412 



ANGIOSPERMAEMONOCOTYLEDONES 



entering the flower they do not touch the rostellum. They only come into contact 

 with this when creeping back, as the lower part of the labellum has sprung upwards 

 again in the meantime. The insects then remove the pollinia on their heads or 

 backs, and on visiting another flower deposit them on the stigma and so effect 

 crossing. 



Visitors. W. E. Darwin (Isle of Wight), beside the honey-bee, which is the 

 regular pollinator, observed flies (Sarcophaga carnaria Z., and Coelopa frigida Fall.) 

 and a fossorial wasp (Crabro brevis v. d. Z.). 



2637. E. latifolia All. (Darwin, op.cit., p. 100; Kirchner, 'Flora v. Stuttgart,'' 

 p. 177; MacLeod, loc. cit. ; Kerner, < Nat. Hist. PL' Eng. Ed. i, II, pp. 253-5 ;| 

 Webster, ' Fertlsn. of Epipactis latifolia ' ; Knuth, * Bloemenbiol. Bijdragen.') Thisj 

 species bears wasp flowers. It occurs in two forms : {a) viridans Crantz, withj 

 a broad, ovo-cordate, reddish- violet labellum, the raised parts of which are smooth, 

 or slightly furrowed, or altogether absent ; (3) varians Crantz ( = E. viridiflor 

 Retchb.), with an ovate labellum, reddish in colour with white spots, of which the 



raised parts are indistinct 

 usually smooth, and some 

 times absent. Both for 

 possess the same flowe 

 mechanism, correspondii 

 exactly to that of the tyj 

 species. The terminal lot 

 of the labellum, however, 

 smaller, and possesses 

 joint, but is fastened fir 

 to the basal region. In co^ 

 respondence with this the 

 rostellum projects still further beyond the stigma. Automatic self-pollination is 

 therefore excluded, but Webster says that insect visitors effect self-pollination more 

 frequently than crossing. 



Visitors. These are almost entirely wasps : Darwin records Vespa sylvestris 

 Scop. ; Kerner, V. austriaca Pz.] and Knuth, V. vulgaris Z. ; Loew (Brandenburg, 

 ' Beitrage,' p. 42) V. rufa Z., 5, skg. Webster observed humble-bees as well as 

 wasps. Gerstacker (central mountains of Germany) and Schletterer (Tyrol) saw 

 Bombus hortorum Z. 



Hermann MuUer asserts ('Fertlsn.,' p. 532) that E. viridiflora Retchb. (=E. lati- 

 folia AIL, var. (a) varians Crantz {cf. Max Schultze, 'D. Orchid. Deutschlands, 

 Deutsch-Oesterreichs u. d. Schweiz,' Gera, 1894) has entirely lost the advantages 

 of a viscid rostellum ; only minute pollen-clumps can occasionally be carried away 

 by small insects on this account, and autogamy consequently takes place to a still 

 larger degree than in the next species (E. microphylla). 



2638. E. microphylla Sw. (Darwin, op. cit., p. 102 ; Herm. INIuller, 

 ' Fertlsn.,' p. 532.) Self-pollination takes place regularly in this species, though 

 crossing may also be effected by insects, a part of the pollen adhering to the visitor 

 by means of the mucilage contained in the rostellum. 



Fig. 381. Epipactis laiifolta. All. (after Darwin). Flower from 

 the side, after removal of the perianth leaves, except the labellum 

 (enlarged), a, anther ; /, labellum ; r, rostellum ; j, stigma. 



