Habitat

Where exactly is the fungus growing? On a tree, a log, the ground? What kind of tree? And what other trees are nearby? You won't find oak-loving fungi under pines, or vice-versa, and may be able to eliminate a large number of possible species at once.

Scent and Taste

Fungi often have a very distinctive smell, such as garlic, anise, rotting flesh, or even shellfish. The odour may only become apparent if you crush a piece of flesh. To taste, select only a very fresh specimen (fungi quickly lose their flavour), place a very small piece on the tip of your tongue, and spit it out immediately. Even poisonous fungi will not harm you as long as you don't swallow any portion.

Size

Field guides usually provide a range of cap size and stalk height in their species descriptions, and any other useful dimensions that are typical of a species. Remember that these are average ranges, and you may well find fungi that are larger or smaller.

Colour

Colour of cap, stalk, and gills is often the most obvious feature of a fungus. It can be helpful in identification, but don't be misled. Other characteristics are more important and less variable. Colour changes with the age of the individual and is affected by environmental conditions—sun and rain, for example, can both bleach a fungus's colours. Different forms within one species can have quite different colours. Morels even take on different colours when associated with different trees. Colour perception also depends to some extent on the eye of the beholder. So don't be surprised if your fungus is a different colour to the one in the book or on this website!

Spore colour is a much more reliable clue than cap or stalk colour. Gilled fungi can be separated into a number of groups depending on whether their spores are light, dark, brown, or pink. To be sure of spore colour you need to make a spore print. Cut or break the cap off and lay it gill or pore side down on a piece of white paper. You may soon be rewarded with a colourful smattering of spores. If not, take a specimen home and try again, leaving it overnight.

Staining of the tissues is useful in some groups like the boletes, which change colour when bruised. Also note the speed of the colour change.

Cap, Stalk, and Gills

Cap, stalk, and gills are extremely variable. Caps may be conical, cylindrical, umbrella-shaped, bell-shaped, convex, concave, flat-topped, funnel-shaped, knobbed, and so on. They may be smooth or warty. Some are sticky (viscid) when wet, others become slimy (glutinous).

Stalks may be straight-sided or taper up- or downward. Some have a club-shaped or even bulbous base. Many species have no stalk at all.

If gills are present, note how they are spaced, if they are attached to the stalk or not, the shape and position of the stalk, and the presence or absence of a partial veil, universal veil, annulus, or volva.

Texture

Texture can be important. Boletes are spongy, and bracket fungi are woody. Other species are leathery, corky, brittle, and so on.

Microscopic Features

If you have access to a microscope, you'll be able to examine features such as the size, shape, and surface ornamentation of spores, which all provide clues to fungus identity. Other microscopic features, like the orientation of hyphae in the gills are useful indicators too.

You can place spore dust from a spore print in a drop of water on a slide, and cover it with a coverslip. It's best to examine gill cells in cross section, by cutting a very thin slice with a razor blade.