem. Free gills stop short and adnexed gills attach narrowly. Adnate gills attach broadly, notched gills narrow abruptly before they meet the stem, and decurrent gills run down it.
Mushroom gill attachment describes the inner edge of a true gill where it approaches or meets the stem. You read it from the side, ideally in a clean radial section, because the broad face of the gill hides the junction. Confirm that the gills are true gills, expose one intact junction, name the contact, then compare another stage. Attachment is geometry, and it tells you nothing about whether a mushroom is edible.
Prepare a Gill Junction You Can Actually Read
True gills are vertical plates where the mushroom produces its spores, each with two faces and a distinct edge. They radiate beneath the cap, and many caps also carry shorter plates that start at the margin and stop before the stem. Trace one full-length plate from the cap margin toward the stem before you judge its inner end. Short gills end on their own between margin and stem, so their endpoint cannot show attachment.
Chanterelle-like false gills are blunt ridges formed from the fruit body's flesh. They can fork and cross-connect, yet they never separate into the thin, blade-like plates of true gills. Pores and teeth sit outside the gill vocabulary too. Pores are the mouths of tubes and teeth hang as single spines, so forcing either surface into gill terms throws away the features that make it useful.
Note
Do not apply free, adnate, or decurrent to pores, teeth, folds, wrinkles, or an enclosed spore mass. First choose the correct fertile-surface branch, then use attachment terms only for true gills.
Look at a fresh area of the underside. Insects and decay can eat away the inner gill ends and leave a false gap around the stem that looks like free attachment.
How to Expose the Gill-Stem Junction
Pick a mature but firm specimen whose cap has opened enough to show the underside. Very young caps squash the junction together, and old caps can pull or tear the gills away from the stem. Before you start, make sure the cut face will keep both the cap radius and the intact inner gill edge.
Do not slice parallel to the gills. That cut shows the broad faces of the tissue and can remove the edge profile that tells a notch from a narrow attachment. Use a clean blade on firm tissue. Soft old flesh squashes under the knife, and a sawing motion tears the few millimeters where adnexed, adnate, and notched attachments differ.
You can also bend the cap gently or remove one wedge to open a crowded underside, but stop before the gill tears from the stem. Cutting cleanly keeps the natural junction more faithfully than pulling tissue apart does. Take a close side photo with the stem vertical and the cap profile in view. Extreme camera angles can shrink a broad attachment into a thin line or hide a real gap.
Around the Home and GardenMushrooms Growing in a Lawn: Patterns, ID and Pet RiskWhat Are the Six Gill Attachment Types?
The main attachment terms describe a continuum, running from no contact at all to a long descent down the stem. Where your specimen falls between two terms, a qualified phrase records it better than forced precision. The six terms run from no contact to descent, and each one names the junction itself, whatever direction the rest of the gill takes.
| Type | Contact with stem | Side-profile cue | Closest confusion |
|---|---|---|---|
| Free | No contact | Gill ends before the stem and leaves a channel | Seceding gills that detached with age |
| Adnexed | Narrow contact | Gill tapers before touching a small part of the stem | Nearly free or narrowly adnate |
| Adnate | Broad contact | Much of the gill depth meets the stem directly | Slightly decurrent when the cap angle slopes |
| Notched or sinuate | Attached after an indentation | Gill narrows abruptly or curves upward before contact | Adnexed when the notch is shallow |
| Subdecurrent | Descends a short distance | Inner edge continues just below the cap-stem junction | Adnate on a sloping cap |
| Decurrent | Descends clearly | Gill tissue runs down the stem for a visible distance | Blunt false gills or folds |
Free is the only main term that means no attachment. Its narrow, clear channel should run all the way around the stem, and a gap that shows up only where a damaged gill has pulled away does not count. Adnate gills run straight into the stem with broad contact, while adnexed gills are only just attached at a narrow point. What you are measuring is how much of the gill's depth joins the stem, and how crowded the gills are has no bearing on it.
Notched attachment needs an abrupt inward curve right before contact. Record a smooth, gradual narrowing as adnexed, and leave a groove made by damage unclassified. Guides use notched, emarginate, and sinuate in different ways, so write the visible geometry in plain words beside your chosen term, for example "abrupt notch before narrow attachment."
Decurrent gills stay gill tissue as they run down the stem, and the length of that run varies. Subdecurrent covers a short run that goes beyond a direct attachment but stops short of a sustained descent.
Free, Narrowly Attached, or Broadly Attached
These three categories cause the most uncertainty, because the difference between them spans only a few millimeters. Judge them by the channel between cap and stem and by how deep the actual tissue contact goes. The apparent direction of the whole gill will mislead you here.
- Free
- Confirm a real space between gill and stem on several intact plates
- Adnexed
- Follow the gill as it tapers to a narrow point of contact
- Adnate
- Look for a broad inner edge joined through much of its depth
Remote is a handy qualifier when free gills stop an obvious distance from the stem. It describes the width of the gap and does not name a separate mechanism. Use subadnexed or subdecurrent only when your key or reference uses that in-between term consistently. In ordinary field notes, a measured phrase such as narrowly attached or running 2 mm down the stem often keeps the observation clearer.
Mycologists call gills seceding when they touched the stem in youth and pulled away later. Look for torn tissue, a line on the stem, or younger specimens that still show the original contact. Compare several plates around the cap, and do not decide from one chewed or split gill, since local damage and uneven growth can change a single junction.
Cap angle misleads as well. On a strongly domed cap, a broadly attached gill may reach the stem on a slope, and it stays adnate unless tissue continues downward below the junction.
How Does Age Change Gill Attachment, and How Far Can You Trust It?
As the cap expands, the angle between cap, gills, and stem changes. Young caps squash the junction, which becomes easier to see at maturity and can then distort again as the cap turns up or dries. The inner gill edge can stretch, curve, or become more exposed as the cap widens. That shift can make a narrowly attached gill look notched even when no abrupt indentation showed earlier.
Some attached gills separate with age. Mature or old specimens can therefore look free, while a leftover line on the stem or a younger cap shows that the gills were seceding. Compare that line and the cap angle before you call the older junction free.
Drying can also shrink gill tissue away from the stem after collection, especially in thin caps. Record the fresh junction before transport, and treat any later gap as a changed condition that leaves your original term standing. Old gills also sag, tear, darken under spores, and lose their crisp edges to insects. Note the condition before you apply a precise term.
When fruit bodies are plentiful, take two or three stages of growth from the same patch. Keep substrate, growth pattern, cap surface, spore color, and the other features in view so you know the stages really belong together. If you have only one unclear old specimen, write "apparently free, possible seceding attachment." That phrase keeps more information than a confident label your evidence cannot support.
Use Attachment as One Character
Gill attachment can knock candidates out of a field key, especially when the choices split between free and clearly decurrent gills. It carries less weight when closely related species range from adnexed to adnate, or when the junction changes with maturity. Write the term with its stage and your confidence, such as mature, broadly adnate, high confidence, or old, apparently free, possible secession. That way the note keeps both the observation and its limit, and a borderline junction does not turn into false precision.
Record gill spacing on its own as crowded, close, subdistant, or distant when your guide uses those terms. Spacing describes the gaps between plates, and attachment describes their inner ends. Add gill thickness, edge shape, tiers of short gills, color, bruising, latex, and changes as spores mature. Pale young undersides can darken dramatically while the attachment stays exactly the same.
Then check the attachment against the cap profile and surface, the complete stem base, any ring or cortina, veil remnants, flesh reactions, spore deposit, substrate, nearby trees, region, and season. Do not take an attachment type from a species name in an app and then reread the specimen to fit it. Describe the junction before you open any candidate pages, so your observation stays your own.
If blunt ridges run down the stem, record them as false gills or folds, and do not call them decurrent true gills. That structural difference can outweigh the downward direction both share.
No attachment type makes a wild mushroom safe to eat. Finish at the narrowest name your whole record supports, and get a qualified local review whenever the identification feeds into a decision to eat.
