British Clavariae. A. D. Cotton & E. M. Wakefield. 165 



a monograph at a later date. The present revision does not 

 profess to furnish a complete list of the British species. Indeed 

 it is clearly jireliminary, since many specimens had to be left 

 unidentified, and species apparently new continue to appear 

 every season. We feel confident however that the interpreta- 

 tion here given of the old and doubtful species is in the main 

 correct and that, though new species may be added, little 

 fundamental alteration will be necessary. As it has not been 

 possible to pay detailed attention to the subject since 1914, 

 and as there is no prospect of doing so in the immediate future, 

 it seems advisable to publish without further delay the results 

 so far obtained. 



With regard to the diagnostic characters adopted, we have 

 used micro-characters in conjunction with field characters. 

 The form and size of the spore, except in the ochraceous-spored 

 section where they are singularly uniform, proved surprisingly 

 varied and useful. But although so invaluable we have never 

 used micro-characters in separating one species from another 

 unless the plant was also amply distinct in form, colour, or 

 other field character. The spores in some cases afford a more 

 accurate and precise means of expressing the difference between 

 allied species than form or colour. This is well seen in the 

 yellow unbranched section and especially in the case of the two 

 species C. inaeqiialis and C. persimilis. To the trained eye 

 these are usually distinguishable in the field, but at times the 

 colour is identical. If examined with the microscope, however, 

 the oblong spore of the latter with its marked lateral apiculus 

 immediately separates it from the globose spinose spore of the 

 former, and if the specimens are sorted out by this method 

 the separation is confirmed by the difference in colour which 

 is assumed on drying. 



The variation of the spore both in form and size, and hence 

 the difficulty in gauging its value as a diagnostic character, 

 has been commented on by several writers, both systematists 

 and experimentalists, e.g. Sherbakoff in the case of Fusarium, 

 Brierley in Botrytis, and by Thom to a lesser extent in the 

 case of Penicillium. The present study has not revealed any 

 marked variation in the genus Clavaria, but merely that which 

 any systematist would consider normal for the Hymertomycetes 

 and indeed for the larger fungi generally. The spores of all 

 species of Clavaria vary within certain limits, and those of some 

 species much more so than others; indeed the tendency to great 

 variation may be regarded as characteristic of certain species. 

 In connection with spore-measurements two points must be 

 borne in mind, (i) the necessity of dealing with mature spores 

 -and (2) the possibility of the existence of strains or races which 



