Morchella semilibera, commonly referred to as the half-free morel, is a genetically distinct member of the Morchellaceae family, with its distribution strictly limited to Europe and some parts of Asia. This medium-sized yellow-brown mushroom is characterized by a honeycomb-like cap that is attached to the stalk from its midpoint upwards (half-free cap attachment).[i]
Morchella semilibera, from a taxonomic perspective, is a very confusing species. Until very recently, it was believed that M. semilibera grew in both North America and Europe. However, recent molecular phylogenetic studies along with comprehensive studies of morphology, ecology, and distribution patterns of various Morchella collections revealed that Morchellaceae demonstrate a high degree of continental endemism. Consequently, this revelation necessitated a substantial taxonomic revision, as the existing European species names could not be applied to North American morels, and vice versa. As such, the 2012 Revision of Morchella taxonomy conducted by Kuo and colleagues, reclassified Morchella semilibera as a strictly European species. While those half-free morels found in North America, previously identified as M. semilibera, were also reclassified as Morchella populiphila found in Western North America and as Morchella punctipes in Eastern North America.[ii]
Synonymous names/species of Morchella semilibera include Phallus crassipes, Phallus gigas, and Phallus undosus.
Identification and Description[iii]
Cap: The bell-shaped cap of this species measures 1 to 5 cm in both height and width. While young, the mushroom takes on a bluntly conical, round, or oval shape, which gradually transforms into a primarily conical form as it matures. The cap is fused with the stem from about the middle upward, while the margin, or lower edge, of the cap is free from the stalk, often flaring outward, away from the stalk as the mushroom ages. The surface of the cap has a honeycomb-like pattern formed by pits and longitudinal/lengthwise ridges. The pits on the cap are notably large and elongated, with colors varying from yellowish-brown to brown or grayish-brown. The ridges, which run vertically on the cap’s surface, have color ranging from yellowish-brown to brown or olive-brown, usually slightly darker than the pits. Over time or as the mushroom dries out, the ridges may darken and even become blackish in appearance. On the underside, the interior of the cap appears whitish or pallid and has a roughened texture.
Flesh: The flesh of this species is thin and fragile.
Stem: The stem of Morchella semilibera measures approximately 3 to 10 cm in length and 1 to 2.5 cm in thickness at its apex. As the stem ages, it can become equal or thicker towards the base. Fragile in nature, the stem exhibits a color range from white to yellowish. Its surface is often visibly rough, often having scurfy granules, which may arrange themselves into longitudinal furrows/grooves/ribs resembling a “texture of a cow’s tongue”. Moreover, the stem is typically hollow in cross-section, providing a characteristic feature of this species.
Spores: The spores of this species measure 24-34 by 12-15 µm in size. They are hyaline, smooth, and elliptic, with or without apical clusters of oil droplets (guttules).
Spore print: This half-free morel has a cream to pale yellow spore print.
Flavor and Edibility: Morchella semilibera is considered edible, but it is more fragile and not quite as flavorful as other Morchellas. Although there are certain caveats to consuming Morchellas.
Habitat: This species is often found growing solitary to gregarious on the ground in open woods and under hardwood trees (Oak, Beech, Liriodendron, Alder, etc). It also prefers sandy soil with good drainage.
Range: As mentioned, M. semilibera is a strictly European species that can also be found in some parts of Asia. As such specimens of this mushroom can be found throughout mainland Europe (i.e. Germany, France, etc).
Fruiting Season: The fruiting season of Morchella semilibera displays a distinct specificity. Described as having “intermediate fruiting behavior,” this species tends to emerge in a timeframe that follows the appearance of Verpas (Thimble/Early Morels) and precedes the emergence of other Morchella species. Generally speaking, M. semilibera will start fruiting from early spring, usually in March, April, or May.
Look-A-likes[v]
The identification and differentiation of Morchella is relatively straightforward if one focuses on its distinctive “half-free” cap macro-morphology, unique Europe-restrictive geographic distribution, and intermediate fruiting season.
Despite its distinct characteristics, Morchella semilibera can frequently be mistaken for various Verpa specimens, particularly Verpa bohemica. This confusion arises primarily when M. semilibera mushrooms reach an advanced stage of maturity. At this point, their caps may shrink, resembling the “heads” commonly associated with Verpa mushrooms. Additionally, the stems of older M. semilibera mushrooms can significantly elongate, mirroring yet another typical feature of Verpa species. Thankfully, distinguishing between these two species, Morchella semilibera and Verpa bohemica, can be accomplished through several key factors. First, the attachment of the cap to the stalk, habitat preferences (including soil type), and fruiting times can provide initial clues. However, the most crucial distinguishing feature lies in the structural dissimilarities of their stalks. Verpa species possess non-hollow stems that are filled with cottony filaments, while Morchella species, including M. semilibera, have hollow stems. Further microscopic examination can provide additional and the most accurate/reliable method for definitive differentiation. Notably, V. bohemica exhibits larger spores, with approximately 2-3 spores contained within each ascus. In contrast, the European Half-free morel, Morchella semilibera, has smaller spores, typically with around 8 spores present within an ascus.
Other species that Morchella semilibera may have to be differentiated from are other European Morels such as Morchella esculenta and Morchella elata. These species can be adequately distinguished by examining their cap attachment. In both Morchella esculenta and Morchella elata, the caps are attached to the stalk at the base of the cap, as opposed to Morchella semilibera, where the cap attaches from approximately the middle portion.
The last group of mushrooms that may have to be differentiated from our species include the poisonous false morels Gyromitra caroliniana and G. Brunnea. These toxic mushrooms can be distinguished from true morels, such as Morchella semilibera, by their specific characteristics. False morels typically exhibit reddish caps with distinct features such as wrinkled, lobed, or brain-shaped textures. Additionally, their stalks are dense and solid rather than hollow.
Toxicity, Safety & Side Effects[vi]
Morchella semilibera is generally considered safe and non-toxic for consumption when properly prepared and cooked. However, individuals should avoid consuming very dark-colored specimens as they represent very old and overmature mushrooms which are known to cause gastrointestinal upset. Furthermore, individuals should avoid consuming morels with alcohol, as this combination is reported to cause gastrointestinal upset as well.
References:
[i] McKnight VB, McKnight KH (1987). Half-free Morel A Field Guide to Mushrooms: North America. Peterson Field Guides. Boston, Massachusetts: Houghton Mifflin. (pp. 40-41)
[ii] Kuo, Michael, et al. “Taxonomic revision of true morels (Morchella) in Canada and the United States.” Mycologia, vol. 104, no. 5, 2012, pp. 1159–1177
[iii] Kuo, M. (2012, October). Morchella punctipes.
[v] D. Arora (1986) Morchella semilibera In “Mushrooms Demystified: A Comprehensive Guide to the Fleshy Fungi,” Ten Speed Press, Berkeley (pp. 791–792)
[vi] Lincoff, G. (1981). Half-free Morel. In National Audubon Society Field Guide to North American mushrooms (pp. 328–329). Knopf.
