With respect to plants, this subject has been discussed by Nageli in an admirable essay.

He admits that natural selection has effected much, but he insists that the families of plants differ chiefly from each other in morphological characters, which appear to be quite unimportant for the welfare of the species.

He consequently believes in an innate tendency towards progressive and more perfect development.

He specifies the arrangement of the cells in the tissues, and of the leaves on the axis, as cases in which natural selection could not have acted.

To these may be added the numerical divisions in the parts of the flower, the position of the ovules, the shape of the seed, when not of any use for dissemination, etc.
There is much force in the above objection.