ID Basics: Gills vs. Pores

So I thought I'd start a little ongoing series on identification basics and hints. Trying to ID by looking at photos online certainly doesn't compare to being out in the field but there are some easy techniques that you can still look at.

One of the first features I examine when finding mushrooms, even before color, shape, size, or habitat, is what is located on the underside of the "top" of the mushroom. The top could be the cap on a cap-and-stem mushroom, or the protruding "shelf" of a polypore.

GILLS

Okay, so you've turned over your mushroom (or you've taken out a telescoping mirror and have positioned it under the mushroom - - ummm... yes, I have been actually been known to do this to avoid picking it... let's move on, shall we?) and you see all these usually straight, line-like ridges, extending from the stem to the edge of the mushroom. Congratulations, you have found gills as shown in this Tricholomopsis. Picture the straight lines of fish gills.

Most mushroom field guides will further break down characteristics of gills. Are they decurrent? Adnate? Adnexed? Free? Are the distances between the gills equal? Forked? Radiating? We'll look at those characteristics at some point down the line.

PORES

So you're looking at your mushroom and you don't have gills. Instead you see what appears to be the surface of a sponge (like on this Bitter Bolete pictured). Some of these small "holes" may require a hand lens to see. Many mushrooms will have easily visible, larger holes. These are pores. Picture the pores of your own skin. In the case of mushrooms, the pores are the ends of tiny tubes that extend through the cap, not just a random smattering of holes on the surface. The vast majority of Boletes have these tubes/pores. Further characteristics of pores can be examined when identifying a mushroom, including the bruising of these pores (which can turn color, further helping to establish the species you have) but we'll get into this later.

If you can differentiate between gills and pores, you've made a great leap forward in ID'ing your mushroom. In both cases this is the part of the mushrooms where the reproductive spores are produced.

To complicate things just a bit, there are features other than gills and pores you might find, including gill-like veins, teeth/spikes, and a huge array of characteristics that are more common to mushrooms that are not cap-and-stem mushrooms or polypores, like stinkhorns, puffballs, sac fungi, etc. But gills and pores will be the major features on most of the mushrooms you find while out and about.

NEXT TIME: In the next ID Basics, we'll take a closer look at those outliers such as veins, teeth, spikes and a few others in ID Basics: Hep! It's not a gill or pore!