Cap shape

Convex

A convex or hemispherical cap is the classic, most recognizable mushroom silhouette, the one drawn in children's books. It looks like an upside-down bowl, a dome or an open umbrella.

From an evolutionary point of view, this is the ideal architectural shape. As David Arora notes, a convex dome lets a mushroom:

1. Withstand physical load: Rain does not pool on such a cap; water runs off the margins perfectly.

2. Protect the hymenophore: The tubes or gills under the cap are well shielded from direct sunlight and raindrops.

3. Push through the soil easily: The hemispherical shape (during growth) works like a wedge that parts the leaves and earth.

24 species in the database.

Classic examples

About 70% of all forest mushrooms have exactly this convex shape at their best (mature but not old) stage:

1. The bolete family: Porcini, slippery jacks, aspen boletes, bay boletes. Their cap is always convex (like a burger bun), and only in deep old age can it become completely flat.

2. Amanitas (Amanita): The fly agaric, the panther cap and the death cap (in middle age) have beautiful, symmetrical convex caps.

3. Brittlegills (Russula): For brittlegills, the convex shape is a transition between the ball-shaped bud and the flat "saucer" of old age.

4. Tricholoma (knights): The violet knight, the streaked knight and the Poplar knight.

Questions and answers

Why is my porcini not convex, but has a flat cap with raised margins?

If a porcini has lost its classic dome and become flat, and its tube layer (the sponge) has turned green and very soft, the mushroom is very old. At this age the flesh goes loose, loses its turgor (firmness), and the cap flattens under its own weight. Picking old, completely flat porcini is not recommended because of the risk that putrefaction toxins have built up in them.

Sources

1.Зерова М.Я. та ін. Визначник грибів України. 1979
2.Roger Phillips. Mushrooms (Roger Phillips)
3.David Arora. Mushrooms Demystified
4.Index Fungorum