MUSHROOM 



cords small rounded bodies formed by the upward 

 growth of the threads of mycelium. These increase in 

 size and grow toward the surface of the ground. Each 

 one is the young stage, or button, of the Mushroom. As 

 it enlarges, the upper end appears as a round body on a 

 short stalk, thus outlining in the embryonic stage the 

 different parts of the mature plant. The gills are form- 

 ing on the under side of the cap. They are at this time 

 covered. They appear on the under side of the minute 

 constriction at the junction of the cap and stem. At 

 this stage they are covered by a loose growth of mycel- 

 ium extending from the upper part of the stem to the 

 margin of the cap. This forms the veil. The gills are 

 formed by mycelium growing downward on the under 

 side of the cap in radiating rows, thus forming the la- 

 mellae. The plant now continues to enlarge and the 

 cap expands. Just about maturity the veil ceases to 

 grow and the expanding cap thus stretches it until finally 

 the veil is ruptured, usually next the margin of the cap, 

 and then it hangs as a collar or ring on the stem (seen 

 at a, Fig. 1441). 



Position of Agaricus campestris in Classification. 

 One of the large subdivisions of the higher fungi is 

 made up of the Mushrooms, toadstools, puff-balls, etc. 

 All of these are characterized by a more or less well- 

 developed fruiting surface, or hymenium. The struc- 

 tural element of the hymenium is the basidium, and in 

 the large number of the species the form of the basidium 

 does not vary to any great extent from that of the com- 

 mon Mushroom. The basidium, then, is the character- 

 istic fruit structure of this large subdivision of the 

 fungi. For this reason, the plants included in this sub- 

 division are termed the Basidiomycetes . The Basidio- 

 mycetes, taken in the sense of the earlier students of 

 the fungi, were divided into two orders, according to 

 the condition of the fruiting surface at the maturity of 

 the plant, namely the Hymenomycetes and the Gaster- 

 omycetes. In the former, the fruiting surface is either 

 exposed from the beginning, or if covered at first, is at 

 last exposed before the maturity of the spores, just as 

 the hymenium of Agaricus campestris, at first covered 

 by the veil, is exposed before the maturity of the spores 

 .by the rupture of the veil. The Mushrooms, toadstools, 

 etc., belong, therefore, to the Hymenomycetes. In the 

 Gasteromycetes, on the other hand, the spores are ma- 

 tured before the hymenium is exposed, as in the puff- 

 ball, earth-star, etc., which open after the spores are 

 ripe. 



Families of the ffymenomycetes. The usage of the 

 earlier botanists in the arrangement of families will 

 be followed here, since there is not an opportunity to 

 properly set forth the principles of classification adopted 

 by some recent systematic works. The arrangement 

 depends on the character of the fruiting surface or 

 hymenium. 



A. Fruiting surface uneven; i. e., in the form of plates, 

 tubes or spinous processes. 



1. Agaricacese, fruiting surface in the form of plates 



or gills. 



2. Polyporaceae, fruiting surface in the form of pores 



or tubes. v 



3. Hydnacege, fruiting surface in the form of spinous 



or tubercular processes. 



AA. Fruiting surface even; i. e., not as in A, except in 

 the case of plants of a gelatinous texture. 



4. Clavariaceae, plants more or less erect, standing 



out from the substratum, and covered on all sides 

 by the hymenium. 



5. Thelephoracese, plants either erect or diffused over 



the surface of the substratum, one side only (in 

 the case of erect plants usually the under side) 

 covered with the hymenium. 



6. Tremellineae, plants of a gelatinous texture, vari- 



ous in form. 



AGARICAOEJE. The common Mushroom, Agaricus 

 campestris, belongs to this family. The family Agari- 

 caceae is made up of what are now popularly termed 

 agarics. Very many of the species were once placed 

 in the genus Agaricus. The genus became so large that 

 it was subdivided into a large number of subgenera, 

 many of which have recently been raised to the rank of 

 genera. In thus subdividing the old genus Agaricus 

 into a number of genera there has been a lack of uni- 



MUSHEOOM 



1043 



formity on the part of systematists in the choice of a 

 generic name for the common Mushroom. Saccardo 

 retained the genus Agaricus for the common Mushroom 

 and its near allies, although discarding the subgenus 

 Psalliota. Some have employed the genus Agaricus, 

 some Psalliota, others Pratella, and still others propose 

 to restore the antiquated genus Fungus, and call our 

 plant Fungus campestris. This is not the place for a 



1442. Section of a gill of Agaricus campestris, enlarged. 



Tr., trama ; sh., hymenium ; 6., basidium ; St., sterigma ; 

 sp. t spore. 



discussion of the merits of any of these names, but it 

 seems better in the present instance, at least, to use the 

 generic name Agaricus with the limits of Psalliota 

 Fries. 



Other Species of the Genus Agaricus. There are a 

 number of other species of the genus, as thus limited, 

 which, because of their size and esculent qualities, are 

 worthy of mention. 



Agaricus arvensis, the Horse Mushroom, grows in 

 grassy fields and pastures during the autumn. It is a 

 larger plant than the common Mushroom, has a thicker 

 cap, longer stem, and the veil is double, the lower or 

 outer portion splitting radially into a star-shaped fashion 

 and remaining attached to the inner portion. Agaricus 

 silvicolus, the wood-inhabiting Mushroom, grows in 

 woods. The whole plant is whitish, but tinged more or less 

 with yellow, the cap is smooth, and the long stem has an 

 abrupt and broad bulb. The veil is thin, membranaceous, 

 but in some specimens shows a tendency to be double, 

 as in Agaricus arvensis. Agaricus Bodmani grows 

 along the streets of cities in the hard ground between 

 the sidewalk and curbing, and similar places. It is en- 

 tirely white, the cap thick and firm, the stem short, and 

 with a short, thick, double annulus. Agaricus fabaceus 

 (A. subrufescens, Peck) has a light reddish brown cap, 

 a long stem somewhat enlarged below, and a ring which 

 has soft scales on the under side formed, much as in A . 

 silvicolus, from the cracking or splitting of the outer 

 layer. The plant has the taste and odor of almonds. It 

 grows in greenhouses. It sometimes grows in compost 

 heaps. It often forms large clusters of many individuals. 

 It has been successfully cultivated. Agariciis silvati- 

 cus grows in woods during late spring and summer. It 

 is a large plant, usually about the size of the Horse 

 Mushroom, but thinner, and with numerous minute 

 dark scales on the surface of the cap, which form a solid 

 patch of dark color at the center. In age, the cap is more 

 or less flat, and it has been called the flat-cap Mush- 

 room ( A . p lacomyces ) . The stem is long, enlarged belo w, 

 and the ring is double, exactly as in the Horse Mush- 

 room. Agaricus comtulus, a small species, rather rare, 

 but with a wide distribution, is regarded with suspicion 

 by some. 



COPRINUS. In the genus Coprinus, 3 of the edible 

 species are quite common. The spores are black and 

 the gills and more or less of the cap dissolve at maturity 

 into a black fluid. 



