1042 



j\IU?nR(.)().'\L 



MrsiIKOOM 



Frencli word "mousscron," and is MOmetimcs pronounced 

 "musliraons." or "luuslieroons " by English-speaking^ 

 people in America. Mushroom and toadstool are some- 

 times u.sed as synonymous terms, especially in speak- 

 ing of the- group as a whole. It is difficult, therefore, to 

 give either a satisfactory definition of the word Mush- 

 roojii, or satisfactorily to limit tlie range of forms for 

 which the name may be used. In a horticultural sense 



ridges 



1440. The gardener s Mushroom, Agaricus campestris ( 



it is applied to Arjanms ram pes/ ris (Fig. 1440) in ciil- 

 tivatiun, and since that is the phmt with which we nvr 

 first interested here, we muy prtn-eed at once tu a *U-- 

 seription of its form, structure, development, etc., and 

 follow with briefer descriptions and comparisons of a 

 few of the many species belonging to this large grou]). 

 Form and Sfrurfuv of Agnricns ean)pe.<ifris.—The 

 form of the common Jlushroom is more or less um- 

 brella-shaped, and is well represented in Fig. 144]. 

 The prominent parts of the plant are the stem, with its 

 ring{(r); and the cap, with the gills on the under side. The 

 c:ip, or pileus, as it is technically called, is the upper 

 expanded part, and varies from 2 to 4 or 5 inches in 

 diameter. It is usually white in color, but forms occur 

 both in the ficdd and in cultivation in which the upper 

 sui-face is more or less brownish, especially as the plants 

 become old. 'J'lie surface is usually smooth, though it 

 often presents a silky texture from the numerous mi- 

 nute fungous threads or myceiiuni, the structural ele- 

 ment of the entire plant. While the surface is smootli 

 in a majority of specimens, many forms are more or 

 less scaly, due to the fracture of the surface and sepa- 

 ration of the numerous small areas, especially in the 

 specimens witl) brownish caps. The "flesh " or "meat " 

 of the cap is white. Tlie stem, or stipe, is usually cvl- 

 indrical, 1-3 in. long by ^2-M in. in diameter, whiti'sh 

 in color, and nearly or quite solid. The "ring," or annu- 

 lus, forms a collar joined around the stem near the top. 

 It is very delicate, easily rubbed off, and sometimes 

 not present because the veil from which it is formed is 

 torn in fragments as the cap opens out. The gills, or 

 lainellre, on the under side of the cap are of great im- 

 portance in showing relationship, and also probably in 

 reproduction in the case of plants propagated under 

 natural conditions^ since they form the fruiting surface 

 of the Mushroom. The gills are in the form of narrow, 

 thin plates, shaped somewhat like a knife-blade, at- 

 tached by one edge to the under side of the cap and 

 radiating from a point near the stem out to the mart;in 

 of the cap. The longest gills extend for this distance 

 and mark off triangular areas which are filled with suc- 

 cessively shorter gills, all reaching the margin of tlie 

 cap, so that the entire under surface of the cap is well 

 covered with them. The surface of the gills is the 

 fruiting surface of the plant, and this economy in thi^ 

 arrangement of the gills provides for a very large fruit- 

 ing area. The color of the gills when the plant is wry 

 young is white. They soon, however, become pink iii 



color, and as the plant a^^es become purple-brown or 

 blackish in color, due to the immense number of sjiorcs 

 l)orne on the surface. One can gain a good idea of tlie 

 number of spores borne on a single plant by cutting a 

 cap from a Mushroom, just at maturity, and placing it, 

 .i::ills downward, on a piece of white paper for a f(\\ 

 iiours. The spores fall from the gills and pile up in 

 giving an exact print of the spaces between llie 

 gills. 



The parts of the plants enumerated above 

 are easily seen. Other important structural 

 characters are seen with the aid of the mi- 

 croscope. A thin section across the gills 

 when seen with the microscope shows the 

 structure as seen in Fig. 1442. The middle 

 part of the gill is the trania. On either side 

 of the trama is the suhhymeniur/i, composed 

 of branches from the trama and formiii;; 

 short cells. The cells of the subhymenium in 

 turn give rise to the hasidia (basidium), club- 

 slniped bodies, which form a palisade layer (-f 

 cells over the entire surface of the gill. This 

 palisade layer of the basidia forms the fruit- 

 ing surface, or hipneninm. 



At the end of each basidium are either 2 

 or 4 slender, pointed processes, the sierlij- 

 ■matit f sing, sterigma). These bear each a sin- 

 gle spore, the hnsidiospore. The usual nnnr- 

 ber of sterigmata on the basidium in the 

 Agaricini is 4; but in Agaricns campestris 

 the number seems to vary from 2 to 4. In 

 plants grown in a Mushi-oom house, 2 have 

 i)een found, while plants from the field show 4. 

 I. Whether the number 2 for cultivated forms 



is constant, or 4 for the field forms, has not 

 l»i-i-n determined. 



I>rr<'/opme>if of Agaricuii cainpestris. — The spores rif 

 liie Mushi'oom in the field probably often germinate and 

 ]>roduce new mycelium or "spawn," though this is not 

 necessary for the continuance of the plant from one year 

 to another, since the spawn can live through the winter 

 in the soil, and the following year then spreads. In 

 ordinary Mushroom culture, however, the spores prol)- 

 ahly play little part in the propagation of the plant, since 

 this is accomplished by the growth and propagation of 

 .spawn. If the soil where plants are growing is carefully 

 dug away there will be seen slender and irregular whit- 

 ish cords co)ursing through it, and some of them attached 

 to the base of the stem. These whitish cords are what 

 the horticulturist calls "spawn." They are cords of mi/- 

 ridium, and are composed of numerous very slender and 

 delicate whitish threads. This is the vegetative portion 

 nf the Mushroom. If the soil at the base of a tuft ef 



iltivated Mushroom, Acraricus campestris. 



Ming jilants in a iMushroom bed be washed away, a 

 rge niimlM-r of these cords will l>e exposed. This i> 

 e part of the plant which grows and spreads through 

 e soil, abs()rbing solutions of the organic matter in tln' 

 ^il forfo<Ml. 



!iuHo}i .v///(/c.— AfliM- an abundance of the mycelium. 

 ■ spawTi, is formed there appear here and there on the 



