NEOTTIE^—LISTERA loi 



mechanism is worth noting — a co-ordination not only of construction, but also of 

 function and time. The insect is unconsciously led to the exact spot where he cannot 

 avoid springing the concealed mine, whose explosion frightens him away with the 

 pollinia attached to his head, so that he does not go on to the stigma of another 

 flower on the same spike but flies away to another plant. So delicate is the adjustment 

 of the mine that Darwin found one which had been exploded by an extremely minute 

 Hymenopterous insect, smaller than the pollinia themselves, which was struggling 

 to escape, its head firmly cemented to the end of the rostellum and the tips of the 



pollinia. 



The following insects were taken May 31st, 1930, visiting the flowers (from which 

 they removed pollinia) at Annegy, Haute Savoie : Eucera kngicomis L. by Mrs Evans, 

 and Empis tesselata F. by Colonel G. H. Evans. H. Miiller took also the following 

 insects with pollinia on their heads: Ichneumon tmiguttatus (i), Alysla (i), Cryptus 

 (8, belonging to 3 species), Phagedon (2), Tryphon (2), Campopkx (i), Microgaster 

 rufipes F. (3), and saw Bombtis agrorum licking honey on several flowers without 

 removing the pollinia. ' I took the sawfly Dokrus picipes Kl. ? on Cephalanthera 

 ensifolia and placed it in a box containing flowers of Listera ovata. I found later it 

 had withdrawn four pollinia on its proboscis. 



2. Listera cordata R. Br. 



PI. 18 A. Lesser Twayhlade 



Rootstock slender, creeping, with a few wliitish thread-like short-haired roots. 

 Stem erect, slender, rarely more than 20 cm. tall, thickened below the leaves by 

 decurrence of their nerves and edges, with 1-2 brownish scale-like lanceolate close- 

 fitting leafless sheaths at the base, and also the new bud; stem above the leaves 

 angled, fluted, glabrous or slightly downy, pale green often reddish, resembling a 

 long peduncle. Leaves two, about the middle of the stem, appearing opposite, sessile, 

 spreading horizontally, triangular with rounded corners and broadly wedge-shaped 

 base, rounded at the apex, entire, often with incurved or wavy edges, glabrous, green 

 and shining above, paler rather grey-green below, 5 -nerved, the mid-rib ending in 

 a fine point, with numerous netted veins on each side. Flowers few (usually 6-12), 

 very small, inconspicuous, green more or less suffused with red, in a short loose 

 feeble slender raceme. Bracts nearly triangular, ovate acute, shorter than the stalk 

 of the ovary, obscurely i -nerved. Ovary nearly globular, shorter than its twisted 

 stalk, angular, light green, glabrous, with six reddish ridges. Sepals oblong, rounded 

 at the tip, green, rather spreading, persisting on the fruit. Petals very similar and 



' Muller, loc. cit. 



