Erigeron beyrichii (Asteraceae), a new combination and redefinition of a widespread taxon in the southeastern United States

Abstract

The Erigeron annuus-E. strigosus species complex is an assemblage of several generally narrowly distributed sexual diploid populations in the southeastern United States plus the widespread apomictic polyploid taxa E. annuus and E. strigosus. Erigeron strigosus var. beyrichii has previously been used to describe plants with diffuse branching and smaller capitula, and it has also been presumed to be polyploid and apomictic. An herbarium specimen at the University of Georgia (GA) was examined that is a duplicate of an original Beyrich collection made in ‘Carolina’ in 1833 that was acquired and distributed by the British Museum (BM). Cotton blue in lactophenol stained pollen provides unambiguous evidence for the diploid and sexual condition of the specimen. Digital images of the putative type specimen of the taxon at LE as well as additional digital specimens from BM and HUH were also examined. The evidence supports the new combination Erigeron beyrichii. This is a sexual diploid species on the coastal plain of the United States in South Carolina, Georgia, Florida, and Alabama. The nomenclatural update brings the taxon into parallel status with other sexual diploid taxa that have recently been described in the complex.