PALYNOLOGY OF TWENTY ONE SPECIES OF ECHEVERIA GENUS (CRASSULACEAE) FROM MEXICO – HIGH RESOLUTION STUDY

Abstract

Mexico has the largest diversity of genus Echeveria. To preserve the biological diversity of this highly endemic plant group, as well as to make its industrial production sustainable, the complete knowledge of their attributes is needed. Nevertheless, few taxonomic characteristics for the genus have been registered so far (little of its taxonomy is known, especially about its palynology); some species have not been described yet, and consequently they are not associated to any taxonomic name. The main aim of this paper is to provide data about its palynology. This work characterizes by Scanning Electron Microscope (SEM) the acetolysed pollen of species of the genus Echeveria (Crassulaceae). Twenty species of Echeveria were studied. The samples were subjected to acetolysis, and processed according to conventional method to be analyzed by SEM. The results revealed the following characteristics for Echeveria pollen: it presented isopolar symmetry; solitary free grain; regularly spheroidal shape, mostly with three compound apertures but sometimes with four; size range from small to medium; morphological features that indicate process of harmomegathy. Exine presented ornamentation typically regulate, and sub-layer structure not continuous (semitectate).