Identify and appreciate mushrooms with spore prints

By Gary Raham
Nature Writer and Illustrator

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Mushrooms and toadstools seem to pop from the ground like rabbits from a magician's hat. After a bit of rain, or overzealous watering, they may appear suddenly in your lawn, rising over grass stems like precocious, pale weeds.

Before you mow them into oblivion, however, you may want to take a closer look at these representatives of Kingdom Fungi. In a mushroom's frenzy to reproduce while soils are moist, they produce a blizzard of spores whose collective beauty you can capture as a spore print.

A mushroom's rapid appearance after rain is no fluke. Although it takes five days under ideal conditions for an adult mushroom to sprout from a spore, most of a mushroom's growth occurs during the last six to nine hours.

Literally overnight, cells in the mushroom's stipe (stem) enlarge and elongate by hijacking a little soil moisture. The stipe swells into a cap on its tip that will expand like an opened umbrella. Beneath the cap, tissue-thin gills radiate from where stipe meets cap.

Each side of each blade-like gill supports phalanxes of spore-bearing cells, called basidia, separated by sterile spacer cells. Basidia launch their spores into "intergiller space" so that they will drift earthward and intercept air currents that will waft them to fertile soils.

Spores, being microscopic, would carry out their reproductive chores completely without attention if it weren't for the fact that fungi operate under the "more is essential" mandate. The common ink cap fungus, for example, which might sprout on fido's doo doo as well as the lawn, can produce as many as 5,240,000,000 spores in 48 hours, or 1,600,000 spores per minute. With that fecundity, even microscopic objects can become visible.

Because mushrooms often grow in clusters, a careful observer may even see telltale "spore dust" that has drifted from one mushroom cap to that of a shorter comrade beneath it.

By creating spore prints, a fungiphile can see the pattern of spores more clearly and have a much better shot at identifying a mushroom. Proper identification will not only satisfy mushroom hunters' curiosity, but will also prevent them from eating a poisonous sautéed toadstool.

Making spore prints

You will need a knife, paper (or thin piece of glass) and a bowl to make spore prints. Both the paper and the bowl should be bigger than the mushroom cap specimens. A can of spray mount (used by artists to stick paper to board) or an artist's spray varnish will make the prints permanent. Make the prints as follows:

1. Find a mushroom that looks firm and not dried out. The dark gills should also be visible beneath the cap. (Very young mushroom caps may have a veil of tissue covering the gills before the spores become mature.) Although many mushrooms produce dark spores, some produce spores that are white, pink or ivory-colored. Identification guides will often note spore color.
2. If your mushroom has dark gills, select a light colored paper on which to make a print. If the gills appear pinkish or white, select a dark-colored paper. As an alternative, some people make spore prints on a thin piece of glass (like the glass slides used under a microscope). That way, dark spores can be placed against a light background and vice versa.
3. With a razor blade or sharp knife, cut off the cap of the mushroom close to its base and place the mushroom gill side down on the paper or glass.
4. Cover the mushroom with a small bowl to block any air currents.
5. Wait several hours or overnight to be sure you get enough "sporefall." At the end of that time you should have a beautiful image created by millions of spores. The image will have rays of colored spores separated by radial no-spore zones directly beneath the sterile edges of the gills.
6. Preserve the image by spraying puffs of spray mount or varnish over the prints and letting the sticky cloud drift down so as not to scatter or smear the spores.

Spores like snowflakes

To see the spores as they fall, you will need a clear glass jar, a square of cardboard large enough to cover the lid of the jar, a straight pin and a flashlight.

1. Select a suitable mushroom as before and remove its cap.
2. Pin the cap of the mushroom so that the gills face away from the cardboard.
3. Place the cardboard over the jar so that the cap hangs gill-side down into the glass.
4. Turn off the lights and shine your flashlight through the glass. The falling spores will glitter like snowflakes on a still winter night.

Whether you make art out of multiple, overlapping spore prints, merely satisfy your naturalist's curiosity, or use spore prints to identify mushrooms for gastronomic masterpieces, you will never drive your lawnmower over a mushroom again without a twinge of regret.