Gyromitra esculenta (False morel)

English Name: False Morel (also known as Lorchel and Turban Fungus)

(other scientific names include Helvella esculenta and Physomitra esculenta)

This is one of the larger, stalked members of the ascomycete division (divisions within the fungi kingdom). The fertile surface is the outer surface of the brown, convoluted ‘cap’, which is effectively an inverted ‘cup’ (cup or disc shapes being very common amongst the ascomycete fruiting structures). The colour will vary from yellowish brown, through red brown to almost black – although the latter can be the result of dry conditions. The cap area is supported on a relatively short, white (but sometimes almost pale violaceus brown) stipe (stem), which is furrowed and contains several hollow chambers. The whole structure can be up to 20cm across, with the cap area irregularly fusing with the stipe.

Of particular interest with this species is the question of its edibility. With a specific name ‘esculenta’ inferring that it should be something good to eat, it might come as a surprise to find out that, without very careful preparation, this fungus can cause serious illness or even death. Ted Blackwell, in an excellent article in the Herefordshire Fungus Survey Group newsletter (No. 15, p13) explains the situation. The reason for the title of the piece ‘But it’s not rocket science!’ becomes clear as the story unfolds.

In Eastern Europe the species has been considered an excellent edible fungus but always after parboiling twice and throwing away the water both times (I know several healthy Finns who regularly do this!) Even so, stories of occasional poisoning have been told – the cook was ill or one person amongst a group of others who stayed well.The symptoms displayed by those taken ill after eating Gyromitra turned out to be very similar to those displayed by workers on the American space programme who were falling ill at the time. The space worker’s illness was traced to exposure to a certain type of rocket propellant fuel known as Monomethylhydrazine (MMH). Gyromitra esculenta was found to contain a substance named gyromitrin. This substance it turns out, is broken down by the action of stomach digestive acid, to MMH! Once this was realised, the poisonings made more sense. The fungal toxin is volatile and distils off at a lower temperature than boiling water. Thus if boiled for sufficient time and the water discarded, the toxin is lost. This might explain why the cook becomes ill – through the inhalation of toxic vapours released during the cooking process. The diners meanwhile could be unaffected although if not all of the fungi were thoroughly boiled that could explain some episodes where only one diner was taken ill.

All of this information is rather important when you consider how closely this species resembles a highly acclaimed edible species Morchella vulgaris (Morel). As ever with fungi, you do need to be sure that you know your edible species and its look a likes thoroughly. For me Gyromitra has convolutions whilst Morchella has a honeycomb type cap (see bottom photo opposite) – but it is easy to convince yourself either way if you have not really got your head around the differences, so do be very careful!

Fruiting:

This is a spring species, with most of the records in the months of April and May. There are scattered records in February and March and a couple from June. Morchella vulgaris displays a very similar fruiting pattern as do several other delightful members of the Morchellaceae including Verpa conica, Morchella (or Mitrophora) semilibera and last year's April Fungus of the Month, Gyromitra ancilis. If anybody has any good images for the first two species, do send them in to scottishfungihub@gmail.com – I don’t see these much in the Central Highlands and don’t have any good pics myself – we could feature them next spring.

Habitat:

This species is thought to be a wood rotter and is often found in sandy soils almost always associated with coniferous trees. It turns up in gardens as well as woodlands and just occasionally is said to be associating with broadleaves. I have once found it growing on a very dead fallen birch trunk.

Distribution:

Widespread in the UK but only common in some areas of Scotland (a couple of interesting records in the sea off the east coast of England on the NBN map!). There appears to be a central and eastern distribution in Scotland. Is that a genuine pattern or are there fewer mycologists that have recorded on the west of Scotland in the spring? The total number of sites for this species on the Fungal Records Database of Britain and Ireland is 294 and 119 of these are in Scotland.

Please remember to submit your records to your local recording group or via the Scottish Fungi online recording form.

Above: Gyromitra esculenta (False Morel) showing differently coloured caps

Below: A species of Morchella showing the honeycomb cap in contrast to the convoluted cap of Gyromitra above

Liz Holden April 2012

Morchella elata

G.esculenta distribution from the National Biodiversity Network Gateway:

The National Biodiversity Network Gateway records from FRDBI, NESBReCandHBRG datasets are shown on the above maps (see terms and conditions at http://data.nbn.org.uk). Data providers and the NBN Trust bear no responsibility for any further analysis or interpretation of the information in the map.