To be honest, I don’t really see many Fieldcaps, scientifically known as Agrocybes (Agro meaning Field and cybe meaning cap/head). Many have a fruiting season from late spring through to autumn, hence they are very conspicuous when seen during the summer months, when there is little about.
This is my second find in the same month of two different species of Agrocybe, but I’ll focus on the latter example here. Although its common name suggests its habitat, the Poplar Fieldcap (Agrocybe cylindracea) only grows in association with trees, namely Poplar and Willow – just like our native Black Poplar as in this case. (More info on identifying the Black Poplar here). It’s really not that common but has an ‘all year round’ season, and rather than being seen with trees, it can also be found out of its natural surroundings such as on rotting wood mulch and garden chippings.
I found this small collective at a local park that seemed to be growing in the grass, near a Poplar tree. As I always say, check out the environment, because at first glance some things can be deceptive. On closer inspection, the stem bases were actually attached to the gnarly roots just hiding beneath the grass, embedded slightly deeper in the soil. This fact alone helped as a great clue to its identity.
I caught them a little late though. When younger (as you will see in some of the pictures below) the whitish/pale buff caps are rounded and smooth and range from 4cm to 6cm across. After a short time the caps expand (up to 10cm approximately) and often dry out to leave a ‘crazed’ surface pattern and the margin often becomes wavy and split. Initially the adnate (or slightly decurrent) gills are pale but soon mature to dark tobacco-brown as the spores mature. These mature spores will fall onto the persistent ring beneath, leaving a dirty brown stain on the upper side.
Although edible I don’t hear much about what people think about them. I simply assumed they were just not held in any high regard. But after sampling a couple of the younger, more fleshy samples, I was pleasantly surprised. The smell and taste is typically ‘mushroomy’ but much milder with a ‘nutty’ hint. Very nice indeed. I would definitely recommend them.
So, for a species that isn’t terribly common I was lucky to find these… Well, actually I was told about them by a friend. It’s pays off when you ask all your friends and family to keep a look out. All those extra pairs of eyes are very useful. Happy hunting.
QUICK ID TABLE: POPLAR FIELDCAP Agrocybe cylindracea
CAP / FLESH
4-10cm across. Pale. Whitish with yellow-brown centre. Darker with age or brown from spore deposits of other mushrooms. Rounded at first, maturing flat and often cracking.
5-10cm x 1-1.5cm. Creamy white. Darkening with age. Persistent ring often coloured brown on the upper side by falling spores.
GILLS / SPORE PRINT
Adnate or slightly decurrent. Initially cream, maturing to tobacco brown colour.
HABITAT / SEASON
In groups, sometimes overlapping, growing with Poplar and Willow. All year.
Edible. Mild and slightly nutty flavour.