XVI International Botanical Congess
The pollen morphology of 31 neotropical species of the tribe Psychotrieae is studied with LM and SEM. Aphanocarpus, Coryphothamnus, Pagamea, and Pagameopsis have 3-colporate pollen grains with a microreticulate to tectate-perforate sexine. Declieuxia pollen is also 3-colporate but is characterized by a typical Adouble reticulum@. The pollen of Palicourea is inaperturate with an often strongly reduced reticulate, regulate to hamulate sexine. In Psychotria pollen is inaperturate or 2-3-colporate, colpate or porate, with a microreticulate, reticulate or hamulate sexine. Rudgea is often characterized by conspicuous pollen dimorphism. Pollen of brevistylous floewers is usually inaperturate with a spinose tectum. In longistylous flowers, pollen is 3-colporate with a microreticulate to tectate-perforate sexine. It is obvious that the pollen of Psychotreae is rather heterogeneous, however, in combination with other characters, it can be very useful in determining relationships between the genera.