Virguloid Asters

Virguloid asterSymphyotrichum subg. Virgulus (Raf.) Nesom includes mostly x=5 species plus one x= 30 and two x=4 species of North American asters. These have been treated as a genus (Lasallea, Virgulus) or as a subgenus within Aster or Symphyotrichum. Semple and Brouillet (1980) were the first to recognize the group. Species generally share cormoid rhizomes and similar basal rosette leaves and often patent branching as well as a distinctive karyotype, but they differ greatly in the upper leaf and head array traits. Most species occur in the eastern United States, with some native to western North America from Alaska and the northern Yukon to southern Mexico.

Morgan and Holland (2012) using ITS and ETS sequence data demonstrated that there was likely reticulate evolution of involving some species of Symphyotrichinae.  Symphyotrichum gypsophila may be related to Ampelaster.  The Mexican virguloid species are likely related to Psilactis rather than subg. Virgulus, which itself may belong in a clade with Almutaster and Psilactis rather than Symphyotrichum.  Further work is need to clarify generic limits and relationships in the Symphyotrichinae.  The treatment of taxa by Brouillet et al. (2006 FNA) is followed below with some modifications.

Classification and Illustrations

Symphyotrichum Sect. Concolores

Symphyotrichum Sect. Grandiflorae

        Mexican (may not belong in genus)

  • Symphyotrichum hintonium
  • Symphyotrichum moranense
  • Symphyotrichum trilineatum

Symphyotrichum Sect. Patentes

  Symphyotrichum subsect. Patentes

  Symphyotrichum subsect. Brachyphylli

Symphyotrichum Sect. Polyliguli

Symphyotrichum ×amethystinum (S. novae-angliae × S. ericoides)

Symphyotrichum Sect. Ericoides

Morgan, D.R. and B. Holland. 2012. Systematics of Symphyotrichinae (Asteraceae: Astereae): Disagreements Between Two Nuclear Regions Suggest a Complex Evolutionary History. Syst. Bot. 37: 818–832.

Last updated 16 October 2019 by J.C. Semple

© 2019, J.C. Semple, including all photographs unless otherwise indicated