Taxon Report

Symphyotrichum lentum (Greene) G.L. Nesom

Suisun Marsh aster

Print Report


Taxon Summary

Symphyotrichum lentum, commonly known as Suisun Marsh aster, is a perennial rhizomatous herb in the Asteraceae that is found only in California. It occurs within Marshes and swamps (brackish, and freshwater), growing at elevations from 0 to 3 meters. Symphyotrichum lentum is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.

  Classification
Scientific Name:
 Symphyotrichum lentum (Greene) G.L. Nesom
Common Name:
 Suisun Marsh aster
Family: Asteraceae
Element Code: PDASTE8470
USDA Plants Symbol: SYLE2
Synonyms/Other Names:
  • Aster chilensis Nees var. lentus (Greene) Jeps.
  • Aster lentus Greene

Ecology and Life History
Lifeform: perennial rhizomatous herb
Blooming Period: (Apr)May-Nov (Apr)May-Nov
Elevation: 0-3 (0-10)
General Habitats: Marshes and swamps
Microhabitat:
Microhabitat Details:

Conservation Status
CA Rare Plant Rank: 1B.2
Global Rank: G2
State Rank:
 S2
State List: None
Fed List: None
Other Status: SB_CalBG/RSABG; SB_USDA
CRPR Changes:

Occurrence Data from the CNDDB
Total Occurrences: 185
Element Occurrence Ranks:
   Excellent (A) 7
   Good (B) 32
   Fair (C) 51
   Poor (D) 15
   None (X) 0
   Unknown (U) 80

Location
California Endemic:  True
California Counties and Islands: Name (Code)
Contra Costa (CCA), Napa (NAP), Sacramento (SAC), San Joaquin (SJQ), Solano (SOL), Yolo (YOL)
Quads: Name (Quad Code)
Antioch North (3812117), Benicia (3812212), Bouldin Island (3812115), Cordelia (3812222), Cuttings Wharf (3812223), Denverton (3812128), Dozier (3812137), Elmira (3812138), Fairfield North (3812231), Fairfield South (3812221), Holt (3712184), Honker Bay (3812118), Isleton (3812125), Jersey Island (3812116), Knights Landing (3812176), Liberty Island (3812136), Lodi South (3812113), Napa (3812233), Rio Vista (3812126), Sacramento West (3812155), San Quentin (3712284), Stockton West (3712183), Terminous (3812114), Thornton (3812124), Vine Hill (3812211), Woodward Island (3712185)

Threat List Data from the CNDDB

Threat List Total: 10
EOs with Threat Listed: Total EOs % of EOs
70 38 %
Waterway bank protection/maintenance 34 18%
Erosion/runoff 19 10%
Recreational use (non-ORV) 16 8%
Non-native plant impacts 14 7%
Other 12 6%
Road/trail construction/maint. 5 2%
Biocides 4 2%
Development 2 1%
Foot traffic/trampling 2 1%
Military operations 1 0%

Notes
Intergrades into A. chilensis. See Manual of the Botany of the Region of San Francisco Bay, p. 180 (1894) by E. Greene for original description and Phytologia 77(3): 286 (1994) for revised nomenclature.
Threats:
Seriously threatened by marsh habitat alteration and loss, and erosion. Possibly threatened by herbicide application.
Taxonomy:
USFWS uses the name A. chilensis var. lentus.

Selected References

Citation California Native Plant Society, Rare Plant Program. 2026. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 6 February 2026].