74 Rhodora [April 



opportunities for the multiplication of species. It is a genus that 

 repays intensive observation in the field and prolonged contempla- 

 tion in the herbarium. 



Taken throughout its range Spiranthes, as now limited, includes 

 not less than twenty -two species. Of this number twelve are natives 

 of the United States and Canada. Of extra-limital species only one 

 has been reported from the mainland of South America. Three 

 species are found in Europe, one of these, Spiranthes Homanzoffiana 

 Cham., being also a native of the northern United States. Several 

 are natives of the vast area included in Asia, Malaya, Australia 

 and New Zealand. As to the validity of some of the Asiatic species, 

 there is a difference of opinion and the final treatment of several of 

 these may result in the recognition of a single polymorphic species 

 with an extraordinarily wide distribution. 



In the range covered by Gray's Manual there are three species 

 that frequently present difficulties when a sure diagnosis is attempted. 

 These are 8. cernua L. C. Rich., S. odorata Ltndl., and -S. vernalis 

 Engel. & Gray. Spiranthes cernua is so variable that attempts are 

 sometimes made to discover in it a polymorphic species susceptible 

 of splitting. It is difficult, without microscopical examination, 

 to distinguish it from the variety ochrolcuca Ames. Sometimes it is 

 identified as S. odorata. It would seem that S. odorata owes its 

 success in escaping synonymy to the fact that it was born under 

 authority and subsequently sustained because efforts to recognize it 

 have persisted. I am convinced that S. odorata is eonspecifie with 

 8. cernua. 1 



Spiranthes cernua seems to exhibit a surprising range of variation 

 and sometimes attempts are made to segregate new species from it. 

 These result, I believe, from a misunderstanding of the life history 

 of the species. In my opinion, the range of variation exhibited re- 

 presents different stages of development. The seeds of this species 

 are ripe and ready for dissemination shortly after the flowering period. 

 If the seeds fall in favorable ground and mycorrhizal fungi, presum- 



1 J. K. Small refers Spiranthes odorata Lindl., Gyrostachys ochrolcuca Kydb. and 

 Gyrostachys constricta Small to Ibidium cernuum (L.) House, Fl. Southeastern U. S., 

 ed. 2 (1913) 320. The use of the generic name Ibidium is contrary to the inter- 

 national rules governing botanical nomenclature and should be dropped. It is in 

 the list of nomina relicienda and is also excluded by Article 37 of the international 

 rules of botanical nomenclature adopted at Vienna in 1!)05. There is no sanction 

 for the use of Ibidium as a generic name other than that found in obstinate adher- 

 ence to provincial practice. 



