Hymenophore

What the hymenophore is and why it's needed

The hymenophore is the part of the mushroom's fruiting body that carries the hymenium (a microscopic layer of spore-producing cells). M.Ya. Zerova, in the “Key to the Fungi of Ukraine,” explains that the hymenophore's evolutionary task is to maximize the surface area for producing the millions of spores needed for reproduction. Instead of a flat surface, mushrooms have evolved complex three-dimensional structures — tubes, gills, spines or folds — that fit a gigantic number of spores into the minimal area under the cap.

David Arora, in “Mushrooms Demystified,” emphasizes that the macroscopic form of the hymenophore is the first "filter" in classifying macrofungi. Most field guides are built on exactly this principle: first you determine the hymenophore type, and only then do you look at color, smell or the presence of a volva.

Main morphological types of hymenophore

Roger Phillips, in his guide “Mushrooms,” and modern taxonomy distinguish several fundamental hymenophore types, which underlie the division of mushrooms into major groups:

1. Gilled (Lamellate): The hymenophore takes the form of radial gills running from the stem to the cap margin. This is the largest group of mushrooms (Agaricales), which includes brittlegills, Agaricus mushrooms, amanitas, honey fungus and most poisonous species.

2. Tubular or pored (Poroid/Tubular): The hymenophore consists of a mass of vertical tubes that look like a sponge with tiny pores from below. Typical of the Boletales — porcini, slippery jacks, brown birch boletes — and also of many bracket fungi.

3. Spiny or toothed (Hydnoid): The spore-bearing layer looks like soft or stiff needles, spines or teeth hanging downward (for example, in the wood hedgehog — Hydnum repandum).

4. Folded (Plicate/Ridged): The surface is covered with wrinkles, veins or blunt folds that resemble gills but are not true separate blades (typical of chanterelles — Cantharellus).

5. Smooth: The simplest form, where the hymenium covers an even or slightly wavy surface (for example, in coral fungi or Craterellus).

6. Chambered (Gleba): The spore-bearing layer is inside a closed fruiting body (for example, in puffballs, truffles or stinkhorns), where spores mature in internal chambers.

For a forager, determining the hymenophore type is a matter not just of curiosity but of safety. For example, among pored mushrooms in our latitudes there are no species capable of causing rapid fatal poisoning, whereas among gilled mushrooms there are dozens.