136 NATIVE BRITISH ORCHIDACE^ 



In the copy of E.B. in the Royal Horticultural Society Library is a drawing of a 

 Platanthera with three long slender spurs found with a group of Butterfly Orchids at 

 Inwood, June i6th, 1909, which looks like P. chlorantha. 



Sir J. D. Hooker expressed his pleasure at finding specimens intermediate between 

 P. hifolia and chlorantha, and following his usual practice, pronounced them conspecific 

 on the strength of it. Later he confessed: "Perhaps my intermediates between 

 Uahenaria chlorantha and bifolia (of wliich I retain a lively recollection) were of this 

 hybrid nature". J This is interesting as showing that even very great botanists were 

 not always free from bias when they lumped together species previously regarded 

 as distinct, on the ground that intermediate forms occurred. 



Bentham^ says oi chlorantha: "The anther-cells are broadly diverging at the base. 

 But intermediates passing gradually from the broad to the narrow forms have been 

 frequently seen in great numbers at High Force in Teesdale in 1865 ". 



The anther-cells in chlorantha are not always equally wide apart— the angle of 



divergence varies— but only within narrow limits. Any specimens in which it was 



less than the average would appeal to a botanist anxious to reduce the number of 



species as opportune examples of "intermediate forms", though they might in all 



other respects be pure chlorantha. Intermediates of hybrid origin also occur, but are, 



as far as my experience goes, extremely rare. The two species are organised for 



pollination by different species of moths, as Darwin so clearly showed. The differences 



between them go much deeper than the parallelism or divergence of the anther-cells. 



Fertilisation. The length of the spur, one-quarter to one-third full of free nectar, 



the white flowers so easily seen in the dark, and the strong sweet scent emitted by 



night, all show that this species depends for pollination on the larger moths. To these 



the flowers are evidently attractive, for spikes are found with almost all the polUnia 



removed. In Dorset on May 30th I found several plants with last year's spikes still 



persisting and bearing numerous seed-capsules (one had 17). As the slits are so 



narrow it is remarkable that no seeds were left inside, but the valves open wide when 



it is fine and close in wet weather through the lengthening of the capsules. Owing 



to the distance between the viscid discs it often happens that only one poUinium is 



removed at a time. On one spike Darwin found tliree flowers from which both 



pollinia, and eight from which only one had been removed. He saw a specimen of 



Hadena ^dentina with one eye covered by a disc, and one of Vlmia gamma v. atireim 



with a disc fixed to the edge of the eye. Mr Marshall3 took 20 specimens of Cucullia 



tmhratica on an island in Derwent Water, half a mile by water from any spot where 



P. chlorantha grew, of which no less than seven had pollinia of this species affixed 



to their eyes.^The discs are so adhesive that if a bunch of the flowers be carried in 



I Hooker's Uje and Utters, 11, 54. " ^andh. Brit. Flora, ed. 6, p. 445- 



3 Nature,^. 393 (Sept. 12th, 1872). 



