TLDR
Sterility and fertility of plants when insects are excluded.
The means by which flowers are cross-fertilised.
Structures favourable to self-fertilisation.
Relation between the structure and conspicuousness of flowers, the
visits of insects, and the advantages of cross-fertilisation.
The means by which flowers are fertilised with pollen from a distinct
plant.
Greater fertilising power of such pollen.
Anemophilous species.
Conversion of anemophilous species into entomophilous.
Origin of nectar.
Anemophilous plants generally have their sexes separated.
Conversion of diclinous into hermaphrodite flowers.
Trees often have their sexes separated.via the TL;DR App
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Written by charlesdarwin | On the Origin of Species By Means of Natural Selection
