MUSHROOM 



ing of 1 1 

 give eitl,. 



which the 



name may be used In 



Uf-tinK s p) 



r h-ih speaking 

 1 are some 



I I Iherefore, to 

 j1 llie word Mush 

 iciuge of forms for 

 horticultural sense 



color, and 

 liUckish in 



the pi 



t sporea 

 i of the 

 uttmg a 

 King It, 



1440. The gardener's Mushroom. Agaricus campestris (X 1 



it is applied to Agaiicus cumpeslris (Fig. 1440) in cul- 

 tivation, and since that is the plant with which we are 

 first interested here, we may proceed at once to a de- 

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

 follow with briefer descriptions and comparisons of a 

 few of the many species belonging to this large group. 

 Form and Structure of Agaricus campestris.— The 

 form of the common Mushroom is more or less um- 

 brella-shaped, and is well represented in Pig. 1441. 

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

 ring(«); and the cap.with the gills on the under side. The 

 cap, 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 field and in cultivation in which the upper 

 surface is more or less brownish, especially as the plants 

 become old. The surface is usually smooth, though it 

 often presents a silky texture from the numerous mi- 

 nute fungous threads or mycelium, the structural ele- 

 ment of the entire plant. While the surface is smooth 

 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 with brownish caps. The "flesh" or "meat" 

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

 indrical, 1-3 in. long by %-% in. in diameter, whitish 

 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 

 lamellae, 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 margin 

 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 the 

 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 tlie plant, and this economy in the 

 arrangement of the gills provides for a very large fruit- 

 ing area. The color of the gills when the plant is verj- 

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



borne on the surf i 



number of spores I 



cap floui a Mushri i 



gills downward on i | if t- < i wlui 



hours The spores tdU tioiu the gills ami pile up in 



iidges, gning an exact print of the spaces between the 

 gills 



The parts of the plants enumerated above 

 aie easily seen Other important structural 

 characters aie seen with the aid of the mi 

 croscope A thm section across the gills 

 wlun s(_<n with the microscope shows the 



tuin give rise to the bu-,iiha (basidium), tlub 

 shaped bodies, which form a palisade li3ei of 

 cells over the cntiie suiface of the gill This 

 pahside Hv er of the bisidia forms the fruit 



\t till c II 1 t fach basidium are either 2 

 (r t --1 111 I I inted processes, the sterig- 

 m It I ( sin„' st( 1 u'ma) These bear each a sin- 

 gli spore thi hw-tdiospore The usual num 

 be- of sterigraata on the basidium in the 

 A^arictui is 4, but m Agaiicus eampestns 

 the number seems to vary from 2 to 4 In 

 ]ilants grown m a Mushroom house, 2 have 

 been 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 

 been determined. 



Development of Agaricus campestris .—The spores of 

 the Mushroom in the field probably often germinate and 

 produce 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 prob- 

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

 this is accomplished by the growrth 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 coursing 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 my- 

 celium, and are composed of numerous very slender and 

 delicate whitish threads. This is the vegetative portion 

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



young plants in a Mushroom bed be washed away, a 

 large number of these cords will be exposed. This is 

 the part of the plant which grows and spreads through 

 the soil, absorbing solutions of the organic matter in the 

 soil for food. 



Button .S7«f/c. — After an abundance of the mycelium, 

 or spawn, is formed there appear here and there on the 



