On Thursday, March 20, around 25 Waltham residents, a small but eclectic crowd, gathered in the lecture hall of the Waltham Public Library for guest speaker Jonathan Kranz’s presentation on mushrooms. More specifically, the process of foraging, identifying and generally appreciating the fungal life forms that appear in the state of Massachusetts. 

Upon entering the lecture hall, participants’ attention was drawn to a table set up at the front of the room where Kranz had laid out a variety of dried mushrooms and spore prints. Spore prints, as Kranz explained, are an imprint of the spores dropped by a mushroom cap — kind of like the mushroom’s fingerprint. They reveal the shape of the mushroom’s spore-bearing surface as well as the color of its spores, both of which are important for identification. 

Before Kranz started his presentation, he briefly introduced himself and shared his credentials. Kranz is a Mass Audubon certified naturalist, Vice President of the Boston Mycological Club and board member of the Pioneer Valley Mycological Association. The BMC, as Kranz noted, is the oldest mushroom club in North America. 

Kranz, who often leads foraging walks for the BMC, began his presentation by broadly exploring what a mushroom actually is. He explained that the pictures on his slides, displaying several images of New England fungi, were all considered to be mushrooms despite their vast diversity in shapes and color. Though it is common to think of mushrooms as having a prototypical stem and cap, they actually have a lot of structural diversity. Kranz pointed out the black trumpet mushroom, a concave fungus that looks like a shriveled tube, and lion’s mane, a type of tooth fungus made of hundreds of small white filaments as well as several types of fungi that resemble corals. 

But the word “mushroom” doesn’t tell the whole story. As Kranz explained, the mushroom is just the above-ground fruiting body of a larger organism. Picking a mushroom is “like taking an apple off a tree,” as Kranz put it. Most of the fungus exists underground as vast networks of thin, white filaments called hyphae. Hyphae are microscopic, as each strand is the width of a single cell. When bunched together, these hyphae form mycelium, which are the thin white strands that are visible when digging through soil. 

While they may be tiny, these networks of mycelium are not to be underestimated, Kranz explained. Fungi have the ability to direct water pressure through their mycelia, allowing them to achieve the force necessary to penetrate hard surfaces. For example, any fungus growing on a tree contains mycelial networks which have managed to grow through several layers of bark and wood. Fungi have also been known to break other hard surfaces, like concrete.

Additionally, mushrooms are decomposers, beings that Kranz described as “inside-out” animals. He elaborated that when humans eat enzymes, the digestive system breaks down food into nutrients. Fungi, on the other hand, secrete digestive enzymes that break down the material around them, allowing them to absorb the nutrients they need from their environment. 

Kranz then elaborated on the nature of spores. Spores are the reproductive cells of fungi, and are released from the mushroom’s hymenium, or spore-bearing surface. Hymenia come in a variety of shapes, the most common being gills, which are the papery divisions found underneath a mushroom’s cap. Unlike seeds, spores are single-celled organisms and do not contain any nutrients for the hyphae that germinate from them. 

Mushrooms, as Kranz explained, have evolved a variety of methods to ensure that their spores spread. In most cases, spores are spread by the wind, just like the seeds of a dandelion. Some fungi, like truffles, have evolved structures that attract animals. In the case of truffles, it is their pungent odor that attracts animals to eat them. Other mushrooms, like stinkhorns, secrete pheromones that attract insects, which carry the spores onward. 

Kranz added that mushrooms often grow in a structure called a fairy ring, or a circle of mushrooms often found in meadow environments. The reason that mushrooms will sometimes grow in fairy rings is that the mycelium grows in a circular shape, originating from a central point. When the optimal growing conditions occur for that species of fungus, mushrooms will shoot out around the edges of the mycelium, creating a fairy ring. 

Kranz then described how he categorizes different types of fungi. Though fungi have many different characteristics that can be used to define them, he likes to use three main groups: parasitic, decomposer and ectomycorrhizal. 

Parasitic fungi, like all parasitic organisms, gain nutrients from a symbiotic relationship with another organism that actively benefits one party and actively harms the other. In the case of parasitic mushrooms, the fungus is benefited. An example of a parasitic fungus is the honey mushroom, which causes root rot in trees using structures called rhizomorphs. 

Decomposer fungi gain nutrients from breaking down organic matter. This organic material can include dead wood, dead leaves, excrement and several other natural substrates. These fungi are important to any ecosystem, as they allow for the return of nutrients to their local soil. Kranz emphasized that the ability of fungi to break down complex molecules is a natural miracle, on the same level as photosynthesis. “If life only had [photosynthesis], we would not have complex organisms,” he explained. 

Ectomycorrhizal fungi get their nutrients, at least in part, through mutually beneficial symbiotic partnerships with the nearby trees. Kranz broke down the word: “ecto” means exterior, “myco” indicates fungi and “rhizal” means related to roots. Ectomycorrhizal fungi wrap their hyphae around tree roots, he explained. The fungus delivers water and nutrients to the tree, and the tree gives it sugars in return. This relationship, Kranz explained, is why certain mushrooms like chanterelles and porcini are difficult to cultivate. As it turns out, complex symbiotic relationships are difficult to form artificially. 

Kranz then discussed some of the most common mushroom genera. He focused on specific mushrooms that appear in early spring, encouraging participants to keep an eye out for them as the weather warms. 

To start, Kranz delved into the genus Amanita, which includes some of the most well-known mushrooms. One of the unique aspects of the Amanita genus is how they develop. At the beginning of their lifecycle, Amanita form an egg-like structure called the “universal veil” around the immature mushroom body. Kranz modeled this structure by crouching down and forming an egg-like shape with his body. He then stood up to demonstrate how Amanita mushrooms break out of the universal veil, their cap spreading as they mature. Many Amanita have warts on their cap, which are remnants of the universal veil.

The fly agaric, well-known for looking similar to the power-ups found in the Mario franchise, is in the genus Amanita. Kranz was also sure to point out the destroying angel, a pure white Amanita that is deadly when ingested. They contain amatoxins, which inhibit the ability of ribonucleic acid, or RNA, to make protein. In other words, ingesting a destroying angel is fatal unless the victim gets immediate treatment. 

This information prompted one participant to ask if compounds from fungi have been used to make biological weapons. Kranz answered by recommending the movie “Wormwood,” which focuses on the life of a scientist who had been experimenting with such technology and was mysteriously found dead. 

Kranz then went over a few more common genera. Boletes are mushrooms that have pores instead of gills, and are almost always ectomycorrhizal. Russulas are smaller mushrooms that can be various shades of brown, green and red. He noted a red Russula called Russula emetica, or “the sickener.” As the name suggests, these are not safe to eat. Kranz also went over the genus Lactarius, which oozes latex when scratched. Finally, he discussed the genus Cortinarius, which will always have blood-red spores. 

After discussing common fungal genera, the focus of Kranz’s presentation pivoted to the applications of fungal knowledge. He started with the famous corpse of Otzi the Iceman, a 5,000-year-old preserved body found in Iceland. Otzi had two fungi on him: tinder polypore and birch polypore. Tinder polypore is known to be used as a firestarter and birch polypore is known for a general array of medicinal qualities. 

As Kranz addressed during an earlier portion of his presentation, he calls any mushroom that has been known to have medicinal qualities “alleged medicinal.” This title is not meant to disrespect any belief surrounding such fungi, but to acknowledge the possibilities of properties that have not yet been formally tested. 

He moved on to discussing mushrooms that one can find in New England during the appropriate season. In early spring, he explained foragers will find mostly platterful and deer mushrooms. Kranz called them the “lettuce of the mushroom world,” as they are edible but not tasty. Dryad’s saddle, on the other hand, is a beautifully patterned shelf mushroom that can be found in March and April. It is edible, and often found growing in tree stumps. 

In mid-July, chanterelles, prized edible mushrooms, start appearing. Kranz gave the audience tips on how to distinguish them: they often associate with deciduous trees, they will never grow in clusters and they pull apart like string cheese. He cautioned the audience not to confuse chanterelles with jack o’lantern mushrooms, which are toxic look-alikes. 

At the end of the summer, the bright orange chicken of the woods, a shelf fungus, will start growing on the sides of trees. When foraging this famous polypore, Kranz suggests that the audience only consider specimens with vibrant color and not grey color, which indicates the presence of bacteria.  

Kranz also covered the practical aspects of foraging for mushrooms. He suggested having a basket for minimal compression when collecting mushrooms, paper bags to further protect the mushrooms, a knife or weed-puller to fully extract mushrooms from the ground, a notebook and pen to keep track of the environment in which the mushrooms were found and a camera to take pictures of any fungi found. He noted that it is safe to handle all mushrooms, even toxic species, as they need to be ingested to cause harm. Additionally, it is important to cook every mushroom before consuming, as they could contain harmful bacteria. 

To conclude his presentation, Kranz demonstrated how to make spore prints. To make a spore print, Kranz explained, the cap of the mushroom must first be removed. Then, it is placed on an index card (or other paper-like surface) with its gills facing down and covered for four to 12 hours. If the cap is dry, adding a small amount of wet paper towel before covering will help release the spores. Over the time during which the cap is left covered, the spores will release from it, leaving an imprint of the mushroom on the index card. After the spore print has dried Kranz likes to fix his spore prints with cheap hair spray, which he says is just as effective and much less expensive than specialized fixative sprays. 

Following the presentation, Kranz shared some of his favorite mycology resources with attendants, including mushroomexpert.com, the YouTube channel “Learn Your Land” and various field guides. He also encouraged participants to join a local mushroom club such as the BMC if they were interested in learning more about foraging.