ORCHIDEAE 



411 



2635. C. rubra Rich. (Kirchner, ' Neue Beob.,' p. 12, 'Beitrage,' p. 12, 

 ' Flora V. Stuttgart/) The mechanism of the beautiful purple-red, rarely white 

 flowers of this species agrees essentially with that of C. pallens. The anterior 

 expanded part of the labellum, serving as a platform for insects, is however longer 

 than in that species. The reddish pollinia are situated on the posterior margin of the 

 stigma, and free themselves from the loculi. The stigma is very sticky. Near 

 Ueberlingen, Kirchner observed 

 that the pollinia were removed 

 from many flowers, insect-visits 

 having therefore taken place. 

 Warnstorf describes the pollinia 

 as sessile, but separate to their 

 bases. The pollen-grains are not 

 cemented together, but distinct, 

 and only loosely connected, 

 rounded tetrahedral, pale bluish 

 in colour, tuberculate, on an 

 average 31 /u, in diameter. 



826. Epipactis Rich. 



Nectar half-concealed. 



2636. E. palustris Crantz. 

 (Darwin, op. cit., p. 93 ; Kirchner, 

 'Flora V. Stuttgart,' p. 176; 

 MacLeod, Bot. Jaarb. Dodonaea, 

 Ghent, v, 1893, pp. 324-5.) 

 In the horizontal flowers of this 

 species, the part of the labellum 

 projecting beyond the other 

 perianth leaves serves as a plat- 

 form for insect visitors. It is 

 united by a joint to the lower 

 part, which forms a cup contain- 

 ing nectar, is elastic and movable, 

 and somewhat bent upwards. 

 The lower part of the stigma is 

 bilobed; a small, almost globular 

 rostellum projects somewhat 

 above it, and is covered with a 

 soft, elastic cap, viscid internally. 



Fig. 380. Epipactis i>alustris. Grants {sStex'Da.TKiTi). A. Side 

 view of a flower, after removal of the lower perianth leaves. B. 

 Do., with the front part of the labellum pressed down in the same 

 way as by an insect visitor. C. Flower from the side, after 

 removal of all the perianth leaves except half the labellum (further 

 enlarged). D. Column from the front, after removal of all the 

 perianth leaves : the rostellum is actually situated somewhat higher 

 (further enlarged). a, anther with its two loculi open ; a', vestigial 

 anthers ; /, labellum ; r, rostellum ; j, stigma. 



This can easily be lifted off" by pressure from inside 

 and below. The anther dehisces longitudinally before the flower opens, so that the 

 two sessile pollinia are exposed. Their pollen-grains are united into small packets 

 by elastic threads, and the threads are joined into cords which are fastened to the 

 posterior lobes of the cap covering the rostellum. 



Insects alighting on the front part of the labellum press it downwards, so that on 



