Panaeolus subbalteatus (know as subbs by some people) is by far the most widely distributed psychoactive mushroom in the United States (if not the world). Although this mushroom is typically ranked as "weakly potent" to "moderately potent," it's all that some people will be able to find. This guide contains a very large amount of pictures of Panaeolus subbalteatus and it's most common, inactive, look-a-like Panaeolina foenisecii.

First I will start off by explaining the best places and times of year to find these mushrooms.

Habitat.
P. subbalteatus grow in many natural environments. The places that it is most commonly found is growing from horse manure, stable shaving compost (horse manure and woodchips), hay, and grass compost piles. These mushrooms are RARELY found growing in very well fertilized lawns and on cow manure... so don't waste much time looking in those areas. These mushrooms will only grow from the substrates previously mentioned; they will never grow on wood.

Season and when to hunt.
Here in Georgia, Panaeolus subbalteatus start popping up in late February or early March. They tend to show up about a month after the last frost. They start fruiting when the temperatures drops no lower than 50ºF at night time. They will continue fruiting from the last frost until about the first freeze. In order to find P. subbalteatus (or any mushroom for that matter) a fair amount of moisture is needed. The best time to look for these mushrooms is after a day or two of heavy rain, depending on temperatures. The higher the temperatures, the faster things will dry out. Time of day doesn't matter, mushrooms don't suddenly disappear back into the ground when the sun pops up. If you live in an area that isn't prone to getting a lot of rain (ie: Southern California), try checking large grass or compost piles as these tend to hold moisture a lot better than just plain ol' horse dung would.

Look-a-likes / Description
These mushrooms tend to be a bit difficult to identify because there are many member of the Panaeolus and Panaeolina genera which look very similar to them. There are several members of the Panaeolus family that will fit the description of P. subbalteatus but that will not be included here.
The most common look-a-like for P. subbalteatus would definitely be Panaeolina foenisecii. There are a few ways that you can differentiate these mushrooms:

• The easiest being the stem. Panaeolus subbalteatus tend to have thick, beefy stems compared to P. foenisecii . The stems of P. subbalteatus also tend to be dark, almost a dark brownish red color, while most foenisecii have white stems. The stems of subbs also have a wavy fibrous appearance, where as with foens, the striations tend to be almost completely stright.
• Another unique feature about P. subbalteatus is it's gill structure. At full maturity, subbs will have very dark, almost black gills. Sometimes these gills will have a white or grey fringe on them. Foenisecii tend to have brown gills. The gills on P subbalteatus are also very closely packed, while foens gills tend to be more wide spread. One phenomenon that LizardKing and I (Gumby) have noticed is that the gills on foenisecii hang lower than the margin (edge) of the cap Panaeolus subbalteatus gills rarely grow below the margin (see pictures below).
• The caps of the mushrooms are another good indicator as well. Panaeolus subbalteatus tend to grow all kinds of funky deformed caps (not perfectly round). At full maturity they often become wavy, somewhat like Psilocybe cyanescens. Differentiating P. subbalteatus from P. foenisecii is pretty much impossible, their color characteristics are the same. Once these mushrooms have been in the sun for a while the caps will bleach to an off white tan/cream color.
• Habitat also sets these mushrooms apart. Foens will grow mainly in lawns where as subbs tend to stick to horse manure, hay, or composted grass.
• P. Subbalteatus tend to grow in tight clusters while P. foenisecii are loners.
• The last reliable feature to separate these two mushrooms is their spore prints. Panaeolus subbalteatus drops JET BLACK spore prints where as Panaeolina foenisecii drops very dark brown spore prints.
• There is one other way to check to make sure you have the right mushrooms. Try bruising the suspected mushrooms at the base of the stem where some mycelium is present if you see bluing on the mycelium, you could have an active. Bluing is not a common feature on subbs but it does happen. I've probably picked well over a thousand subbs and I've seen 3 of them bruise blue.

Here are some pictures to illustrate some of the things I just discussed:

Left to right these arrows point out the following (Photo credit: Gumby)
1. Wavy striated fibers on the stems, note the thickness of the stems
2. Bluing on the stem (rare).
3. Wavy/deformed margin (cap).

Subbalteatus with whitish fringes on the gills (Photo credit: Gumby)

Deformed caps and cluster growth of subbalteatus. (Photo credit: angryshroom)

Comparison of spore prints. (Photo credit: Gumby)

Panaeolina foenisecii- note the long, thin, and white stems. Also note how some of the gills hang lower than the margin. (Photo credit: Gumby)

Subbalteatus on the left, foenisecii on the right. Note how the gills on the foens are lower than the margin. (Photo credit: falseaddiction & Gumby)

 

Now that you've done your homework, you should take a chance to relax an look at some pictures:

Picture Galleries:

Panaeolus subbalteatus

Panaeolina foenisecii