Foraging Guide: The Awesome Agarics

The Agaricus Genus

The Agaricus Genus of mushrooms can often be a challenge for foragers. On the one hand, they are very familiar to most of us, namely because we buy and eat them all the time from the supermarket, but they can also be notoriously hard to accurately identify down to species level because there are so many similarities between them.

All Agaricus species share some common traits. They are generally stout mushrooms, with wide, portly caps, that range in colour from white, to tan, to brown. Some have smooth caps, others have thick cracks or scales, and others still have very pretty concentric repeating patterns. The gills on the underside are crowded, do not extend down the stem, and often start-off very pale, almost white, turning pink, then brown, then almost black as they age due to their chocolate brown spores. Their stout stems always carry a skirt, a remnant of a partial veil that protects the gills and breaks away when the cap opens, although this is not always visible on the stem, as they are often very delicate and can wash away in wet weather.

Although some Agaricus mushrooms are mycorrhizal (i.e. they grow in association with certain types of tree), most of the commonly foraged varieties are considered to be grassland fungi, growing in pastures, fields and paddocks, such as Horse and Field Mushrooms. A few would also be considered woodland fungi, such as the Blushing Wood Mushroom and the beautiful Prince Mushroom.

The Genus contains many edible varieties, as well as some toxic ones, although none of these are deadly. This makes them a fairly safe edible, as long as the toxic species can be ruled out during identification.

Foraging for Agarics

Identifying Agaricus mushrooms down to species level can often be a bit daunting. With over three hundred known species, and all sharing very similar traits, many novice foragers simply decide to just admire them from afar. Agarics though, are one of the tastiest wild mushrooms, and luckily for us here in the UK, there are only a couple of them that are considered to be toxic. Ruling these out, therefore, can make the job of enjoying these mushrooms for dinner much, much easier! One thing I will say though, is having a keen sense of smell will stand you in good stead for foraging Agarics, so if you're nasally challenged, then take extra care!

Toxic Agarics

The two Agaricus mushrooms to really watch out for are the Yellow Stainer (Agaricus xanthodermus) and the Inky Mushroom (Agaricus moelleri). Both of these smell highly unpleasant, like cleaning chemicals (TCP), iodine, or Indian ink, especially during cooking, which is a key identifying feature. The Yellow stainer is white to off-white, often has a "boxy" or square appearance to the cap, and flushes bright chrome yellow when the cap is scratched or damaged, and also around the base of the stem when cut in half. The Inky Mushroom also stains yellow (although not nearly as vividly), which later fades to brown, but has concentric brown scales on the cap. In both cases, it is usually the strong acrid smell that sets them apart from other Agarics. You can test for both smell and yellow staining in the field by scratching the cap, taking a cross-section and having a good sniff, but a more reliable way involves placing a piece of the cap in the microwave for 10 seconds on a small square of kitchen roll. If the kitchen roll stains yellow and the air is filled with an awful chemical smell, then you can be fairly certain that you have gathered one of the toxic Agaricus species. Hard Luck! Conversely, if there's no yellow staining and no horrid smell, then you've found one of the edible species. Rejoice!

Perhaps I'm just lucky, but I've only ever found a couple of Yellow Stainers, and one Inky. This is the reason for a lack of photographs! They are quite distinctive, particularly the yellow stainer. The vivid chrome yellow is generally unmistakable, and once you've encountered it, it is fairly easy to see (if not smell) the difference. A quick google search will show you! next time I encounter one, I'll be sure to photograph it for the blog!

Common Edible Agarics

As already mentioned, the Agaricus genus includes some pretty delicious fungi. The following list contains seven of the more popular foraged varieties, alongside some key identifying features.

The Field Mushroom, Agaricus campestris

Field Mushrooms are a common sight in pastures, paddocks and, as the name suggests, fields. Looking like slimmer versions of supermarket mushrooms, they tend to be on the smaller side, with white to off-white caps and white flesh that often stains pink when damaged or bruised. Their gills start out pale, before turning pink, then brown, then black as they mature, and they often grow in rings. They are pleasant mushrooms to eat, with a mild mushroom flavour and a familiar mushroomy aroma. The pink staining makes them a relatively easy agaric to identify for the table. They tend to appear in June or July, and fruit until around October.

THE HORSE MUSHROOM, AGARICUS ARVENSIS

This mushroom is one of my favourites, and can grow to a very large size, in some instances, with caps the size of a dinner plate! The caps of these behemoths are white / off-white, to tan, and can be smooth, but are often covered in cracks and scales, particularly in larger, more mature specimens. They are often confused with Yellow Stainers, as they can bruise a mild yellow colour, but rarely in the base of the stem, unlike their toxic cousin. The staining is also far less vivid. The cogwheel-like appearance of the partial veil protecting the gills in younger specimens is also a key indicator of this species, but for me, the easiest way to identify a Horse Mushroom is the aroma, which is heady and distinctly aniseedy. The flavour of this mushroom is strong, like shop bought mushrooms, but richer and more pungent. I find the flavour to be more intense when the gills are darker, almost black. It's not for everyone, so if you prefer your mushroom flavour to be milder, go for younger specimens with pinker gills!

THE CROCODILE AGARIC, AGARICUS CROCODILINUS

Also known as the Macro Mushroom, these white to off-white grassland fungi can grow to a significant size and often have a very distinctive scaly, almost shaggy appearance, particularly in warm, dry weather. Often very stout, the white flesh flushes pink when cut or damaged, which shortly fades to a dull brown / tan colour. These mushrooms have a very distinct, earthy aroma, which I find transfers into their flavour. Their scaly appearance, in addition to their pink flush makes them quite easy to identify. They are however, very appealing to bugs, and even young specimens can be full of creepy crawlies.

THE PRINCE OF MUSHROOMS, AGARICUS AUGUSTUS

This large, beautiful woodland mushroom is rightly called The Prince, as it is often ranked very highly for flavour amongst foragers. Often found growing in association with conifers, this magnificent mushroom has white flesh and a wonderful aroma of bitter almonds, and this distinctly translates into the flavour when cooked. It's brown, concentrically speckled cap is a key identifier of this mushroom, as well as it's long, but very delicate skirt. Like all Agaricus mushrooms, the gills start out very pale, before developing a pink, then brown, then almost black hue as the spores develop. Definitely one for your basket should you be lucky enough to find one. The Prince has a smaller, but equally delicious relative, Agaricus lanipes, also known as The Princess, which is very similar, but stains red when cut or damaged.

THE MEDUSA MUSHROOM, AGARICUS BOHUSII

A rarer find, this large and absolutely stunning agaric grows in woodland, often in association with conifers. It's intricately concentric-pattered cap is a key identifier, in addition to it's tendency to flush red when cut or damaged. The Medusa Mushroom often grows in small clusters that are all joined at the base, looking like a family of snakes. This growth habit, alongside it's snakeskin like patterning is where it gets it's common name.

THE BLUSHING WOOD MUSHROOM, AGARICUS SYLVaticus

These small, but pretty agarics are very similar in patterning to the Medusa Mushroom, and also stain red when cut (hence "Blushing"). Where we live, they tend to grow singly or in small groups under conifers, rather than packed together like the Medusa Mushroom.

Head Out & Explore!

The world of wild agarics may seem complex and fraught with difficulty, but once you've mastered the basics and harnessed the innate familiarity that you no doubt already have with this genus (supermarket mushrooms are Agaricus bisporus, so you already know what they look like!), you'll be gathering them by the basket load. They are a good introduction to edible gilled fungi, and provided you rule out the toxic ones, you can be enjoying them for dinner all through the summer and into early winter.