to do is to qiiotL- the iimiik-s i^iveii in the treatises most widely known at the present 

 (lav. I'^)r Polypctalac, Watson's Index has generally been rollowed. 



There arc several ilillicullies whieh arise in attempting to give the liosts accurately. 

 The collector is not alwavs well informed about the Phaenogams of the region in 

 which he collects and it often happens that the infested plant has neither flowers nor 

 fruit, in which case an exact determination is often impossible. Perplexing errors 

 have not infie(juenll\ arisen as, for instance, in the case of the fungus named by 

 Schwcinitz Cacoma Chclidonii^ which, as an examination of the original specimens 

 shows, occurred not on Chelidofii?/?// but on Osniorrhiza^ while another species 

 mentioned bv the same author on Smilax really grew on Rosa. One is surprised at 

 the number of similar errors on the part even of good botanists, and one will fail to 

 lind in this part of the index a number of familiar names of fungi, for the reason that 

 we have discovered errors in the determination of the hosts, which make it necessary to 

 remove them from Polypetalae to other divisions which follow. Furthermore, when 

 we consider how little is known about the Phaenogams of a large part of our country, 

 it is not to be expected that errors'could well be avoided by collectors and travellers. 

 Again, the practice of giving common and popular instead of scientific names causes 

 great confusion. The same common name is applied to widely diflerent plants in 

 ditlerent parts of the country, and it is not unfrequcntly impossible to say what 

 species really is meant. Tiie matter is made still worse by the fact that a good m.any 

 of our fungi have been described or have been included in works by foreign bota- 

 nists and in foreign languages, and ludicrous errors have crept in. Sage-biush, for 

 instance, is not unfrequently translated Salvia instead oi Artetnisia, and this erior, 

 transparent as it is to botanists in this country, may at length become fixed in mycologi- 

 cal literature until, at last, we shall find ourselves searching in Labiatac for what 

 really belongs in Compositac. It is not asking tof) much to insist upon the necessity 

 of giving the scientific rather than the common name and, even \\ hen the collector is 

 not sure of the specific name, it would often be of great help to know the generic 

 name. It would have simplified matters for us in several cases had the collector, 

 instead of saying "poplar," said Populus o\ Liriodendron., as the case might be. 

 So far as possible, wc have here referred populai- to scientific names, but it is proba- 

 ble that we have erred in some cases. 



With regard to the nomenclature of cultivated plants authorities difi'er widely, but 

 although the names we have adopted may not meet the approval of many phaeno- 

 g.imic botanists, mycologists will probably have little difficulty in recognizing the 

 plants intended. In some doubtful cases we have given the common names. 



The nomenclature of the species of fungi is that generally accepted by European 

 mycologists, the name of the original describer being given in parenthesis, followed 

 by the name of the author by whom the species was first placed in the accepted 

 genus. This method, although widely adopted by writers on fungi, does not seem 

 to us to be so satisfactory as that of those phaenogamic botanists who do not use the 

 parenthesis, but this is not the place to institute a change in the prevailing practice. 

 Where the number of species on a given host is small, they are arranged alphabeti- 

 cally, regardless of their systematic position, and the eye will quickly catch the 

 species of a particular order if one has any knowledge of the genera of fungi. If he 

 lias not this knowledge, a host-index wotdd lie of little use no matter on what plan it 



