Pollen morphology of North American species of Antennaria (Asteraceae: Inuleae)

Abstract

The pollen of 90 individuals representing 28 species and subspecies in the genus Antennaria is described through the use of light and scanning electron microscopy. Two morphological groupings separated on the basis of exine morphology are evident from cluster analysis. One group consists of those species and subspecies in which the exine is perforate and the other group consists of those individuals in which the exine is not perforate (perforate-reticulate or striate-perforate-reticulate). These two pollen morphological groups do not correspond with previously defined groupings based on morphology or cytogenetics. Both large (> 19 μm in diameter) and small pollen grains occur in each of the cluster groups. Similarly, both long- (> 2 μm) and short-spined individuals occur in each of the cluster groups. Used in combination, these characters do however exhibit some sectional affinities. Section Alpinae is characterized by pollen grains with long spines. Section Dioicae is characterized by small pollen grains. Section Plantaginifoliae is characterized by large pollen grains with long spines. Species included in sections other than these are not consistent in their pollen morphology. The pollen groups recognized in this preliminary study form a basis for future studies at the geographic or population level.