ORCHIDACEiE 



dry hardwood on a gently undulating interstream area, the soil 

 well drained, composed of a gray, fine sandy loam over a yel- 

 lowish sandy-clay or clay. The woodland consisted of white oak, 

 beech, tulip and chestnut trees, with a few scattering loblolly 

 pines and an abundance of flowering dogwood. Here the under- 

 growth was sparse and the Isotria specimens were scattered over 

 an area of about ten acres, occurring either singly or in open 

 groups of from two to four plants. A composite soil sample of 

 the habitat was tested and found practically neutral to Brom 

 Thymol Blue, and soil shaken from the roots gave approximately 

 the same reaction. 



When we attempt to assemble data relative to Isotria affiniSf 

 we find ourselves in a well-nigh hopeless situation. In our largest 

 herbaria there are but few sheets of this species; sometimes only 

 a photograph rewards a search for specimens. When material is 

 found, the plants are usually incomplete and inadequate for a 

 thoroughgoing study, and examination of the flowers is precluded 

 by the likelihood of damage being done when dissections are 

 attempted. Now and again new stations are reported that it is 

 hoped will relieve the situation, but investigation usually proves 

 that some overzealous novice has confused Isotria verticillata 

 with /. ajjinis. Those who have actually found /. affinis are 

 among the favored few. 



The following notes on the floral structure of Isotria affinis 



were taken from Virginian specimens supplied by Prof. Grimes. 



(Plate 107.) Lip three-lobed as in /. verticillata, but the nerves 



of the lateral lobes irregularly thickened, resembling somewhat 



the streams of tallow that flow down the sides of a lighted candle. 



The elevated callus that extends from the base to about the 



middle of the disc is widely and shallowly grooved, and at the 



tip terminates in blunt, elongated, wart-like processes that stand 



[19] 



