white mushroom in grass – The Mushroom Diary – UK Wild Mushroom Hunting Blog

Right now there are quite a few Agaricus (mushroom) species. I have already seen many species in varying urban habitats. I was especially lucky when I stumbled across these beauties literally round the corner from my house on a large grassy verge.

The most welcome Horse Mushroom (Agaricus arvensis) is a great tasty mushroom that grows in most types of grassland, mainly permanent pasture land, but to reiterate, in this case it was a small grassy front lawn/verge.

They’re often found growing in large rings and this was no exception, even though it was only a partial ring. Still plenty to go around though.

The word ‘Horse’ used in the English name doesn’t reflect on where they can be found, such as fields with horses in (which is a common misconception) but is in reference to their large size. The largest in this group was 15cm across, the size of a small plate. 20cm is the maximum size on average and even at these dimensions, they are still relatively fresh and ready for the pan. If you find what appears to be a Horse Mushroom, but has a 30cm diametre cap, then you’ve probably found a Macro Mushroom (Agaricus urinascens), very similar indeed to our Horse Mushroom but slightly more scalier on the cap. That’s another story for another time.

People often avoid the Horse Mushroom because of the yellow (pale ochre) colouring that appears on the cap as it ages. Some are unsure that they could be dealing with the rather unwelcome ‘Yellow Stainer’, an extremely common look alike that could cause nasty gastro upsets (read all the about the Yellow Stainer in this post). In fact, some Agariucus xanthodermus were quite happily growing on a grassy verge nearby that very day!

But have no fear, the Horse Mushroom has some key characteristics that set it apart from the rest. Initially I always do the ‘Yellow Stainer’ test in which I rub the side of the cap and get the base of the stem out of the ground and snap it in half. If there’s some ‘strong’ chrome yellow colouring I simply avoid it. The Horse Mushroom has no extreme colouring like this and no colouring at all in the base of the stem flesh.

If you look around and find a very young example, the gills will be veiled by the what is to become the ‘ring’ on the stem (see picture below). A distinctive jaggedy ‘cogwheel’ pattern runs around the outer circumference of the membrane. This is always a good sign.

The young gills are white at first and turn pink, then eventually chocolate brown as time goes by. I found these at a good time and I didn’t hesitate at all in collecting some for my tea, leaving a few to do their thing.

They eventually ended up in a lovely mushroom soup (if I don’t mind saying so myself). I hope you too have some good luck in finding these beautiful and tasty mushrooms. Enjoy.

The Horse Mushroom can grow up to 20cm in diametre. Notice the ‘cogwheel’ pattern on the veil, covering the gills of the younger mushroom (bottom left).

QUICK ID TABLE: HORSE MUSHROOM Agaricus arvensis

CAP / FLESH

5 – 20 cm across. Initially domed cap expanding out. Creamy white, yellowing with age. Flesh firm and thick. Slight smell of aniseed (more so when young). Veil on underside initially covers gills. Has a ‘cogwheel’ pattern.

STEM

8-10cm x 2-3cm. Same colour as cap. Often becomes hollow.

GILLS / SPORE PRINT

Free from stem apex. White at first, greyish then pink and finally chocolate brown with age.
Spore Print: Dark purple brown (see how to take a spore print here).

HABITAT / SEASON

Grassy pastures, lawns and sometimes grassy verges. Often in rings. Late summer – autumn. Common.

EDIBILITY

Edible and excellent. Good mushroomy flavour.

The Genus AGARICUS (Wood Mushrooms/Mushrooms): Characteristics to look out for:

• Many discolour yellowish, reddish or pinkish when cut or bruised.
• Those that discolour bright/chrome yellow should be avoided for consumption.
• Gills in young specimens are often pink (white in a few) – maturing darker brown.
• Make note of any smells, such as aniseed or a typical strong ‘supermarket’ mushroom smell.

Well, this weekend autumn has certainly stamped its initial authority on the land. Some leaves have already fallen in areas around the urban edges of my town. But I am a die-hard lover of fresh autumn mornings. There is still the summer warmth clinging on, but that zingy freshness of autumn is making itself known.

A call from one of my friends (literally working up the road at a school) was my waking alarm clock this morning – “We’ve got lots of white mushrooms going on here, a lot of them eliptoid shaped! Come and have a look if you can”. Well, it doesn’t take much to get me interested in a free meal, and I always love it when my friends let me know of any mushroom discoveries going on. Bless them. And as I work for myself, I wasn’t going to upset the boss by being late for work.

So, at just gone 9am, on a lovely misty autumn morn, I’d arrived at his school. Lots of grass around and lots of Shaggy Ink Caps around too (they also appear abundantly in summer). After a weekend of constant drizzle it had obviously encouraged these beauties to sprout forth. Excellent.

The Shaggy Ink Cap (Coprinus comatus) – (comatus meaning ‘long haired’), is (naturally) a member of the ink cap family. As they get older, the cap opens (though not out flat) and eventually goes through a stage of dissolving and releasing an inky black fluid. It’s very similar cousin – the Common Ink Cap is similar in size and shape but has a smooth surface. It can be poisonous depending if you’ve some alcohol or not! See the Common Ink Cap (Coprinus atramentarius) post – read all the details here.

The common name alone gives a clue in identification to this edible and lovely mushroom over it’s sinister (though not deadly) cousin. Its shaggy appearance is caused by the white or pale-brown scales on its long, rugby ball shaped, cap. There is a drastic change in appearance depending on at what stage you find it. Young specimens don’t show much stem at all, in fact it can be hidden, depending on the height of the grass it’s in – and the brilliant white cap is unblemished, though sometimes showing light brown colouring at it’s tip (which persists). But as it grows older, the cap opens up and then shrinks, as it slowly dissolves into inky black oblivion! I know that sounded a bit dramatic but I thought I’d get the point across. A lot of people, on first encounters, see the younger specimen and older specimen as a different mushroom. And I really can’t blame them, they appear so different.

A spore print for identification is not needed I think though. This mushroom speaks out loud for itself, and if you find it later in life, its obviously going to have a ‘black’ feel about it! It has a good salty flavour and is definitely worth a taste, I love it. Try it out, it’s a wonderful mushroom*. Look out for it this October, not only in grassland but on roadsides and disturbed ground even at woodland edges/woodland vegetation.

And if you fancy it, also take a look at using this ink for literary purposes and make your own ink! Great stuff.

The Shaggy Ink Cap from very young to old (as black ink starts to be produced)

Always try a little sample if you’re trying an edible mushroom for the first time, just to see if it agrees with you. The first time I tried this lovely mushroom I had a mild reaction of little red bumps in my mouth and what felt to be a slight hot flush! There was no unpleasantness involved and wasn’t at all serious. It soon passed. It’s just good to check your body is OK introducing it to the new food. It’s just like eating abroad really!

The Genus COPRINUS & Related (Inkcaps): Characteristics to look out for:

• Most species gills dissolve into an inky black liquid as the black spores ripen.
• Growing on the ground, wood or dung.
• Many young species have woolly veil. Felty scales are often left on the mature specimen.
• Smaller species have distinct radial markings on the cap.

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