ORCHIDACEiE 



ferences that are emphasized will prove diagnostic of two distinct 

 species renaains for further consideration. It is true, however, that 

 the aura of these species, widely separated geographically, is dis- 

 tinctive. 



If, at this point, we review the species of the northeastern 

 United States included within the range covered by the seventh 

 edition of Gray's Manual, we find that the Pogonia alliance has 

 five representatives. In the following pages these are arranged 

 for discussion in the order that seems best suited to an illumi- 

 nating survey of their differentiating characters. 



TRIPHORA Nutt 



Triphora trianthophora {Sw.) Rydb. in Britton's Man. 

 (1901) 298. Helleborine mariana Pluk. Mant. (1700) 100, t. 348, 

 f. 6. Arethusa trianthophora Sw. in K. Vet. Akad. Stockh. Nya 

 Handl. 21 (1800) 230. Arethusa parviflora Michoc. Fl. Bor. Am. 

 2 (1803) 160. Triphora pendula Nutt. Gen. 2 (1818) 193. Po- 

 gonia pendula Lindl. in Bot. Reg. (1825) t.908. Pogonia trian- 

 thophora BSP. Prelim. Cat. N. Y. (1888) 52. 



Triphora trianthophora is the only species of Triphora within 

 the territory covered by Gray's Manual. In fact, with the excep- 

 tion of a species recently discovered in Florida that appears to 

 be closely allied with T. gentianoides (Sw.) Ames & Schltr., it 

 is the only representative of Triphora in the United States. Its 

 nearest ally is the Mexican T. mexicana (Wats.) Schltr. It dif- 

 fers from all other New England orchids in its vegetative sys- 

 tem, and has been very casually mentioned in botanical writings 

 with regard to the subterranean phenomena that characterize 

 it. Lownes studied the behavior of tubers in colonies under 

 observation near Camp Algonquin, New Hampshire, and pub- 

 lished a very illuminating note regarding them in Rhodora for 



[9] 



