Cap & gills
Cap shape, gill spacing, stem ring — the anatomy that names a species.
The anatomy that names it
Before you reach for an app, look at the mushroom itself. Cap shape, how the gills attach, whether there's a ring on the stem — these are the details that separate species.
The checklist
cap convex? flat? umbonate? wavy? gills free, attached, or running down the stem? ring a skirt on the stem, or none? base a bulb, a cup (volva), or plain?
Why it matters
Apps are good, but they guess. The mushroom in your hand never does. Learn to read it and you'll rarely need the phone.