THE PSEUDORHIZA OF COPRINUS MACRORHIZUS 359 



Hitherto, the pseudorhiza or rooting base of the stipe of Coprinus 

 macrorhizus has nowhere been adequately described. In 1911, 

 Weir gave an erroneous account of the way in which it arises. He 

 referred to pseudorhizae definitely as roots {Wiirzeln). Translated 

 from the German, one of his statements is as follows : " The direction 

 of growth of the root in a homogeneous substratum is vertically 

 dowTiwards. Hard bodies are avoided by lateral twisting." ^ 

 Again, in describing the origin of the " roots," he says that at first 

 a knot of hyphae comes into existence something like that of the 

 sclerotium of Coprinus stercorarius. " The knot . . . increases in 

 size, begins to elongate, and behaves itself in its upper and lower 

 halves in a different manner, in that the hyphae of the under half 

 become positively geotropic. Soon after the formation of this 

 rudiment {Anlage), the hyphae on the under side become matted 

 at one point and grow downwards like a root. It is remarkable 

 that the hyphae, even in the substratum, go on growing so as to 

 form a firm unified structure by means of which they remove them- 

 selves more and more from the light and apparently seek the 

 optimum conditions of moisture and food-materials." 2 His further 

 remarks on this matter it is unnecessary to repeat as, like those 

 just quoted, they are based on the erroneous supposition that the 

 root-like organ of the fungus grows downwards through the sub- 

 stratum like the root of a Phanerogam. I shall now endeavour 

 to show : that the root-like organ is really a pseudorhiza, like that 

 of Collybia radicata ; that, unlike a root, it comes into existence 

 not by apical growth, as Weir supposed, but by intercalary growth ; 

 that it is negatively geotropic and not positively geotropic ; and 

 that, in consequence, it grows upwards and not downwards through 

 the substratum. It is the thin lower end of the pseudorhiza which 

 is first formed and not the thick upper end. 



For the purpose of my investigation, I examined a large number 

 of fruit-bodies of Coprinus macrorhizus which were coming up on 

 a long flat-topped pile of horse manure which had been removed 

 from some stables and was well mixed with straw. The manure 



1 J. Pv. Wrir, •■ Untersuchungen iiberdicGattung Coprinus," Flora, Bd. CIII. 1911, 

 p. 313. 



- Ibid., pp. 312 313. 



