Short-rayed alkali aster (Symphyotrichum frondosum) COSEWIC assessment and status report: chapter 3
Species Information
Name and classification
Scientific name:
Symphyotrichum frondosum (Nutt.) Nesom, Phytologia, 77 (3): 282. 1994
Basionym (Nesom 1994)
Aster frondosus (Nutt.) Torr. & Gray, A.
Flora of North America: 2(1): 165. 1841.
Brachyactis frondosa (Nutt.) A. Gray, Proc. Am. Acad. Arts viii. (1873) 647.
Tripolium frondosum Nutt., Trans. Amer. Philos. Soc. N. S. vii. (1841) 296.
Common name:
- short-rayed aster or alkali aster (Douglas et al. 1998)
- short-rayed alkali aster (ITIS 2004)
Family name:
Asteraceae (aster family)
Major plant group:
Eudicot flowering plant
Kartesz (1999) lists this species as Brachyactis frondosa. Aster frondosus is the name used for this species in BC (Douglas et al. 1998). However, current research has shown that Aster sensu stricto does not apply to North American members of the tribe Astereae (Nesom 1994, Noyes and Rieseberg 1999, Semple et al. 2001). The single exception is Aster alpinus L. (Nesom 1994, ITIS 2004). Aster frondosus has been placed in the genus Symphyotrichum by Nesom (1994). It has clearly been demonstrated that the genus Symphyotrichum is unrelated to Aster sensu stricto (Noyes and Rieseberg 1999). The Integrated Taxonomic Information System (2002) lists Aster frondosus as “not accepted” and Symphyotrichum frondosum as the “accepted” taxonomic status of this species. Treatment of the genus Symphyotrichum for Flora of North America is currently being prepared by Luc Brouillet and others. They will be using the nomenclature outlined above (Brouillet pers. comm. 2003, Semple pers. comm. 2003). In this report, we follow Brouillet et al.
Morphological description
An annual herb 5 to 60 cm tall, much branching (Figure 1), usually decumbent (Wiggins 1980) but can be erect, arising from a tap-root (Douglas et al. 1998). Heads usually very numerous in spicately paniculate inflorescences (Munz and Keck 1970). Ray flowers 1.5-2 mm long, barely exceeding the disk flowers, conspicuous pink to white in living specimens, drying to inconspicuous white once pressed (Douglas et al. 1998, Lomer 1996). Involucral bracts 5-9 mm tall, subequal to moderately graduated, obtuse (St. John 1937). A similar species, Symphyotrichum ciliatum is distinguished from S. frondosum by its lack of ray petals.
Figure 1. Symphyotrichum frondosum (Source: Douglas et al. 1998. Used with permission.)
Genetic description
Chromosome numbers for S. frondosum are reported as n=7 (Houle and Brouillet 1985).
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