Morchella eohespera — Cosmopolitan black morel

Morel

Morel2 sectioned longitudinally (left), photograph by Ludovic Le Renard; Morchella tridentata3 (right), photograph by Adolf Ceska

Morel

A morel15 sliced in half to show that the pits and ridges of the cap are attached to the hollow stem, photograph by Ludovic Le Renard.

Warning: Do not confuse poisonous false morels (Gyromitra species), which have brain-like rounded lobes or saddle-shaped heads with edible true morels. In true morels, the outermost surface of the head has narrow, flattened ridges that form rims around deep pits.
The description of the cosmopolitan black morel applies in large part to other species, although average fruitbody and spore sizes vary.


Odour: Mild.
Head: ~3–6 cm tall, roughly conical, with deep pits rimmed by ridges, beige, tan, brown, or almost black. Cut the fungus lengthwise to verify that it is hollow from just under the tip of the head down most of the length of the stem (see 'field characters'). In most species, the whole head is fused to the stem along its entire length. In Morchella populiphila, a species associated with poplar trees along rivers, the bottom of the head hangs free as a skirt but it is still attached to the stem along its top cm or so.
Stems: 2.5–4 cm long x 1.5–3 cm wide (varies by species, occasionally longer or wider). Usually lighter than the head, whitish to tan. Hollow.
Spores: (18–) 20–24 (–40) x 11–14 (–24) µm, contents homogenous without prominent oil droplets.
Habitat: On ground in forests. Other species of black morels pop up in wood mulch and wood chips; fire morels can be abundant in spring following a forest fire. Whether mainly saprotrophic or ectomycorrhizal remains unclear7,8.
Geographical range: Known from North America, Europe and China, and likely widely distributed across the Northern Hemisphere.

The many species of morels share the same general shape and all are considered edible for most people, after being cooked. Gyromitra and Helvella species resemble morels in size and colour but have lobed or saddle-shaped heads. Gyromitra and Helvella species contain toxic, carcinogenic monomethylhydrazines9 and eating them poses a substantial risk. Verpa bohemica also fruits in spring and resembles morels except that the head is attached only at the top of the stem. Verpa species are more likely than morels to cause gastrointestinal upsets. Canned and dried morels have sometimes been contaminated with Gyromitra or Verpa, resulting in at least one serious illness and leading the US Food and Drug Administration to check imports and refuse entry of morels contaminated with these other fungi10.

Although widely appreciated as edible species, morels have caused a surprising number of gastrointestinal upsets, sometimes accompanied by neurological disorders11. From 1985-2006, 146 cases of poisoning were tallied in a North American Mycological Association report12. Eating raw morels, large quantities of morels, or morels that were old and perhaps contaminated with bacteria apparently contributed to poisonings in some, but not all cases11. Evidence for an interaction of alcohol with morel poisoning is equivocal.
 

Toxins: unknown. Gastrointestinal symptoms may be due to hemolysins, which damage red blood cells but presumably evaporate or are destroyed by cooking11.

Symptoms: Most common symptoms are gastrointestinal (67%)11. From ~15 min to 13 hours after eating morels, symptoms include nausea, vomiting , cramps, and diarrhea. Neurological symptoms arise 2 hours to 1 day after eating and include vision disorders, dizziness, drowsiness, hand tremors, disorientation, numbness and sensitivity to sound, chills. Most people recovered within a day, although in one individual, tremors lasted for a month11.

Treatment: Contact your regional Poison Control Centre if you realize you or someone you know has become ill after eating morels. Poison centres provide free, expert medical advice 24 hours a day, seven days a week. If possible, save the mushrooms or some of the leftover food containing the mushrooms to help confirm identification.

Poison Control:
British Columbia: 604-682-5050 or 1-800-567-8911.
United States (WA, OR, ID): 1-800-222-1222.

Cases of poisoning from morels:

  • In an infamous retirement banquet for Vancouver's chief of police, one of the city's best hotels served a pasta salad containing raw morels that poisoned 77 of the 483 attendees13. Victims reported nausea, diarrhea, vomiting, and cramps. Some reported a hive-like rash, not a usual symptom of poisoning by morels but possibly attributable to another raw mushroom, the shiitake Lentinus edodes, also in the salad.
1
MyCoPortal. Mycology Collections Portal, <http://mycoportal.org/portal/collections/harvestparams.php> accessed July 2018.

2
Specimen Morchella eohespera UBC F24332 MO 95658, GenBank #MH718195.

3
Kuo, M. et al. Taxonomic revision of true morels (Morchella) in Canada and the United States. Mycologia 104, 1159-1177, doi:10.3852/11-375 (2012).

4
Arora, D. Mushrooms Demystified. Ten Speed Press, Berkeley, California (1986).

5
Siegel, N. & Schwarz, C. Mushrooms of the Redwood Coast. A Comprehensive Guide to the Fungi of Coastal Northern California. Ten Speed Press, Berkeley, California (2016).

6
Voitk, A., Beug, M. W., O’Donnell, K. & Burzynski, M. Two new species of true morels from Newfoundland and Labrador: cosmopolitan Morchella eohespera and parochial M. laurentiana. Mycologia 108, 31-37, doi:10.3852/15-149 (2016).

7
Dahlstrom, J. L., Smith, J. E. & Weber, N. S. Mycorrhiza-like interaction by Morchella with species of the Pinaceae in pure culture synthesis. Mycorrhiza 9, 279-285, doi:10.1007/PL00009992 (2000).

8
Hobbie, E. A., Rice, S. F., Weber, N. S. & Smith, J. E. Isotopic evidence indicates saprotrophy in post-fire Morchella in Oregon and Alaska. Mycologia 108, 638-645, doi:10.3852/15-281 (2016).

9
Berger, K. J. & Guss, D. A. Mycotoxins revisited: Part II. J. Emerg. Med. 28, 175-183, doi:10.1016/j.jemermed.2004.08.019 (2005).

10
Gecan, J. S. & Cichowicz, S. M. Toxic mushroom contamination of wild mushrooms in commercial distribution. J. Food Prot. 56, 730-734 (1993).

11
Saviuc, P., Harry, P., Pulce, C., Garnier, R. & Cochet, A. Can morels (Morchella sp.) induce a toxic neurological syndrome? Clin. Toxicol. 48, 365-372, doi:10.3109/15563651003698034 (2010).

12
Beug, M. W., Shaw, M. & Cochran, K. W. Thirty-plus years of mushroom poisoning: Summary of the approximately 2,000 reports in the NAMA case registry. McIlvainea 16, 47-68 (2006).

13
Kroeger, P. 'Yumm,' said the police chief. Mushroom the Journal Fall, 34 (1991).

14
Specimen Morchella tridentina UBC F28215, GenBank #MH718201.

15
Specimen Morchella cf. esculenta UBC F33029, GenBank #MH718237.