No. 484] 



CLOSELY RELATED SPECIES 



235 



Thus the range of the species overHes that of the variety. Geo- 

 graphic isolation is wanting. 



When we compare S. cernua with *S. odorata we find again a 

 very strong Hkeness. S. odorata is usually much larger in all 

 parts than the former. The length of the scape relative to 

 that of the leaves is greater in S. odorata, and its leaves are less 

 strictly radical. Those not expert in the genus Spiranthes would 

 often distinguish the two species with difficulty. They might be 

 regarded as elementary species in de Vries's sense. S. odorata 

 has been found in Virginia, Georgia, Florida, Alabama, Louisiana, 

 and Texas, and its range thus coincides widely with that of S. 



S. romanzojjiana Cham, and S. porrifolia Lindl. are very closely 

 related species, which no other species approaches. The former 

 is by very much the more widely dispersed, since it crosses the 

 continent, while S. porrifolia is confined — according to speci- 

 mens seen — within the states of Washington, Oregon, and 

 CaHfornia. S. romanzoffiana is represented in our records by 

 many specimens from these same states, and there is therefore no 

 general geographic separation in this case. 



S. laciniata Ames and S. vernalis Engelm. and Gray are ex- 

 tremely similar but distinct species. The former is confined to 

 Georgia, Florida, Alabama, Louisiana and Texas. S. vernalis 

 occurs in all these states, but reaches far beyond tliis area. 



S. beckii Lindl. and S. gracilis Beck are an iniiiu-diarely counate 

 pair of near affinity. The former grows in the Atlantic states 

 from Massachusetts to Texas. S. gracilis covers the same range, 

 but is also to be found further north and further inland. There 

 is no geogi-aphic isolation. 



Cijpriprdium puhescens Willd. and C. parvi forum Salisb. have 

 had attention at tliis laboratory for several years, observations 

 having Ixcn made in the field and in the herbarium, and coUec- 



Measurements indicate that tliere are two pronounced tendencies 

 as regards size of flower. In life, the plants generally have an 

 appearance of thstinetness, and most field naturalists whose 

 opinions have been asked, have maintained that the two kinds are 

 specifically different. The manuals treat them so. Yet they 



