Secondary pollen presentation is presentation of pollen to vectors by structures other than anthers, either passively or via a specialized protection and delivery system. The main part of Secondary Pollen Presentation describes secondary pollen presentation genus-by-genus in 25 families. The subject has never been extensively reviewed, although secondary pollen presentation occurs in the largest family of flowering plants, the Asteraceae (Compositae), and a large family of great economic importance, the Leguminosae.
Now material from the scattered literature is brought together and supplemented with original observations. Many species are illustrated and each family is individually discussed. The last two chapters provide an overview of the whole topic. All the main functions that secondary pollen presentation may perform can be carried out in other plants without it. It is concluded from this that the evolution of secondary pollen presentation has been subject to constraint and canalization.
The floral biology of most plants with secondary pollen presentation has not been adequately studied. Appendix 1 points to a wide range of topics on which research at various technical and academic levels is needed. Secondary Pollen Presentation should also become a reference work for morphologists, systematists, and floral ecologists.