The Carlisle Mosquito Online

Friday, October 14, 2005


Identifying mushrooms

The mushroom walk at the Towle Land planned for last Saturday was cancelled because of the rain but there are lots of mushrooms now. Here are some of the things to look at to help you identify cap-and-stem mushrooms.

This Agaricus mushroom illustrates very densely packed gills, gills free of the stem and ring around the stem
The cap: Take note of the color, the size, the shape and the texture. Some mushroom caps are vase-shaped, some are bell-shaped, some are flat like plates, some have a little knob called an umbo in the center. If it were a large knob, it would be a jumbo umbo. Some caps are sticky like last week's Sharp Scaly Pholiota, some are covered with warts, others are smooth and dry.

Under the cap: The spore-bearing surface of a mushroom is usually on the underside of the cap and its characteristics are often necessary for identification. Most often you will find either gills radiating out from the stem or a sponge-like surface which is the open end of thousands of tubes. In both cases, the color is important; it is often different from the color on the top of the cap. Some mushrooms have teeth or spines on the underside. One of these is a delicious edible called the hedgehog mushroom that I often find in the Towle Woods.

This Hedgehog mushroom or Hydnum reandum, shows spines on the underside.

Gills: For mushrooms with gills, look at the spacing (are the gills crowded or distant), look at how the gills attach to the stem (some will stop short of the stem, others will attach straight on, and others will blend with the stem and run part way down it. Some gills will be forked, some will have smooth edges and others serrated edges, and some will ooze juice when you break them.

Tubes: For mushrooms with tubes, look at the size and shape of the pores. The pores might be round or angular; they might be spread randomly or arranged in a radial pattern, and the pore surface might change color when bruised.

This Lactarius hygrophoroides illustrates well-spaced gills and gills that ooze fluid when cut or broken.

The stem: The stem is also important for identification, especially so for the deadly Amanitas. Use a knife or a small trowel to get as much of the base of the stem as possible. Amanitas have a bulbous base or a sac-like container from which the stem emerges. Some mushrooms have very long rooting stems. Also, look for a ring around the stem and note the general texture. Some stems have scales, some are speckled, some are smooth, and others look like they are covered with fine netting.

Spore color: Mushroom spores can be grouped into four categories for identification purposes: white or very pale, various shades of brown including yellow browns and rusty colors, very dark or black, and pink. Knowing the color of the spores will narrow the identification.

This Old Man of the Woods, Stobilomyces floccopus, shows large angular pores and a heavily textured cap.

Mushroom Field Guides: George Barron, Mushrooms of Northeast North America; Roger Phillips, Mushrooms and Other Fungi of North America (there is just now a new edition after having been out of print for many years); Gary Lincoff, Audubon Field Guide to Mushrooms of North America.

This is only the beginning. Other factors like habitat and seasonality also play a role. Most importantly, do not rely on the photos in a mushroom field guide when making an identification. There can be a huge amount of variation in any given species and a single photo cannot possibly be representative. The Boston Mycological Club has lots of walks and programs for people interested in learning about mushrooms. You can find it at
This Amanita species shows the sac-like base of the stem. This Xerula furfuracea shows an extremely long smooth stem with no ring and a large amount of stem below the surface of the ground.

2005 The Carlisle Mosquito