Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/55

. I. much more abundant than O. pyramidalis. No one would readily have suspected that one chief reason of this difference probably was, that the exposed situation was unfavourable to Lepidoptera, and therefore to the seeding of O. pyramidalis; whereas, as we shall hereafter see, the Bee Ophrys is independent of insects.

Many spikes of O. latifolia were examined, because, being familiar with the usual state of the closely-allied O. maculata, I was surprised to find in nine nearly withered spikes (as maybe seen in the list) how few pollinia had been removed. In one instance, however, O. maculata had been even worse fertilised; for seven spikes with 315 flowers, produced only forty-nine seed-capsules—that is, on an average only seven capsules on each spike. In this case the plants formed larger beds than I had ever before seen; and I imagine that there were too many flowers for the insects to visit and fertilise all of them. On some other plants of O. maculata growing at no great distance, above thirty capsules had been produced by each spike.

Orchis fusca offers a still more curious case of imperfect fertilisation. I examined ten fine spikes from two localities in South Kent, sent to me by Mr. Oxenden and Mr. Malden: most of the flowers on these spikes were partly withered, with the pollen mouldy even in the uppermost flowers; we may therefore infer that no more pollinia would have been removed. I examined all the flowers only in two spikes, on account of the trouble from their withered condition, and the result may be seen in the list, namely, fifty-four flowers with both pollinia in place, and only eight with one or both removed. In this Orchid, and in O. latifolia, neither of which had been sufficiently visited by insects, there were more flowers with one pollinium than with both removed. I casually examined many