394 



ORCHIS PYRAMIDALIS. 



PART II. 



with three equal entire lobes, and is produced into an 

 awl-shaped spur, or nectary. It has a small ridge on 

 each side of its narrow base to guide the proboscides 

 of insects to the mouth of the nectary, which, besides 

 being small, is partially closed by the pouch-shaped 

 rostellum, which is placed very low in this species, 

 and is flanked on each side by a distinct stigmatic 



rounded surface (fig. 

 77 s s). The rostel- 

 lum (r) is hollowed 

 out on its under-side 

 in the middle, and is 

 filled with a fluid. In- 

 stead of two little vis- 

 cid discs or balls, as 

 in the Orchis mascula, 

 there is but one which 

 is saddle-shaped (figs. 

 78, 79), carrying on its 

 nearly flat top or seat, 

 the two stalks of the 

 pollinia, of which the 

 two truncated ends 

 firmly adhere to its 

 upper-surface. Before 

 the membrane of the 

 rostellum ruptures, the saddle-shaped disc forms part of 

 its continuous surface. The upper membrane of the 

 disc is rather thick ; it is lined with a layer of highly 

 adhesive matter formed within the rostellum. 



When the flower opens, the saddle-shaped disc is set 

 free by the rupture of the membrane of the rostellum. 

 Then the rostellum, which projects into the minute 

 round orifice of the nectary, is easily depressed by the 

 proboscis of a moth, and as the now naked and sticky 

 under-surface of the saddle-shaped disc is uncovered, it 



Fig. 78. Orchis pyramidalis: Side view of flower, 

 with a portion cut away ; a, anther ; 

 I, labellum ; n, nectary. 



