Agaricus arvensis: The Ultimate Mushroom Guide
About The Agaricus arvensis Mushroom
This edible mushroom is usually quite large. It is often larger than the biggest Portobello.
Agaricus arvensis is white to slightly tannish or yellowish with long stems that have a hanging veil. The caps have fairly obvious scales and are very regular in shape. The edge of the cap (margin) often has veil remnants making it slightly ragged.
The genus Agaricus has a worldwide distribution, with up to 90 species recorded in Europe and more than 40 species recorded in the United Kingdom. Estimates for the worldwide totals of Agaricus species vary but are likely to exceed 200.
Other names: Horse Mushroom, Snowball Mushroom, Abrahams.
Agaricus arvensis Identification
The cap of Agaricus arvensis matures at 8 to 20cm (exceptionally to more than 30cm) diameter. White but yellowing gradually with age, smooth or finely scaly, the cap is initially spherical and expands until it is flat or nearly so. The thick flesh is white and firm. The cap turns yellowish where bruised, and old caps often take on a yellow-brown tinge.
At first pale pink, darkening, and then becoming brown, the gills of the Horse Mushroom are free and crowded.
Up to 10cm tall, the parallel stem usually a small bulb at its base and a robust, double ring with a cog-wheel form on the underside.
The solid stem is smooth above the ring but sometimes finely scaly below. Its diameter ranges from 2 to 3cm.
When cut at the stem base, Agaricus arvensis does not rapidly turn bright yellow - a useful visual distinction between this edible mushroom and the poisonous Yellow Stainer, Agaricus xanthodermus, whose stem base turns chrome yellow as soon as its cut flesh is exposed to air.
Ellipsoidal, smooth, 6-9 x 4-6µm. Has a dark purple-brown spore print.
Agaricus arvensis appears in manured meadows and beside bridle paths and other places where there is plenty of decaying organic matter, upon which it feeds saprophytically. The Horse Mushroom is one of the largest and most distinctive fungi in its genus, often forms fairy rings many metres in diameter in permanent pastures.
August to November, typically a week or two later than the Field Mushroom, Agaricus campestris, with which the Horse Mushroom is sometimes confused.
Agaricus arvensis Look-Alikes
This mushroom could be confused with any of the poisonous Agaricus - such as the Yellow Stainer (Agaricus xanthodermis) or the Inky Mushroom (Agaricus moelleri), but these smell unpleasant of phenol or bottled ink and/or stain strongly yellow, particularly in the base of the stem, when bruised or cut.
When the gills are white, confusion with poisonous Amanitas could also be possible, so very young specimens are best avoided by novice foragers.
Agaricus arvensis Medicinal Properties
Some research has been undertaken into the potential antioxidant activity of the Horse Mushroom. It has been used to treat lumbago and tendon pain in China.
Agaricus arvensis Taxonomy & Etymology
First described from Bavaria in 1762 by Jacob Christian Schaeffer, who gave it the name Agaricus arvensis (although like many mushrooms it later spent some time in the genus Psalliota before reverting to its original Agaricus home), the Horse Mushroom is a cosmopolitan mushroom.
Synonyms of Agaricus arvensis include Agaricus arvensis Schaeff., Psalliota arvensis (Schaeff.) Gillet, and Agaricus fissuratus F.H. Møller. (The latter is treated by some authorities as a separate species; it has a cap that crazes when old and its spores are on average somewhat smaller than is typical of Agaricus arvensis.)
The specific epithet arvensis means 'of the field' or 'of meadows' - a reference to the habitat in which the Horse Mushroom is most commonly found. Less obviously, the common name may not be the more obvious to horses and its apparent appetite for horse manure (and hence the common occurrence of this mushroom near stables or fields in which horses graze) but, some people have suggested, an allusion to the large size that these mushrooms can attain.
Agaricus arvensis Cooking Notes
This mushroom has a strong flavor and lend themselves to most cooking processes.
Cook them very shortly after picking so you can capture that strong anise/almond aroma that can dissipate somewhat after short storage.
Tempura is a great technique for retaining this anise/almond character. The more mature they get, the stronger the flavor.
They are excellent sautéed, as tempura, microwaved, dried, soup, grilled, stuffed, etc.
Agaricus arvensis are great with steak and other strong-flavored red meat.
A large horse mushroom cap can be used as the "dough" for pizza.
Recipe: Cabbage and Horse Mushroom with Pickled Plums
3 c shredded green cabbage, lightly salted, set aside
1 c sliced horse mushroom
1 T Umeboshi plums, pits removed (about 5)
2 T vegetable oil
2 t dark sesame oil
½ t sugar
salt to taste
How to cook
Over a medium flame, heat the oils in a large skillet.
Add the mushrooms, and saute for one minute.
Add the salted cabbage and stir until just wilted.
Stir in the sugar and plums.
Cook for one more minute.
Serve hot or at room temperature. Serves four as a first course.
Recipe: Stuffed and Baked Horse Mushrooms
2 Large but round Horse mushrooms
Half a red onion
1 Tbsp Butter
1 Tbsp Stilton
1 Tbsp Breadcrumbs
From the garden
Small bunch of herbs including Parsley, Coriander, Dill, Chives and Thyme or you could go with Wild herbs and use Sorrel, Wild Marjoram, Cow Parsley, Water Mint and Wild Chives
How to cook
Get the oven on to 200C.
Start by cleaning the Mushrooms, remove the stalks and chop, reserving them until later. Next place the Horse mushrooms onto a baking tray, gill side up. As the mushrooms are quite big we want to be generous with the flavor so divide the batter into two and add the butter to each mushroom. Season with salt and freshly ground black pepper and place a sprig of fresh thyme in both the mushrooms (if the Thyme stalks are a little woody pulls the leaves off and place just the leaves in the base of each of the Horse Mushroom caps.
Place into the oven and bake for 10 minutes.
Whilst the Horse Mushrooms are baking, heat some olive oil in a frying pan, fry the chopped onion for a minute or so and add the chopped mushroom stalks and cook until soft.
Chop your herbs.
Once the mushrooms have cooked for 10 minutes, spoon the onion and mushroom stalk mixture into the two baked mushrooms and sprinkle each of the mushrooms with the herbs reserving half. Break the Stilton with your fingertips and place it on top of the mushrooms. Finally sprinkle breadcrumbs over the top of the cheese, finish with a final swirl of Olive Oil, and then put back in the oven until for about 5 minutes, don’t remove until the cheese is melted and bubbling!
To serve, place the mushrooms onto a serving plate and sprinkle over the remaining chopped fresh herbs.
Recipe: Horse Mushroom Croustade
100 g (4 oz) soft breadcrumbs
100 g (4 oz) ground almonds or other nuts
50 g (2 oz) butter
100 g (4 oz) flaked almonds
pine kernels or hazelnuts
1 clove garlic, crushed
½ teaspoon mixed herbs
450 g (1 lb) mushrooms
50 g (2 oz) butter
2 heaped teaspoons flour
450 ml (¾ pint) milk
1 teaspoon chopped parsley
How to cook
Croustade: mix breadcrumbs and ground nuts and rub in butter, cut in small pieces.
Add flaked almonds, garlic, and herbs. Mix well and press down into an ovenproof dish, making a layer about 1 cm (½ in) thick. Bake at 230˚C (450˚F, Mark 8) for 15–17 minutes until golden brown.
Topping: wash and slice mushrooms, sauté in butter until tender, add flour and when it froths remove from heat and stir in milk.
Return to heat until thickened, then season. Spoon mixture on top of croustade, top with skinned and sliced tomatoes, and a little salt, pepper and nutmeg. Return to oven for 10–15 minutes. Serve decorated with parsley.
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