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Symphyotrichum frondosum

(Nutt.) Nesom

Alkali Aster

G4Apparently Secure Found in 9 roadless areas NatureServe Explorer →
G4Apparently SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.139828
Element CodePDASTD8020
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderAsterales
FamilyAsteraceae
GenusSymphyotrichum
Synonyms
Aster frondosus(Nutt.) GrayBrachyactis frondosa(Nutt.) A.G. JonesTripolium frondosumNutt.
Other Common Names
Leafy American-aster (EN) short-rayed alkali aster (EN) Short-rayed Alkali Aster (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-02-04
Change Date1987-09-29
Edition Date2025-02-04
Edition AuthorsSoteropoulos (2025)
Threat ImpactUnknown
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Symphyotrichum frondosum is a wide-ranging annual, occasionally perennial, herb in moist, usually saline soils, of seasonal wetlands in western North America from British Columbia, Canada and Idaho and Wyoming in the United States south to New Mexico to California and Baja California, Mexico. There are over 175 occurrences threatened by development, livestock, lake shore management and recreational activities, hydrological alteration, and invasive species. Little is known about trends, but with a large range extent and large number of occurrences, and no obvious intrinsic vulnerabilities, this species is considered apparently secure.
Range Extent Comments
Symphyotrichum frondosum occurs in western North America from British Columbia, Canada and Idaho and Wyoming in the United States south to New Mexico to California and Baja California, Mexico (FNA 2006). It was introduced in Maine through wool waste (Native Plant Trust 2025). Native range extent was estimated to be approximately 1.7 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are over 175 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, SEINet 2025).
Threat Impact Comments
Although threats are not widely documented, this species is threatened by development, livestock, lake shore management and recreational activities (especially off-road vehicles), hydrological alteration, invasive species (including White Sweet Clover (Melilotus alba), Purple Loostrife (Lythrum salicaria), Houndstongue (Cynoglossum officinale), Giant Burdock (Arctium lappa), Canada Thistle (Cirsium arvense), Diffuse Knapweed (Centaurea diffusa), and Sulphur Cinquefoil (Potentilla recta)), and other threats in some places (Environment Canada 2013, NatureServe 2025), though there is insufficient data, including anecdotal accounts, to understand scope and severity of threats for this species.
Ecology & Habitat

Description

Alkali Aster is an annual with solitary, branched stems which are 5-60 cm high and arise from a taproot. The alternate, linear leaves have entire margins and are up to 6 cm long. Lower leaves have petioles, but become sessile higher up. Foliage is glabrous. Flower heads are borne in open, branched inflorescences arising from the leaf axils. Each flower head has 2-3 series of green, overlapping, lance-shaped involucral bracts which are 5-9 mm long. There are yellow disk flowers and numerous pinkish, filiform rays, which are 2-4 mm long. Each achene has a pappus consisting of numerous soft bristles on top that are longer than the disk flowers.

Diagnostic Characteristics

This species is very similar to the more common A. BRACHYACTIS, but the latter has rays that are less than 2 mm long or are lacking. A. FRONDOSUS might also be confused with ERIGERON ACRIS or E. LONCHOPHYLLUS, but the latter 2 have only 1 main series of involucral bracts. A hand lens and technical key will probably be required for positive identification.

Habitat

Symphyotrichum frondosum grows in "moist, usually saline soils, summer-receding shores of lakes or ponds, vernally moist, alkaline bottoms, marshes, often in steppes" (FNA 2006).
Palustrine Habitats
TEMPORARY POOLHERBACEOUS WETLAND
Other Nations (2)
United StatesN4
ProvinceRankNative
WashingtonSNRYes
ArizonaSNRYes
New MexicoSNRYes
NevadaS3Yes
ColoradoS3Yes
OregonSNRYes
WyomingS3Yes
IdahoSNRYes
MaineSNANo
CaliforniaSNRYes
UtahSNRYes
CanadaN2
ProvinceRankNative
British ColumbiaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
Unknown/undetermined———

—

Plant Characteristics
DurationANNUAL, PERENNIAL, Short-lived
Economic Value (Genus)No
Roadless Areas (9)
California (5)
AreaForestAcres
Excelsior (CA)Inyo National Forest45,607
Glass MountainInyo National Forest52,867
Mt. JacksonHumboldt-Toiyabe National Forest20,721
PaiuteInyo National Forest58,712
South SierraSequoia National Forest8,008
Nevada (2)
AreaForestAcres
Excelsior Mtns.Humboldt-Toiyabe National Forest69,071
Long ValleyHumboldt-Toiyabe National Forest50,472
Oregon (2)
AreaForestAcres
Flag CreekMalheur National Forest7,716
North Fork MalheurMalheur National Forest18,069
References (9)
  1. Environment Canada. 2013. Recovery Strategy for the Short-rayed Alkali Aster (<em>Symphyotrichum frondosum</em>) in Canada [Proposed]. <em>Species at Risk Act</em> Recovery Strategy Series. Environment Canada, Ottawa. XIX pp. + Appendix.
  2. Flora of North America Editorial Committee (FNA). 2006b. Flora of North America north of Mexico. Vol. 20. Magnoliophyta: Asteridae, part 7: Asteraceae, part 2. Oxford Univ. Press, New York. xxii + 666 pp.
  3. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  4. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  5. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  6. Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.
  7. Native Plant Trust. 2025. Go Botany website. Online. Available: https://gobotany.nativeplanttrust.org (accessed 2025).
  8. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  9. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).