What's the Stem of a Mushroom Called, Stalk or Stipe--Fungal Biology
- Mar 22
- 4 min read
Updated: 5 days ago
A mushroom is just a mushroom, right? Nothing else besides what meets the eye? (Spoiler: NO). And what do you call the 'thing', for lack of a better term, that holds up the cap? A stem? A stalk? Well, all those questions and more will be answered in this blog! If you're going to read my other blog posts, I would really recommend you start with this one to better understand the terminology I will use (although I will try my best to define relatively new or difficult terms).
So...What Are Fungi?
For a really long time (centuries, to be specific), fungi were classified as plants. But as any mycophile (myco for mushrooms, phile for lover/fondness) will ardently tell you that fungi are their own distinct kingdom of organisms distinct from plants, animals, and bacteria. You'll most likely find them on a tree, in your house in the form of molds, or just anything woody: (can digest lignin, the tough, structural polymer in plant cell walls).
Unlike plants, fungi do not perform photosynthesis (Boring! Who said that?); instead, they obtain nutrients through absorption. Another way they differ from plants is their cell wall composition: plants contain cellulose to give you a hard time when you eat salad, and fungi contain the carbohydrate chitin so they can push through asphalt! (Yes, you read that right, pavement mushrooms such as Agaricus bitorquis and puffballs can push through asphalt using intense turgor pressure). Plants and fungi do have similarities, though–both are eukaryotic (their cells contain a nucleus), and most fungi are sessile (immoble), like plants. In addition, they often form complex symbiotic relationships with each other or even with a third partner! (Lichens; cough, cough).
The most widespread misconception I encounter is the assumption that, for lack of a better description, is that a mushroom is just a mushroom. That's like saying a tree is just a piece of fruit! Even when a mushroom dies, the mycelium (network underneath it) still survives. The mushroom is just a reproductive structure that pops above ground for a little while. Fungi can also grow on dung or wood too, but they still have mycelium! It's often soil growing mushrooms, however, that form complex networks underground with other plants and fungi, but that's a blog post for another day.
The Structure of Fungi
Fungi can be unicellular, like yeast (which make bread and wine for my foodies), or multicellular, like our good old mushrooms. Just like any other organism, they are made up of lots of different parts like:
Hyphae: Thread-like structures that make up the body of a fungus. They can be septate (divided by walls) or coenocytic (without walls).
Mycelium: The "roots" of a mushroom made up of a network of hyphae that is often found underground or within its food source. It's great for packaging!
Cap (Pileus): The top, umbrella-like portion that protects the spore-producing surface underneath. We call it the pileus, because (believe it or not), not all fungi have a cap.
Gills (Lamellae): Thin structures under the cap that produce and release microscopic spores, which act as the "seeds" for new fungi. Some mushrooms have pores, teeth, or ridges instead of gills, but that's a whole different post.
Stem (Stipe): The stalk that supports the cap and lifts it above the ground to better disperse spores into the wind.
Ring (Annulus): A skirt-like ring of tissue around the stipe. It's the remnant of a partial veil that protected the gills while the mushroom was young.
Volva: A cup-like structure at the very base of the stem. This is the remnant of a universal veil that completely enclosed the immature mushroom (I know, a lot of remants).
Scales: Patchy remnants of the universal veil that sometimes remain on top of the cap, like those on your classic red and white mushroom, the fly agaric.
Types of Fungi
19 phyla have been proposed to represent the full diversity of fungi, but, for the sake of readability, let's just stick with the generally used seven. The two you'll really want to remember are sac fungi and club fungi; they come up a lot (both on walks and in future blog posts!).
Ascomycota (Sac Fungi)
The largest phylum of fungi, including yeasts, molds, and morels. They reproduce sexually through the formation of ascospores in a sac-like structure called an ascus (hence the name sac fungi)!
Basidiomycota (Club Fungi)
Your phyla if you're looking for your stereotypical mushroom, puffballs, and shelf fungi. They reproduce sexually through basidiospores formed on a club-shaped structure called a basidium.
Zygomycota (Conjugated Fungi)
These fungi are primarily terrestrial and often found on decaying plant and animal matter. They reproduce sexually by forming zygospores.
Glomeromycota
These fungi form symbiotic relationships with plant roots, known as arbuscular mycorrhizae, which help plants absorb nutrients from the soil.
Chytridiomycota (Chytrids)
Chytrids are mostly aquatic fungi and are known for their flagellated spores. They're the decomposers in aquatic environments.
Neocallimastigomycota
Anaerobic (oxygen-absent) fungi found in the digestive tracts of herbivorous mammals (think cows and sheep). Here's a fact to tell all your friends: they produce enzymes that break down the tough cellulose in the grass the animals eat.
Blastocladiomycota
Similar to Chytrids, these live in water or soil and have spores that swim! They were once grouped with Chytrids, but are now their own phylum because they exhibit a specific type of "alternation of generations" (switching between two different life stages).
Hopefully, after reading this, you've realized how diverse and complex fungi really are (and you have something to drone on about at dinner). Next time you spot a fungus on a hike, take a closer look and, although you are a large, lumbering human, try to appreciate the fragile beauty that keeps our ecosystems alive.
(If you enjoyed this article, it would be great if you could share Morel of the Story with a friend!)
Bibliography
“Fungus - Mycorrhiza | Britannica.” Encyclopædia Britannica, 2019, www.britannica.com/science/fungus/Mycorrhiza.
S, Danny. “Parts of a Mushroom: A Detailed Guide to the Anatomy of Fungi.” Feral Fungi, 7 Apr. 2023, feralfungi.com/blogs/news/parts-of-a-mushroom?srsltid=AfmBOooh6gvlkCaT4bXd2HuZ87ncyMyTM7wqoZZtDcfjxw5UES1a973m. Accessed 29 Mar. 2026.