CHAPTER XXI 



MUSHROOMS AND TOADSTOOLS 



Family 8. Agaricace^. — The mycelium of the fungi of this fam- 

 ily lives in the substratum, which may be the soil, leaf mould, rotten 

 wood, old stumps, dead tree trunks, or living trees, as far as the natural 

 environment is concerned, and in manures, in the decay of agricultural 

 plants in the fields, offal, spent tan bark and rubbish heaps, as far as 

 man has influenced the environment. The hyphse may be delicate and 

 cobwebby, thread-Uke, cord-like, or in strands (rhizomorphs) . They 

 are always septate, sometimes with clamp connections and their color 

 may vary from white to yellow, or brown {Armillaria mellea). The 

 fruit bodies are mostly fleshy, rarely of membranous, or leathery, con- 

 sistency. Usually of an umbelloid form, they may have a sessile cap, 

 or pileus, or the stalk, if present, may be attached laterally, although 

 it is placed centrally as a general rule. The hymenophore consists of 

 radiately arranged veins, folds, or gills (lamellae), which are generally 

 free from each other, seldom anastomosing, or dichotomously branched. 

 As the popular name toadstool is suggestive of the commonest form 

 of these fleshy fungi, a few words of explanation with regard to the 

 general structure will be apropos. Attached to the spreading myce- 

 lium we find arising vertically the stalk, or stipe. The height of this 

 varies in the different genera and species. Sometimes it is enlarged 

 at the base, at other times, the stalk is perfectly cylindric. The sur- 

 face of the stipe may be smooth, rough, reticulate, or stringy, and its 

 center may be solid, stuffed, or hollow, as the case may be. An annu- 

 lus, such as is present in the common mushroom, may in other forms 

 be absent, or well developed. Placed on the stem, or stipe, above we 

 find the cap, or pileus, which is expanded horizontally. It has a 

 domed, convex upper surface sometimes with a projecting boss, or 

 umbo; in other forms it is depressed (crateriform, umbilicate, etc.). 

 The gills, or lamellae, are attached to the lower surface of the pileus. 

 They may run from the stipe to the margin, or they may run only 

 part way, so that frequently there are secondary gills alternating with 



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