Note 38 — Chapter X · THE SHAPES OF FLOWERS.

It has been pointed out to me that “the extreme development of the corolla so often found in the outer flowers or on the outer side of the outer flowers in closely-packed inflorescences, associated as it often is with disappearance of stamens or carpels or both, is usually put down to specialization of these outer flowers for attractive purposes. Since the whole inflorescence is increased in conspicuousness by such a modification, it is supposed that natural selection favoured those plants which sacrificed a portion of their seed-bearing capacity for the supposed greater advantage of securing more insect visits.” But granting this interpretation, it may still be held that increase of attractiveness due to increase of area must be achieved by florets at the periphery, and that their ability to achieve it depends on their having an outer, unoccupied, space which the inner florets have not; so that, though in a more indirect way, their different development is determined by different exposure to conditions.