Page:On the Various Contrivances by Which British and Foreign Orchids are Fertilised by Insects, and on the Good Effects of Intercrossing.djvu/37

 seems a most insignificant observation; but see the result. In the early morning, when the bee starts on her rounds, let us suppose that she alighted on the summit of the spike; she would surely extract the pollinia from the uppermost and last opened flowers; but when visiting the next succeeding flower, of which the labellum in all probability would not as yet have moved from the column (for this is slowly and very gradually effected), the pollen-masses would often be brushed off her proboscis and be wasted, But nature suffers no such waste. The bee goes first to the lowest flower, and, crawling spirally up the spike, effects nothing on the first spike which she visits till she reaches the upper flowers, then she withdraws the pollinia: she soon flies to another plant, and, alighting on the lowest and oldest flower, into which there will be a wide passage from the greater reflexion of the labellum, the pollinia will strike the protuberant stigma: if the stigma of the lowest flower has already been fully fertilised, little or no pollen will be left on its dried surface; but on the next succeeding flower, of which the stigma is viscid, large sheets of pollen will be left. Then as soon as the bee arrives near the summit of the spike she will again withdraw fresh pollinia, will fly to the lower flowers on another plant, and fertilise them; and thus, as she goes her rounds and adds to her store of honey, she will continually fertilise fresh flowers and perpetuate the race of our autumnal Spiranthes, which will yield honey to future generations of bees. CHAPTER IV.

Malaxis paludosa; simple means of fertilisation—Listera ovata; sensitiveness of the rostellum; explosion of viscid matter; action of insects; perfect adaptation of the several oegans—Listera cordata—Neottia nidusavis; its fertilisation effected in the same manner as in Listera.

WE now come to the last of the British Orchids, those in which no portion of the exterior membranous surface of the rostellum is permanently attached to the pollinia. This subdivision includes only three genera known to me, namely, Malaxis, Listera and Neottia, which are here grouped together merely for convenience. Malaxis in its fertilisation is an uninteresting form; Listera and Neottia, on the other hand, are amongst the most remarkable of all Orchids from the manner in which their pollinia are removed by insects, through the sudden explosion of viscid matter contained within their rostellums.

Malaxis paludosa. This rare Orchid, the least of the British species, differs from the others in the position of its flowers. In Malaxis the labellum is turned upwards, instead of downwards, so as to afford, as in other Orchids, a landing-place for insects; its lower margin clasps the column, making the entrance into the flower tubular.

From its position it partially protects the organs of fructification. [Fig. XVII.] In most Orchids the upper sepal and the two upper petals afford protection; but here they are reflexed in a singular manner (as may be seen in the drawing, Fig. A), apparently to allow insects freely to visit the flower. This position of the flower is the more remarkable, because it has been purposely acquired, as shown by the ovarium being spirally twisted.

In all Orchids the labellum is properly directed upwards, but assumes its usual position as the lower lip by the twisting of the ovarium; but in Malaxis the twisting has been carried to that degree that the flower occupies the position which it should have held if the ovarium had not been at all twisted, and which the ovarium ultimately assumes when ripe, by a process of gradual untwisting.