Lotus corniculatus

Abstract

MR. W. E. HART (NATURE, June 12) is quite right in correcting me on the subject of the fertilisation of Lotus corniculatus. It is the outer whorl of stamens, those opposite the calyx teeth, which continue to grow after the others, and which have their filaments dilated at the top so as to thrust the pollen out of the long sharp tube of the keel. I should scarcely have thought it necessary to acknowledge his courteous correction, if it were not for the following question and answer: How is it, then, that the pollen of the inner and shorter whorl of stamens, which discharge their pollen at the same time as the outer whorl, gets pushed out by the filaments of the outer whorl, since the anthers of the inner whorl lie below the summits of the filaments of the outer whorl? The answer is curious: In the early bud, before the anther cells begin to open, the inner whorl is obviously shorter than the outer whorl, so that the anthers of the former lie in a regular row entirely below the anthers of the latter, apparently for the convenience of close packing in the narrow closed flower. As the anther cells begin to open, which is just before the flower opens, the stamens of the inner whorl grow and approach very nearly in height to the stamens of the outer whorl; and as they shed their pollen from the summit of the anthers, their pollen comes out above the dilated tops of the filaments of the outer whorl, so that it can be pushed forwards by those filaments along with the pollen of their own anthers. The filaments of the inner whorl then wither and become comparatively short, while those of the outer whorl continue to grow, dilate, and stiffen, so as to do the work for all the pollen of both whorls. In the mature opened flower the difference between the two whorls becomes more marked than ever. If I am right, Mr. Hart's detection of my blunder leads to the notice of a curious instance of economy of space and of mechanism.