If you’re interested in foraging mushrooms, then you’re almost certainly familiar with the wonderful world of morels. The Morchella genus contains many choices of highly prized edible mushrooms. These mushrooms bring out mushroom hunters in droves every year throughout their growing regions. Prior to the DNA analysis of mushrooms, morels have been loosely typified based on various physical features. Now, thanks to mycologists, we know that types of morels are classified into three clades based on evolutionary divisions.
In this guide, we’ll cover the overall fungal classification of morels. We will also discuss the three clades of morels (with a focus on North American species). Finally, we will describe a species in each clade.
So, without further ado, let’s jump in!
Morels: Fungal Classification
Morels are wonderfully unique-looking mushrooms of the Ascomycota (sac fungi) phylum. These mushrooms belong to the Morchellaceae family, which contains the Morchella, Verpa, and Disciotis genera. “True morels” belong to the Morchella genus, of which there are at least 20 North American species. After years of collecting and analyzing morel data through the Morel Data Collection Project, in 2011, mycologists classified morels into three distinct clades:
- The rufobrunnea clade- contains only two species, one of which is in North America.
- The esculenta clade- contains five species in North America
- The elata clade- containing 14 species in North America
Confirming the Three Types of Morels Through DNA Analysis
These clades represent the three major evolutionary groups in the Morchella genus. The DNA analysis of these species debunked a few common ways of creating types of morels based on morphological traits. For instance, grey “types” of morels mostly turned out to be immature fruiting bodies of yellow morels. These grey types had previously been separated in many older guides. Additionally, DNA analysis showed “greenie” morels, called such for their green tinting on the cap, were, in fact, not a distinct species. The green tinting can occur across various species.
The takeaway here is that evolution is a massively complex process. Separate species, even ones very distantly related, can develop traits that look the same to the naked eye. As genetic analysis in mycology continues, we’ll likely continue to see some debunking of categorizing mushroom species or genera.
However, this isn’t to say that using morphology to help categorize species within a mushroom genus is useless or unimportant – just that it’s a tool within mycology, not an end-all, and that sometimes features don’t correspond to genetic sameness. And in the case of morels, DNA analysis both debunked some traditional categorizing while also (at least generally) upholding yellow and black types of morels, as these cap colors do tend to correspond with two distinct clades of morels. Below, we’ll cover each of the three clades in more detail.
Types of Morels: the Rufobrunnea Clade
The rufobrunnea clade currently contains only two species- the North American species, Morchella rufobrunnea (formerly known as Morchella deliciosa), and Morchella anatolica. This is the oldest clade of morels and likely originated in the Mediterranean Basin. We’ll discuss the North American species more in depth below.
M. rufobrunnea is among the few morels whose genetic distinction corresponds with specific morphological distinctions from most other morel species. The main morphological distinction of this species is that its cap and stipe bruises salmon pink-orangish to rusty brown. Bruising of fresh specimens is not known among any of the other currently described North American morels.
Unlike other species, the immature fruiting body cap of Morchella rufobrunnea is notably more twisted and pointed, often rounding with age. When young, the cap has dark grey pits and white-grey ridges. As the mushroom matures, the pits and ridges become more yellowish to brown-yellow. At maturity, the cap can reach almost 5 inches tall and 2 inches wide. The cap is fully attached to the stem. As with other true morels, the cap is hollow. Its spore print is pale yellow-orange.
The stipe of M. rufobrunnea can reach up to 3.5 inches tall and 1 inch wide. Sometimes this species displays a swollen base, but this isn’t consistent across all specimens. When young, the stipe color is often grayish, becoming more yellow to yellow-brown with age.
Ecology and Foraging
So, Morchella rufobrunnea is one of the only known morel species to be primarily saprobic rather than mycorrhizal (forming a complex, symbiotic plant-fungi nutrient exchange). As such, it is widely commercially cultivated and sold fresh and dried. As a saprobic mushroom, it derives its nutrients from dead organic matter.
Foragers often find this species of morel in disturbed areas such as along roadsides, trails, and landscaped sites. One of the earlier flushing true morels, you can usually find M. rufobrunnea in late winter through spring.
Types of Morels: the Esculenta Clade
The next clade of morels on our list is the esculenta clade, which currently contains five described North American species. Regarding types of morels, this clade is commonly known as the yellow morels and includes the prolific North American species, Morchella esculentoides, referred to commonly as the yellow morel. This clade likely originated in Asia before spreading to Europe and North America.
Yellow morels often have yellow to yellow-brown caps that vary widely in shape and have honey-comb like pits that are deep, wide, and randomly patterned. The ridges do not darken to brown or black with age, and the cap attaches to the stem without a notable groove. Caps can vary from fairly uniformly conical to squashed.
Below, we’ll cover the morphology and ecology of the widely distributed North American species, Morchella esculentoides.
The cap height at maturity of yellow morels can range widely from 4 to 8 inches, while it can reach about 2.5 inches wide. The cap shape of Morchella esculentoides is normally softly conical, though it can also appear more rounded. The honeycomb-like pits are typically irregularly arranged. The color and shape of the cap ridges can change dramatically with age.
When young, the ridges are often pale yellow to grayish, while the pits can be grayish-brown to charcoal-black. In this immature stage, foragers often describe morels in the esculenta clade as “greys”, with many guides describing them as a separate species. DNA analysis has confirmed that these “greys” are actually just immature yellow morels. However, an exception is in Western America, where a couple of species of the elata clade (black morels) are also referred to as greys,
When mature, the ridges of the cap are often white-yellow, yellow, or yellowish-brown, and the pits are usually yellow to yellowish-brown. As with other true morels, the stem and cap are hollow. The spore print is creamy to slightly yellow.
For this species of yellow morel, the stipe typically grows up to 5 inches high and 4 inches wide. However, the stipe can grow much larger in particularly warm, wet conditions and when left unpicked to age. Previously, specimens with distinctly large, inflated stipes were classified as a distinct yellow morel species. However, DNA analysis and observation of unpicked specimens confirmed that the existence of yellow morels with notably large stipes can occur across species.
The stipe of Morchella esculentoides is normally off-white to pale yellow or yellowish-brown and swollen at the base. The stipe is hollow, although when aged, the base of the stipe can become somewhat chambered.
Ecology and Foraging
Morchella esculentoides is a rather adaptable species of morel and may be both saprobic and mycorrhizal at various stages in its life cycle. Note that in mycology, as the understanding of fungi complexity grows, scientists are confirming more and more that many mushroom species can exhibit more than one type of plant/organic matter-fungi relationship (mycorrhizal, saprobic, parasitic) in their life cycles.
They are widely distributed across North America, and foragers can often find M. esculentoides growing under hardwoods, with a particular affinity for white ash and American elm. They are sometimes also found growing under conifers. M. esculentoides also seems to also have an affinity for apple trees as these delicious, highly sought-after morels often grow in abandoned apple orchards and under apple trees in urban settings.
The common time frame for finding M. esculentoides is March through June.
Types of Morels: the Elata Clade
The last of the three morel clades is the elata clade. This clade represents the black morels and includes species commonly known as “burn” or “burn-site” morels and “half-free” morels. This clade likely originated in Western North America. Currently, there are 14 described in the elata clade in North America. Remember, since we only have confirmed a small fraction of mushroom species in the world through DNA analysis, it’s important to understand that the number of species in a genus often changes as we understand more about the wonderful world of fungi.
Morels in the elata clade typically have characteristics such as caps with off-white to grey to charcoal-black ridges and similarly colored pits. However, black morels can also include species with caps that are off-white to grey, pinkish, yellowish, and greenish, especially when young. Unlike yellow morels, black morels typically have pits and ridges that darken with maturity and are primarily elongated and vertically arranged. Additionally, the cap of this morel is usually attached to the stipe via grooves.
Burn Morels in the Elata Clade
The 2011 genetic study of morels in North America took a look at burn morels, which are morel species known to appear (often in large flushes) in an area after a wildfire. All of these burn-site morels were confirmed to be a part of the elata clade. Typically, burn morels refer to morels that occur West of the Rockies, have a mycorrhizal relationship with conifers, and only flush after a fire.
Scientists are not sure exactly what triggers the mycelium of burn morels to fruit after a fire. Still, it likely involves the complex nutrient exchange between the morels and conifers, and changes that occur within this relationship and in the soil after a fire. In Western North America, there are currently four species in the elata clade known as burn morels: Morchella tomentosa, Morchella sextelata, Morchella capitata, and Morchella septimilata.
Half-Free Morels in the Elata Clade
Typically, a defining characteristic of true morels is their full attachment of the stipe to the pitted cap. However, the exception to this general rule is the half-free morels. These morels, such as Morchella semilibera, have caps that hang partially free over the sides of the stipe. While these morels are often typified into their own group due to their unique morphology, DNA evidence situates half-free morels into the elata clade. You might think of half-free and burn morels as sub-types in the elata clade.
The most widely distributed morel of the elata clade in North America is Morchella angusticeps. Below, we’ll cover the characteristics of the choice edible black morel.
At maturity, the cap of this black morel grows up to about 3 inches high and about 2 inches wide. As is common with black morels, the cap is typically conical, and the pits are elongated and arranged vertically. When Morchella angusticeps is young, the ridges are usually tan to brown, and the pits are often light brown to brownish-yellow. As this morel species matures, the ridges darken (as is common with black morels) to dark brown to black. Sometimes, the ridges of the cap turn an olive-green color, which some people refer to as “greenies” or “pickles.” The pits become a deeper brown to brownish-yellow.
The stipe of this morel usually grows about 3 inches high and 1 inch wide. The base of the stipe is sometimes slightly swollen and, often in warm, humid conditions, can develop grooves and folds along the base. Like other true morels, the stipe is hollow.
Ecology and Foraging
Like some other species of morel, Morchella angusticeps may be saprobic at some points in its life cycle in addition to forming mycorrhizal relationships with various plant hosts. This species of black morel tends to have an affinity for growing near hardwood trees such as white ash, green ash, and tulip.
Morchella angusticeps is widely found throughout Eastern North America. Foragers can find it growing alone or in groups from March through May.
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