Mushroom Anatomy and Spore Prints

What a mushroom is

A mushroom is the fruiting body of a fungus. The fungus itself is a web of fine threads, the mycelium, living for years in soil, wood, or roots. It sends up mushrooms when conditions are right, mostly after rain, to release spores. That’s why a good spot produces year after year, and why picking mushrooms doesn’t harm the fungus.

Fungi live in three main ways, and knowing which tells you where to look:

• Mycorrhizal fungi partner with living tree roots, trading minerals for sugar. Chanterelles, destroying angels, and many boletes grow on the ground near particular trees, often oaks.
• Saprobic fungi decompose dead wood or leaves. Oyster mushrooms, most shelf fungi, and Galerina grow on dead wood.
• Parasitic fungi attack living trees, such as honey mushrooms and some chicken of the woods.

The parts

The features you’ll use again and again:

• Cap: shape, color, texture (smooth, scaly, sticky, warty), and whether it has patches left from a veil.
• Underside: gills (thin blades), pores (a spongy surface of tiny holes, as in boletes and polypores), teeth, or false gills (blunt, forked ridges, as in chanterelles).
• Gill attachment: free from the stem, attached, or decurrent (running down the stem, as in oysters) ¹.
• Stem: central, off-center, or absent; solid or hollow; smooth or scaly.
• Ring: a skirt on the stem, the remains of a veil that covered the young gills.
• Volva: a cup or sac at the base, the remains of a veil that enclosed the whole young mushroom. A white sac-like volva, often buried, together with a ring and free white gills, marks the deadly Amanitas ².

So dig up the whole base. Never cut a gilled mushroom off at the ground until you know what it is.

What to record

Note these in the field, before you open a book, so the book doesn’t talk you into a match ³:

• Substrate: soil, wood (dead or living, which tree), buried roots, moss, leaves.
• Nearby trees, especially for ground-growing species.
• Growth habit: alone, scattered, in clusters from a single base, or in shelves.
• Base, ring, and gill attachment.
• Smell: mealy, fruity, anise, radish.
• Changes: bruising colors, latex or juice when cut.

Photograph the top, the underside, the stem, the base, and a cross-section.

Making a spore print

A spore print is the color of the spores in mass, and it splits mushrooms into groups that look alike otherwise. To make one ³:

1. Cut off the stem and set the cap, gills or pores down, on paper or glass. For a big mushroom, slice off a piece of cap.
2. Use half white and half black paper, or glass, so both light and dark spores show.
3. Cover it with a cup or bowl to stop drafts and drying.
4. Wait several hours; overnight is surest.

Common results: white (Amanitas, oysters, honey mushrooms in a pale cream), pink to salmon (some chanterelles, Entoloma), rusty brown (Galerina, Cortinarius), chocolate brown to purple-brown (Agaricus, the meadow mushroom group), black (inky caps).

The print can be decisive. Galerina, which has killed people who mistook it for honey mushrooms, gives a rusty-brown print, while honey mushrooms give a white one ⁴.

Cooking and eating

• Cook all wild mushrooms. Several common edibles, morels included, cause illness raw.
• Eat a small amount the first time you try a species, and keep an uncooked sample in the fridge.
• Eat only fresh, firm specimens. Old, wet, or buggy mushrooms spoil and cause food poisoning that has nothing to do with the species.

What to take from this

A mushroom is the fruit of a long-lived fungus that grows with tree roots, on dead wood, or as a parasite. Learn the cap, underside, gill attachment, stem, ring, and volva, and dig up the whole base. Record substrate, trees, habit, smell, and changes before opening a book. Make spore prints on half-white, half-black paper; a rusty-brown print separates deadly Galerina from honey mushrooms. Cook every wild mushroom and try small amounts first.