Chromosome Numbers, Patterns of Distribution, and Apomixis in Antennaria (Asteraceae: Inuleae)

Abstract

The current study presents 137 new chromosome determinations for Antennaria from throughout North America. Previously unreported species include A. atriceps, A. marginata, A. rosulata, and A. stenophylla. Although a few taxa remain uncounted, a reasonable summary of the chromosomal diversity for the entire genus can be made. Three groups of taxa are recognized based primarily on ploidy level and reproductive mode. One assemblage of taxa (group 1) is always sexual, primarily diploid, and is unrelated to the polyploid agamic complexes of group 3. Another category (group 2) consists of species that occur as diploids or tetraploids and are the probable diploid progenitors of the polyploids. The sexual diploid taxa are distinct morphologically and generally occur in southern latitudes and unglaciated regions. The polyploids (group 3) are frequently widely distributed in both southern latitudes and northern glaciated ones and are morphologically diverse.