[Vol. 2 



406 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



range of the fungus. He found a somewhat similar disease 

 of the potato, but clearly distinguished the fungus as another 

 species, as further indicated in another part of this paper. 

 Chief among those who extended our knowledge of the 

 pathology and distribution of the violet root felt fungus was 

 Rostrup ('86), who observed the fungus in Denmark and 

 described its effects on various hosts. 



EARLY TAXONOMIC AND MORPHOLOGICAL ACCOUNTS 



The fungi belonging to the genus Rhisoctonia received 

 attention taxonomically from the earliest mycologists. Brief 

 references should be made to the works of some of those who 

 have presented synopses of the genus or who have contributed 

 to the solution of the problem regarding the taxonomic posi- 

 tion of these fungi. Bulliard (1791) evidently based his 

 description of species upon the observations and data of l)u 

 Hamel and de Bondaroy; emphasizing therefore the sclero- 

 tium as the fruit body, and believing it homologous with the 

 truffle he gave to this fungus on Crocus sativus the name 

 Tuber parasiticum. He contributed nothing further to the 

 morphology of the species. Persoon (1801) did not accept 

 Bulliard 's disposition of the fungus, but named it Sclerotium 

 Crocorum, and gave a diagnosis which, while based on the 

 observations of the earlier writers, did not confuse the sclero- 

 tium with a true fruit body. 



De Candolle (1815 a ), in his first taxonomic discussion 

 employed Persoon 's name for the fungus, and then, after 

 giving the characteristics and parasitism of the species on 

 alfalfa more careful attention, he established (1815, 1815 b ) 

 the genus Rhizoctonia to include two species, R. Crocorum 

 DC. on crocus and other hosts and R. Medicaginis DC. on 

 alfalfa. It will be noted that he adopts Persoon 's specific 

 name for the crocus fungus. De Candolle also considers a 

 doubtful species, R. Mali, reported on apple. 



Nees (1816) placed the crocus fungus in Thanatophytum 

 under the name T. Crocorum. Fries (1823) assigns Rhizoc- 

 tonia to the Sclerotiaceae just following his extensive genus 

 Sclerotium. It is important to note, since Fries' work has been 



