THE ORCHIDS OF NEW ENGLAND. 



II 9 



Orchid," Darwin mentions first the " shield-like rostellum," 

 a feature at once recalling the True Orchises. This is almost 

 square, and projects beyond the stigma ; it " is supported on 

 each side by sloping sides rising from the upper edge of the 

 stigma, in nearly the same manner as in Spiranthes. The sur- 

 face of the protuberant part of the rostellum is rough, and 

 when dry, can be seen to be formed cf cells ; it is delicate and 

 when slightly pricked, a little milky viscid fluid exudes; it is 

 lined by a layer of very adhesive matter, which sets hard 

 quickly when exposed to the air. The protuberant surface of 

 the rostellum, when gently rubbed upward (as it would be 

 when an insect withdrew its head) is easily removed, and 

 carries with it a strip of membrane to the hinder part of which 

 the pollen-masses are attached. The sloping sides which sup- 

 port the rostellum remain (as in Spiranthes) projecting up like 

 a fork and soon wither." The pollen-masses become attached 

 to the back of the rostellum, much as in Spiranthes, and also 

 before the flower expands, and the anther-cell " ultimately 

 opens widely, leaving the pollen-masses almost naked but par- 

 tially protected within the membranous cup uniting the fila- 

 ment or supporting thread of the anther to the edges of the 

 stigma. The pollen-grains cohere in packets as in Orchis," and 

 these packets are tied together by strong elastic threads," which 

 at their upper ends run together and form a single flattened 

 brown elastic ribbon, of which the truncated extremity adheres 

 to the back of the rostellum. 



" The surface of the orbicular stigma is remarkably viscid, 

 which is necessary in order that the unusually strong threads 

 connecting the pollen packets should be ruptured. The lip is 

 partially divided into two portions ; the tip is reflexed, and the 

 basal portion is cup-formed and filled with nectar." Gray, 

 speaking of this same species says, " All freshly opened blos- 

 soms have the column so directed — a little bowed forward 

 — that the tip of the disc and of the antlier are presented to 



