Glossary of Mycological Terms

by Michael Kuo

Adnate, Adnexed . . . see Gill Attachment

Amyloid . . . see Using a Microscope: Viewing and Measuring Spores

A ring of tissue around the upper part of a mushroom's stem, resulting from the collapsing of the partial veil. Rings are extremely variable, ranging from ephemeral and quickly disintegrating to sturdy and prominent.

The type of ring a mushroom has is frequently a key determiner of its identity. Some mushrooms, like the Parasol Mushroom, have rings which are separable from the stem and can be made to slide up and down. The shape of a ring can also help identify some mushrooms; rings may be sheathlike ("peronate"), skirtlike ("pendant"), or intermediate. Additionally, the position of the ring can be important; it may be superior, apical, median, inferior, or basal ("at the very top" to "at the very bottom," in order).

Rings are notoriously absent when they should be present, so be sure to have both mature and immature specimens on hand when attempting difficult identifications; the partial veil will show up more clearly with immature specimens.

Cracked in age, like many of us. The cap surface of just about any mushroom can become cracked in dry weather conditions, but some species typically develop cracked caps in normal weather conditions. Boletus chrysenteron is an example. Often the color of the flesh, revealed between the cracks of an areolate cap, is an important identification feature.

Because the "crackedness" of a mushroom's cap is so dependent on environmental conditions, I do not recommend stressing it in your identification decisions--especially among the boletes, which are notorious for cracking up when they shouldn't. What they think is so damned funny is beyond me . . .

The Ascomycetes are fungi that produce their spores in little tubes called "asci" (the singular is "ascus"). The tubes are located on the spore-bearing surface of the mushroom. Thousands and thousands of fungi belong to the Ascomycetes, but most of them are not "mushrooms" as we mushroom hunters think of them. However, the morels, false morels, many cup fungi, and species of Helvella and Hypomyces are "ascos."

Asci cannot be seen with the naked eye, of course, so if you are wondering whether your mushroom is an Ascomycete or not, you will need a microscope to be sure. However, there are no mushrooms with gills, pores, or spore-bearing spines among the ascos--and the morels, false morels, and species of Helvella are fairly easily recognized--so the dilemma is not likely to come up unless you are trying to identify a cup fungus of some kind.

See also Ascomycetes, Mushroom Taxonomy, and Using a Microscope.

Basidia cannot be seen with the naked eye. They cover the gills of gilled mushrooms, and the interior surfaces of the tubes in mushrooms with pores. A basidium has tiny spore-holding prongs, called "sterigmata," on its end. Typically a mushroom's basidia hold two or four spores each, and this fact is often an important taxonomic feature (at other times it apparently is not, as in the case of the Destroying Angel).

See also Basidiomycetes, Mushroom Taxonomy, and Using a Microscope.

Boletinoid . . . see Pore Surface

A form of partial veil consisting of a cobweb-like protective covering over the immature spore bearing surfaces. The cortina is often very difficult to see; make sure you are examining very young specimens, and use a hand lens!

Cortinas typically disintegrate as the mushroom matures, disappearing entirely or leaving a ring zone on the stem. The genus Cortinarius, the largest genus in North America, is so named because its members typically have a cortina when young.

See also Using a Microscope.

Decurrent . . . see Gill Attachment

Dextrinoid . . . see Using a Microscope: Viewing and Measuring Spores

Some Chanterelles and Trumpets feature "false gills" on the underside of the cap, and separating this feature from true gills can be confusing for beginning mushroom identifiers. I recommend buying the common Button Mushroom (Agaricus bisporus) found in grocery stores, which has true gills, and torturing a specimen or two with a toothpick or knife point; you will soon discover that true gills are individual, plate-like or blade-like things, structurally separate from one another and from the flesh of the cap and the stem. The false gills on chanterelles, by comparison, are not structurally distinct units, and represent mere folds in the mushroom's under surface. Assessing "true" or "false" gills is especially important if one wants to eat chanterelles, since the poisonous Jack O'Lantern Mushroom is a look-alike with true, rather than false, gills.

Gills, known as "lamellae" in Mycologese, are platelike structures arranged on the underside of a mushroom's cap. The common Button Mushroom sold in grocery stores is a gilled mushroom, though it is usually sold in the button stage when the partial veil is still covering the gills. Gills are covered with microscopic basidia, which hold the mushroom's spores.

Close observation of the gills is one of the most important steps in identifying gilled mushrooms. Their colors are important, and may change as the mushroom matures. Whether or not the gills bruise when injured can be crucial to identification of a mushroom; use a knife point to damage the gills, and be sure to wait several minutes (sometimes even longer) for color changes. Many mushrooms have gills that discolor, or become spotted or mottled in age.

Gill Spacing

Whether a mushroom's gills are packed together tightly or have large spaces between them can be an important identifying feature. The official mycological terms to represent gill spacing are "distant," "subdistant" (meaning "nearly distant"), "close," and "crowded." Admittedly, one needs to have seen lots of mushrooms' gills to decide which of these terms best applies--and the gill spacing is of course proportional to the size of the mushroom. Enlarge the illustration to the right to see examples. I have found that subtle differences in gill spacing are fairly common, and it helps me to think of a six-point scale (adding in the fact that mushroom descriptions sometimes use a word like "very" in front of "distant" or "crowded"): very distant, distant, nearly distant, close, crowded, very crowded. If my mushroom's gills are off by one point on the scale when compared to a mushroom description, I do not let it bother me. If the gills are off by two or more points on the scale, however, I am likely to look for other identification possibilities.

How a mushroom's gills are attached to the stem can be an important identifying feature. However, in my opinion, mushroom authors often place too much importance on this feature, emphasizing subtle differences that are often quite variable in nature. The two extremes of the gill attachment scale are "free" (gills not touching the stem) and "decurrent" (gills running down the stem). You are not likely to find a mushroom that should have free gills demonstrating decurrent ones, or vice-versa. But the large middle range of the scale is confusing and, in my opinion, probably over-emphasized by mushroom authors. At MushroomExpert.Com, this entire range of the scale is referred to as "attached to the stem." Occasionally the means of attachment is fairly distinctive (for example, the "notched" gills of many Tricholoma species), but the subtle differences between "adnate," "adnexed," and so on, are often variable and rarely if ever crucial to identifying a mushroom to species (these subtle differences sometimes play a role in identifying a mushroom's genus, but there are almost always plenty of other features to consider). Most field guides contain illustrations of gill attachment possibilities. For a five-point scale (as opposed to the three-point scale used at MushroomExpert.Com) see Arora (1986, p. 17), and for a very thorough nine-point scale, see Smith, Smith & Weber (1979, p. 5). The References Page has full citations for these works.

Short-Gills (Lamellulae)

"Lamellulae," in Mycologese, are the short-gills that do not extend all the way from the cap margin to the stem. The presence or absence of short-gills is sometimes important in identifying mushrooms, as is the arrangement of the short-gills (randomly, in tiers, only occurring near the cap margin, and so on).

Marginate Gills

Gills are said to be "marginate" when their edges are colored differently than their faces. See the illustration to the right for an example.

Forking

Whether a mushroom's gills fork can be an important identifying feature; for example, Russula variata has a cap that is so variable in color that it cannot be identified on the basis of color--but its frequently forking gills separate it from most other species of Russula.

Gill Spacing
(click to enlarge)

Marginate Gills

Short-Gills

Forking Gills

Glandular dots appear on the stems of some mushrooms, mostly in the genus Suillus. The dots are usually very small, and result from clusters of pigmented, inflated cells on the stem surface. Identifying Suillus species often hinges on the presence or absence of glandular dots--but this can be a frustrating character to assess, since many species have whitish or pale glandular dots that do not darken and become conspicuous until maturity, or when the mushroom is dried. Glandular dots result from clustered caulocystidia (inflated cells) on the stem surface; for further discussion and an illustration of glandular dots at the microscopic level, see Suillus neoalbidipes. Bolete beginners should compare glandular dots with scabers, which are found in the genus Leccinum.

For a more extended discussion of this term, see the Lawnmower's Mushroom.

Click to enlarge!

The spore-bearing surface of a mushroom is called the "hymenium" in Mycologese. The gills constitute the hymenium of gilled mushrooms; tubes make up the hymenium of a mushroom with pores. In the morels, false morels and similar mushrooms, the hymenium is the cap surface. The hymenium is covered with microscopic asci or basidia, which hold spores until they are released.

Inamyloid . . . see Using a Microscope: Viewing and Measuring Spores

Lamellae, Lamellulae . . . see Gills

A "mushroom" is actually only the reproductive part of the organism--in the way an apple is only the fruit of the whole organism, the apple tree. The main part of a mushroom is underground or running through dead wood, and consists of a web or mat of hairlike fibers called a "mycelium" (the plural is "mycelia"). The mycelium is present even when there are no mushrooms. Some mushrooms, like the Honey Mushroom, have mycelia that stretch for miles and miles; you may remember the recent discovery through DNA testing of the "world's largest organism," a honey mushroom in the Pacific Northwest.

Basal Mycelium & Rhizomorphs

Evidence of the mycelium is sometimes found at the base of a mushroom's stem; there may be mycelial down or fuzz where the stem meets the ground. The presence or absence of basal mycelium is sometimes important in the identification process, as is its color. Mycelial cords or strands, called "rhizomorphs," are found in some species, and their presence often helps in identification decisions.

To view the basal mycelium of a mushroom you must be sure to include the stem base when you pick it--and digging around in the substrate with a pocket knife is often necessary to find rhizomorphs.

Basal Mycelium

Rhizomorphs

Click images to enlarge

Mushrooms that are mycorrhizal are involved in a symbiotic (mutually beneficial) relationship with the tiny rootlets of plants--usually trees. The cells of the mushroom's mycelium surround the tree rootlets with a sheath, and the mushroom helps the tree absorb water and nutrients while the tree provides sugars and amino acids to the mushroom. The organisms may need each other to survive. It is estimated that about 85% of plants depend on mycorrhizal relationships with fungi (Kirk et al., 2001; Dictionary of the Fungi). Many mushrooms are mycorrhizal with plants, including most Amanitas and Russulas.

Mushrooms that are parasitic consume the living tissues of other organisms, sometimes killing them in the process. Parasitism is fairly common among mushrooms, and is most famously demonstrated in Boletus parasiticus, which attacks the fungus Scleroderma citrinum. Other parasites include species of Hypomyces, which parasitize mushrooms, and the Honey Mushroom, which attacks trees and is a constant concern in forest management.

A partial veil is a covering over the gills or pores of young, button mushrooms, serving to protect the spore bearing surfaces until the spores have matured. The partial veil may take the form of a flimsy tissue which peels away as the mushroom matures, either disappearing or collapsing around the stem to form a ring--or it may take the form of a cortina, a cobwebby covering that later disappears or creates a ring zone on the stem.

Details of the still-attached partial veil are sometimes important in mushroom identification (for example, determining whether there are brown droplets on the veil to separate Agaricus placomyces from Agaricus pocillator), but it is what happens to the partial veil after it has peeled away that is more often important.

Partial Veil Remnants

Independent of whether the partial veil leaves evidence of itself on the mushroom's stem as a ring or cortina, it may also leave fragments clinging to the margin of the cap. Sometimes, these partial veil remnants are the only evidence one has that there was ever a partial veil at all, and their presence or absence is frequently important in mushroom identification. The bottom mushroom in the illustration shows partial veil remnants clinging to the cap margin of Psathyrella candolleana.

See also Universal Veil

Click to enlarge

Fragments of universal veil tissue left on the cap of a mushroom after it has matured are called "patches." Patches are similar to warts, but there are fewer of them, and they typically involve larger fragments, as in the illustration to the right. Like warts, patches are easily washed off by rain, making them a difficult feature to be sure of.

Pileus = The cap of a mushroom

Pores on mushrooms are tiny holes, just as they are with skin. Many mushrooms (namely, the boletes and polypores) produce their spores on the inside surfaces of tubes. Imagine the cardboard tube from a roll of paper towels, with the inside of the tube covered with seeds. Then pack many such tubes together, side by side, and turn the whole thing sideways. You are now looking at the ends of the tubes--some very large "pores." This is essentially how mushrooms with pores arrange things, though the seeds (spores) are microscopic. They are held on microscopic basida until they flip off of their holders and plummet down the tubes to meet air currents.

Observation of the pore surface, on the underside of the mushroom's cap, is often important in mushroom identification. The size of the pores (usually expressed as a number of pores per millimeter) can be important, as well as their arrangement. Often the tiny holes make no particular pattern, but in some cases they are clearly elongated and radially arranged, especially near the stem. Pores like this, in Mycologese, are called "boletinoid." In some cases pores are so boletinoid that they begin to form ridges near the stem and can approximate the appearance of gills; this kind of arrangement is called "lamellate."

The color of a mushroom's pore surface can be crucial to identifying it--but the color is frequently subject to change as the mushroom develops. When identifying boletes, therefore, it is often necessary to have collected mushrooms in both "button" and mature stages. Whether the pore surface bruises is also an important feature; scratch the pore surface with the tip of a knife to see any color changes.

Tubes

The depth of the tubes is often cited by mushroom authors--but do not forget that this feature will vary according to the mushroom's maturity.

Bruising Pore Surface

Boletinoid Pore Surface

Something is "reticulate" when it has a network of raised ridges that create a net-like pattern, like the stem of the bolete shown to the right. Reticulation is a texture, and not necessarily a color difference. Often, the raised ridges on a reticulate stem are colored differently (or eventually discolor), but this is not always the case. For an explanation of reticulation on the stems of boletes, see the page for Boletus illudens.

Spores of some mushrooms may also be "reticulate" or "partially reticulate"-- but, of course, a microscope is needed to see the reticulation.

The word "reticulum" is a noun referring to the network pattern itself--for example, "stem with a raised reticulum that darkens on handling."

Reticulate stem

Partially reticulate spores

Rhizomorphs . . . see Mycelium

Ring . . . see Annulus

A "ring zone" is a zone on the upper stem of a mushroom resulting from the deterioration of the partial veil. Ring zones are frequently not as prominent as the rust-colored zone on the Cortinarius species illustrated to the right; they may be barely noticeable. Use a hand lens if you are unsure! The ring zone may be the result of a tissue-like partial veil, or it may result from a cortina. In my experience, mushrooms that are "supposed to" have ring zones frequently do not, even when a hand lens is used--all the more reason to have both mature and immature specimens available when attempting a difficult identification, since the partial veil will be more easily seen on buttons.

Mushrooms that are saprobes survive by decomposing dead or decaying organic material. Many wood rotting fungi are saprobes, and help decompose dead wood--but other wood rotters are parasitic and attack living wood. Most yard and garden mushrooms (like Marasmius oreades) are saprobes, as well as dung-loving mushrooms and mushrooms that decompose leaf or needle litter (like Marasmius pulcherripes).

Scabers are little scurfy things that stick up, like the scabers on the stems of Leccinum mushrooms, shown to the right. "Scabrous": having scabers. Compare with Glandular Dots, which are found in the genus Suillus.

Spores are "seeds," more or less, unless you want to study mycology. They are microscopic, and are produced either in asci or on basidia, depending on the mushroom; these microscopic structures are found on the spore-bearing surface of the mushroom (called the "hymenium" in Mycologese)--for example, the gills or pores.

Observation of a mushroom's spores is one of the most important steps in the identification process. Obviously, a microscope is needed to view spores individually, measure them, and record their distinctive features. But the color of the spores, when seen in mass, is also important, and a microscope is not required. See our page on Making Spore Prints for simple instructions.

Determining the color reaction of spores to Melzer's reagent is also sometimes important in identifying mushrooms; see the page on Using a Microscope: Viewing and Measuring Spores for further information.

See also Using a Microscope

Spore Print

Stipe = The stem of a mushroom

Sub (insert word) = "Almost" or "nearly" (insert word)

Subdistant . . . see Gill Attachment

Tubes . . . see Pores

A "universal veil" is a tissue enclosing the entire button mushroom. It serves to protect the immature mushroom, and makes it look rather like an egg. When sliced in cross-section, button mushrooms encased in universal veils reveal the mushroom-to-be inside (which is why those who eat puffballs should always slice them open to make sure they are not poisonous Amanitas!). The universal veil is ruptured by the growing mushroom, and it may disappear entirely or leave warts or patches on the cap of the mature mushroom--and/or fragments at the base of the stem.

Many mushrooms display a universal veil, including Amanita species like Amanita muscaria, Volvariella species, and stinkhorns.

See also Partial Veil

Click to enlarge

A "volva" is a ruptured, sack-like covering at the base of the mushroom's stem. The volva results from the mushroom pushing through the universal veil, which covers young buttons to protect them. Many species of Amanita, including some of the deadliest mushrooms on earth, have volvas, as do mushrooms in Volvariella and some other mushrooms.

Because the deadly Amanitas have volvas, it is essential for beginning mushroomers to learn how to recognize this feature. Sometimes volvas are buried, and they are not always as prominent as they are in a typical Amanita phalloides or Volvariella speciosa--so you should be sure to dig out the base of the mushroom in question and inspect it carefully!

"Warts" are pieces of tissue adorning a mushroom's cap, resulting from the deterioration of a universal veil. Warts are similar to patches, but there are more of them. They may be densely arranged, as in the illustration to the right, or more sparsely distributed. Warts are also frequently washed off with rain, making them a difficult feature to be sure of.

Cite this page as:

Kuo, M. (2006, February). Glossary of mycological terms Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/glossary.html

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