FERTILISATION OF Ol'IUiYS APIFEHA 2S5 



THE FERTILISATION OF OPHKYS APIFE11A. 

 By Colonel M. J. Godpeet, F.L.S. 



Even a cursory glance at the flowers of the Bee Orchis is enough 

 to show that they are primarily designed for cross-pollination by 

 insects. The bright-coloured sepals are well calculated to catch the 

 eye, and the effect is heightened by the dark, strongly-contrasting 

 lip. Self-fertilised flowers have no need of attractive colours, and 

 natural selection could not evolve superfluous ornamentation of no 

 use to the plant. 



The whole construction of the flower in 0. apifera is so clearly 

 planned to secure cross- pollination by insects that it would be unin- 

 telligible on any other assumption. The intensive packing of the 

 immense quantity of pollen-grains into two extremely small and 

 portable pollinia — the attachment of each pollinium by its caudicle 

 or stalk to a ball of very adhesive matter which sets hard like cement 

 on exposure to the air — the immersion of this ball in a pouch full of 

 moisture which preserves its viscidity till required for action — the 

 swinging back on its hinge of the pouch when touched by an insect 

 entering the flower, so that the viscid ball adheres to its head — the 

 downward movement of the caudicles during the insect's flight, from 

 a vertical to a horizontal position on a level with the stigma of the 

 next flower visited — the bend or elbow in the caudicles tilting the 

 pollinia upwards at the requisite angle to touch the inner roof of the 

 chamber on which the stigma is situated— would all be meaningless if 

 the pollinia are not required to be transferred from flower to flower. 

 If O. apifera was originally designed to fertilise itself, they would 

 be actually detrimental to this object, for they tend to remove the 

 pollinia from the flowers which they might otherwise fertilise. 



The mechanism of the flower in all other European species of 

 OpJirys is identical with that of O. apifera, but all these species 

 (1 believe without exception) are entirely dependent on insects for 

 pollination, for without their visits no seed-capsules are produced. 



The mechanism of 0. apifera, constructed on the same principle, 

 can only be reasonably interpreted as intended to operate in a 

 similar way. 



It therefore comes as a shock to find that, whether in England, 

 France, Switzerland. Italy, or Algeria, O. apifera is constantly self- 

 fertilised. The pollinia emerge from the anther-cells, dangling on 

 the long and flexible caudicles like a pair of cherries on their stalks, 

 till they become poised in front of the stigma, and, oscillating with 

 every breath of air, one or perhaps both swing against the stigma, 

 and adhere. They swell in size, emit pollen-tubes, and fertilise the 

 ovules in the same way as when brought by insects. It looks as if 

 the caudicles had become too long and too flexible, but as their 

 length and flexibility just suffice to bring them within touching- 

 distance of the stigma, a kind of short circuit has been set up, 

 perhaps in the first instance by accident. Once this had happened 

 it was likely to become increasingly frequent, for the offspring of 

 self -fertilised plants (in which every flower sets a capsule) is bound 



