Morchella esculenta (common morel)
The common morel and related species, popularly known as morels, produce their distinctive fruitbodies in spring and are sought-after edible fungi.
About this species
Morels are well known and distinctive spring-fruiting fungi, with large fruitbodies that have long been sought-after as a culinary delicacy. The common morel was first named by Linnaeus in 1753 as Phallus esculentus, from its broad resemblance to fruitbodies of stinkhorns (Phallus spp.), especially those in which the fleshy spore-bearing mass (gleba) has been lost. However, stinkhorns are basidiomycetes, and are now known to be quite unrelated.
Despite being well-known, the ecology and taxonomy of morels remain poorly understood. Species are known to be variable in form, yet are all remarkably similar in microcharacters, so that their delimitation is uncertain. Molecular study has yet to clarify this. Morels also have a complex ecology which is not fully elucidated, including a saprotrophic phase often involving the formation of underground sclerotia-like structures, as well as a mycorrhizal phase linked to various coniferous trees.
Geography & Distribution
Common morels are widespread and reported from many countries worldwide, and are apparently almost cosmopolitan in distribution. However, due to uncertainty in delimiting taxa in this species complex, M. esculenta sensu stricto may eventually prove to be more restricted in distribution.
Morchella esculenta, Tauberland, Germany (Image: Bernd Haynold, courtesy of Wikimedia Project)
The fruitbodies of Morchella esculenta are variable in size and shape, commonly 10 - 15 cm high but often larger, comprising a stalk and fertile upper part or cap, hollow. The cap is rounded, subglobose to ovoid, or sometimes more elongated and occasionally conical, ‘honeycomb-like’, comprising irregular fertile pits separated by a network of narrow sterile ridges or ribs, greyish to pale yellow-brown, delimited from the stem by a shallow furrow. The stem is well-developed, stout, whitish to cream, sometimes enlarged towards the base, and the surface is often somewhat furrowed and bearing fine scurfy scales especially towards the apex. The spore deposit is deep cream to yellowish, and spores are broadly ellipsoid, smooth and lacking internal oil drops.
The complex ecology of morels has been recognised only in recent years, and many details remain to be elucidated. It seems that their life cycle may involve a saprotrophic phase, with production of sclerotium-like structures and formation of fruitbodies on disturbed, often nutrient-rich soil, alternating with a symbiotic mycorrhizal phase associated with conifers in forests. The latter phase has been demonstrated in association with species of spruce, but may involve other conifers. It is ectomycorrhiza-like but with incomplete development of the Hartig net which characterizes such mycorrhizas, and also involving hyphal penetration of the root cells. They are also considered to be parasitic, hyphal connections to roots of Cornaceae and Oleaceae having been reported as early as 1865; mycorrhizal status has long been mooted. The sclerotium-like structures develop beneath the soil surface and may lie dormant until stimulated to germinate. This may be the reason why huge fruitings of morels, sometimes involving many thousands of fruitbodies, can appear within a year following fires. The post-fire harvest of morels is well known, and of commercial importance in North America.
Threats & Conservation
Although not considered of conservation concern in UK, morels are comparatively rare in parts of Europe and have been placed on provisional red data lists in some countries. Hence, Morchella esculenta as well as M. elata are considered rare in Montenegro and appear on their provisional red list, and M. elata is considered ‘near vulnerable’ in Bulgaria, and ‘vulnerable’ in parts of Poland. Morels are commercially harvested, especially in parts of western North America, and sustainable management policies have been introduced there.
- Culinary delicacy
Morels are a prized culinary delicacy, one of the few edible larger fungi to appear in spring. They are considered one of the best of the edible fungi, sought-after and commercially harvested in North America and elsewhere. The species can now be successfully cultivated and may become of economic significance in this respect. The fruitbodies are considered quite nutritious, containing high-quality protein, and being rich in minerals and low in calories, though as noted above, they must be cooked and never eaten raw.
Morels also have various medicinal uses, particularly in parts of Asia. For example, in traditional Chinese medicine they have been used to treat indigestion, excess phlegm, croup, and shortness of breath. Bioactive compounds have also been reported in Morchella, based on study of cultured mycelia, including some with anti-tumour, antioxidant, and anti-inflammatory activity. Compounds linked to immune-system enhancement have also been reported.
Other MorelsMore Information
It is not certain how many Morchella species can be recognised in Britain, but at least three and probably several others occur. Of these, the ‘half-free morel’ (Morchella semlibera; sometimes referred to Mitrophora) differs in having the lower part of the cap entirely free from the stem. It has a rather conical cap with some dark, vertical ribs, and is a distinctive species, the only one which can be readily identified. Other morels are very variable in form and colour, even from within a single population, and can look quite different as they mature.
The microcharacters hardly vary between species, so that the true number of species and their delimitation is still uncertain. Some workers recognise many based on small differences in form, others only a few. Two main groups can be distinguished, the ‘black’ morels with rather conical caps and parallel vertical ribs, and the ‘yellow’ morels, including M. esculenta, with irregular ribbing and caps which are variable in form but not usually conical. At least three species have recently been recognised in the M. esculenta group in Europe. The conical morels (M. elata group) are equally problematic. These differ from M. esculenta in having mostly parallel, usually blackish, vertical ribs, with horizontal cross-ribbing, and quite coarse scurfy scales on the upper stem.
Morels at Kew
Morels have occasionally been recorded in the gardens at Kew but are uncommon. Look for them in suitable areas, such as on woodchip mulch, in April and May.
Herbarium collections of Morchella esculenta from throughout its range are maintained in the Kew Mycology herbarium and, although not accessible to the general public, are available for study by mycologists.
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