Identification and Terminology
The
uncompromising “toadstool” taxonomist will always bring his mushrooms home in
pristine condition. Tender care should be given to each specimen in the field
and on the way home. In other words handle each mushroom with care, make sure
not to move the specimens from one container to another unnecessarily and do not
leave them in unventilated places like your car for extended periods of time.
Identification of each species should always be conducted on fresh specimens and
if at all possible the day they are collected. The reason for the “rush” is
that many species quickly lose their original color and / or are consumed over
night by maggots that have infested them prior to you collecting them.
Furthermore, Coprinus species autodigest (self-digestion) in a few hours,
leaving behind little more than a stalk and remnants of the cap covered in a
black ink (Arora, 14).
Identification of fungi involves both macroscopic and microscopic characteristics. Each set of characteristics has its own terminology that at first glance may appear somewhat overwhelming. However, with a little determination and repeated exposure to the descriptive terminology used of macroscopic and microscopic characteristics, field guides and their dichotomous keys will become easier to use with time. Listed below is the basic terminology used for identifying and describing gilled mushrooms. Fungi that have fruiting bodies with a significantly different structure are illustrated and discussed in their section on this website (Arora, 14).
Macroscopic Characteristics
1. Size is dependent on the following three factors: age, amount of moisture available, and genes. Fungi that fruit during rainy periods tend on average to be larger than those that fruit during dry intervals. The terms large, medium, small, and minute are often used in describing the size of various structures. When measurements are given they represent average size ranges. Measurements are given most often using the metric system (Arora, 14).
2.
Color
is probably the first characteristic noticed of a fungus. However, it is
possibly the most misleading and variable characteristic used in describing the
features of a mushroom. The deceptive nature of color stems from environmental
influences and age. For instance, direct sunlight and prolong periods of rain
tend to significantly bleach mushrooms. Similarly, the particular color of
certain species of fungi change as the species matures. Hygrocybe conica while immature may be red, orange, or yellow, but as it ages it blackens. The
stalk of most mushrooms is not as variable in color as the cap. This is because
the cap shelters the stalk from sunlight and rain. On the other hand, gill
color may change as the spores mature (Arora, 14).
3. Color Changes can take place when mushrooms are bruised. These color changes can occur rapidly to very slowly and anywhere in between. Look for color changes (bruising reactions) on the surface of the cap, gills, stalk, and the cut flesh inside the cap and stalk (Arora, 15).
4. Texture can be a significant characteristic. Standard descriptions of texture include soft, watery, spongy, brittle, tough, leather, corky, and woody (Arora, 15).
5. Odor and Taste are basically chemical tests conducted in the “laboratories” of the mouth and nose. Not all “laboratories” are created equal and as a result one mushroom may smell a particular way to one individual and completely different to another. To complicate matters, when mushrooms are crushed their odor may change dramatically, for example from mild to pungent. Similarly, waterlogged mushrooms may become totally odorless. When tasting a mushroom only a small piece of the cap should be sampled and then spit out. It is a good policy to never taste unknown mushrooms, in particular Amanitas. Tasting should only be done when called for in classification keys (Arora, 15).
6. Cap – The cap is the structure of the fruiting body that supports the spore-producing surface. The cuticle is the skin of the cap and may be referred to as the pellicle if it peels away easily. The following terms are used to describe the appearance and texture of a cap (Arora, 15):
Additional features about the cap to note are its size, color and color changes, shape, surface texture, and the appearance of the margin (Arora, 16)
7. Flesh descriptions include comments about color, color change, texture, thickness, odor, and taste (never swallow test sample) (Arora, 16)
8. Gills or lamellae are the spore-producing blades on the underside of an agaric (Arora, 1986, 915). Characteristics of importance include how the gills are attached to the stalk, their spacing, thickness, depth, forking pattern, and color (Arora, 16).
9. Stalks are the stemlike structures that support the cap in most mushrooms (Arora, 1986, 917) and serve to force the cap up through the substrate so the spores can be discharged into the air. Characteristics to note include: size, color, color changes, shape, position, texture, surface characteristics, viscidity, and the presence or absence of an annulus or volva (Arora, 16).
10.
A Veil is a protective layer of specialized tissue that initially
shields the developing mushroom that eventually breaks up or disintegrates with
time. Two basic types of veils exist: partial and universal (Arora, 16).
Partial veils stretch from the stalk to the cap margin in many young mushrooms
(Arora, 916). As a result, mushrooms with partial veils have their gills
or pores covered until the veil breaks. Universal veils envelope all or most of
the young fruiting body of particular mushrooms (Arora, 918).
Occasionally, universal veils will form a volva once they break (Arora, 16). The following terms are often used in describing particular attributes of
veils:
a. persistent – leaves visible remnants on the cap and /or stalk after breaking
b. evanescent – disappears; only detected in button stage
c. membranous – skinlike and usually persistent
d. fibrillose – hairy, disappears or forms a belt of collapsed hairs on the stalk
e. cortina – cobwebby and fibrillose
f. glutinous – slimy and either evanescent or leaves a layer of slime on the stalk and/or cap (Arora, 16).
11.
An Annulus (ring or collar) may form on the stalk after a veil
ruptures (Arora, 913).
If this is the case you should note its color,
texture, shape, and position on the stalk (Arora, 16).
12.
A Volva may form at the base of various mushrooms that have well
developed universal veils. When the veil breaks open it leaves visible remains
(that is a volva) at the base of the stalk. Amanita species are
probably
the most well known mushrooms that develop a volva (Arora, 18).
Amanita have four different types of volvas: saclike, collarlike, scaly and
indistinct (Arora, 264). Similarly, stinkhorns and certain stalked
puffballs also produce a volva. Small patches of the universal veil that adhere
to the cap after it ruptures are called warts (Arora, 18).
13.
Mycelium
is the vegetative portion of the fungus and is typically hidden from view given
that it usually grows underground or within another substrate. However, careful
inspection of the
forest humus will more often than not reveal abundant mycelial
threads. In and of themselves mycelial threads provide very few clues as to the
species of mushroom that produced them. Some exceptions do exist as is the case
with Chlorociboria aeruginascens, an ascomycete that stains its
substrate (wood) bluish-green (Arora, 18). One important feature that may
aid in identification is the color of the mycelial threads.
14. Spore Color and Spore Prints are extremely useful characteristics to use when trying to identify gilled mushrooms. Spore color is not as susceptible to environmental influences as compared to the fruiting body of the same mushroom. Hence, the colors of spores are relatively constant over time. Probably the most reliable way of determining spore color is by making a spore print. Spore prints should be made with fresh, mature specimens to obtain the best results possible. To make a spore print simply cut off the cap of a fresh, mature mushroom and lay it gills down on a white piece of paper. Cover the cap with a box, bowl, cup, etc. in order to protect the spores from air currents. Usually within 2-6 hours a spore print will have formed on the paper. In addition to gilled mushrooms, spore prints can be made from boletes, chanterelles, coral fungi, teeth fungi, and occasionally polypores (Arora, 18). Spore colors are traditionally separated into several broad categories (pink spores, brown spores, etc.) and at first glance seem rather straight forward in their meaning. However, assigning a spore print to the correct color designation can be rather tricky for the inexperienced collector. The difficulty in assigning the correct color description to a particular spore print is two fold. First, the color categories are not as they “appear”. For example, “pink” is closer to flesh color than to bright pink as one might expect. Secondly, the thickness of the spore print and moisture content can also affect the color. Not to worry though, with enough practice and comparison just about anyone can learn to evaluate the color of a spore print correctly (Arora, 19).
Microscopic Characteristics
Microscopic characteristics can and do play a very important role in the identification of certain species of fungi. Clearly, you must have a microscope in order to use microscopic features. Probably the most common microscopic feature noted in field guides, keys, etc. are spore characteristics. Typically, the shape, size, and ornamentation of the spores are listed for each species (Arora, 19). Spores can be observed by using spore dust to make a wet-mount using a drop of water, microscope slide, and cover slip (Arora, 20.)
In addition to spore characteristics other microscopic features may be noted. However, even though these features are quite possibly more significant than spore characters, they are more difficult to observe. These include: orientation of the hyphae in the gill tissue, structure of the cap cuticle, and shape and size of cystidia (Arora, 20).
Chemical Characters
The use of chemicals and how mushrooms react to them play an important role in their classification. Two important chemicals that every serious collector / mushroom hunter should have are: KOH (5-10% aqueous solution of potassium hydroxide) and Meltzer’s reagent (an iodine solution). Spores that stain blue, gray, or black in Meltzer’s reagent are said to be amyloid. Spores that stain reddish-brown are dextrinoid. The easiest and most effective way of observing the possible color changes associated with Meltzer’s reagent is to use a microscope to view the spores (Arora, 20).
Works Cited
Arora, David. Mushrooms Demystified. 2nd ed. Berkley, Ten Speed Press, 1986.