Northern Bog Aster

Symphyotrichum boreale (Torr. & Gray) A. & D. Löve

Symphyotrichum boreale
Robert H. Mohlenbrock. USDA SCS. 1989; downloaded from the USDA Plants Database

Dicotyledoneae (Dicots)
Asteraceae (Aster Family)
State Protection
Listed as Threatened by New York State: likely to become Endangered in the foreseeable future. For animals, taking, importation, transportation, or possession is prohibited, except under license or permit. For plants, removal or damage without the consent of the landowner is prohibited.
Federal Protection
Not Listed
State Conservation Status Rank
Imperiled in New York - Very vulnerable to disappearing from New York due to rarity or other factors; typically 6 to 20 populations or locations in New York, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines.
Global Conservation Status Rank
Secure globally - Common in the world; widespread and abundant (but may be rare in some parts of its range).


Did you know?

The difficulty of exploring the wet, unstable, and often shrubby bog habitat of this aster prevents many people from seeing it. Even when the habitat is surveyed this aster's narrow stems and leaves are often overlooked unless it is flowering.

State Ranking Justification

There are 15 known populations and equally as many historical populations. More surveys are needed at these historical locations. This aster has a broad distribution across the state, but a rather narrow habitat requirement (bogs and fens). It is unclear if this is truly a rare plant, or if it is often overlooked.

Short-term Trends

There is a stable population within its range in New York. Five of the original 23 historical records have been rediscovered and nine new occurrences have been found since 1989.

Long-term Trends

There are as many current populations as have been known in the past so there does not seem to be a decline over the long term. Populations should continue to remain steady because much of its habitat is protected or under low threat.

Conservation and Management


Some development is taking place near a couple of sites where it occurs but there appears to be no direct threat to the wetlands.

Conservation Strategies and Management Practices

Provide a large buffer to the wetlands where it occurs to protect the water quality and preserve the hydrology of the wetlands.

Research Needs

There are no research needs to report at this time.



An aster mainly of calcareous fens, particularly rich shrub fens and medium fens, but also found in openings within coniferous swamps, sedge meadows, and possibly shorelines of lakes and ponds (New York Natural Heritage Program 2005). Rare in cold bogs (Rhoads and Block 2000, as Aster borealis). Fens, bogs, open conifer swamps (cedar, tamarack, spruce); wet, often sedgy, sand flats, shores, meadows, and swales (Voss 1996, as Aster borealis). Cold bogs (Gleason and Cronquist 1991, as Aster borealis). Calcareous bogs, swamps, wet gravels and shores (Fernald 1970, as Aster borealis).

Associated Ecological Communities

  • Inland poor fen (guide)
    A wetland fed by acidic water from springs and seeps. Plant remains in these fens do not decompose rapidly and thus the plants in these fens usually grow on older, undecomposed plant parts of mostly sphagnum mosses.
  • Marl pond shore* (guide)
    The marly shore of an inland pond. Marl is a whitish substance that is deposited from water that has a lot of calcium dissolved in it. The whitish substance is calcium carbonate, people used to harvest marl to lime agricultural fields. Water levels of marl pond shores may fluctuate seasonally. There are usually only a few plants.
  • Medium fen (guide)
    A wetland fed by water from springs and seeps. These waters are slightly acidic (pH values generally range from 4.5 to 6.5) and contain some dissolved minerals. Plant remains in these fens do not decompose rapidly and thus the plants in these fens usually grow on older, undecomposed plant parts of woody material, grasses, and mosses.
  • Northern white cedar swamp* (guide)
    A swamp that occurs on organic soils in cool, poorly drained depressions in central and northern New York, and along lakes and streams in the northern half of the state. These swamps are often spring-fed with continually saturated soils. Soils are often rich in calcium. The characteristic tree is northern white cedar, which makes up more than 30% of the canopy cover.
  • Red maple-tamarack peat swamp (guide)
    A swamp that occurs on organic soils (peat or muck) in poorly drained depressions. These swamps are often spring fed or enriched by seepage of mineral-rich groundwater resulting in a stable water table and continually saturated soil. The dominant trees are red maple and tamarack. These species usually form an open canopy (50 to 70% cover) with numerous small openings dominated by shrubs or sedges.
  • Rich graminoid fen (guide)
    A wetland of mostly grasses usually fed by water from highly calcareous springs or seepage. These waters have high concentrations of minerals and high pH values, generally from 6.0 to 7.8. Plant remains do not decompose rapidly and these grasses usually grow on older, undecomposed plant parts.
  • Rich hemlock-hardwood peat swamp* (guide)
    A swamp that occurs in central New York in depressions or concave slopes which receive groundwater discharge. These swamps usually have a fairly open canopy (50 to 70% cover), scattered shrubs, and a diverse groundlayer with sedges, mosses, and forbs. The characteristic canopy trees are eastern hemlock (which usually have at least 20% cover), red maple, yellow birch, black ash, tamarack, white pine, smooth serviceberry, balsam fir, and northern white cedar.
  • Rich shrub fen (guide)
    A wetland with many shrubs that is usually fed by water from springs and seeps. These waters have high concentrations of minerals and high pH values, generally from 6.0 to 7.8. Plant remains in these fens do not decompose rapidly and thus the plants in these fens usually grow on older, undecomposed woody plant parts.
  • Sedge meadow (guide)
    A wet meadow community that has organic soils (muck or fibrous peat). Soils are permanently saturated and seasonally flooded. The dominant herbs must be members of the sedge family, typically of the genus Carex.

* probable association but not confirmed.

Associated Species

  • Acer rubrum var. rubrum (common red maple)
  • Acer x freemanii
  • Andromeda glaucophylla
  • Aster puniceus
  • Calamagrostis canadensis
  • Carex lasiocarpa
  • Chamaedaphne calyculata (leatherleaf)
  • Cladium mariscoides (twig-rush)
  • Drosera intermedia (spatulate-leaved sundew)
  • Eleocharis rostellata (walking spike-rush)
  • Kalmia polifolia (bog laurel)
  • Larix laricina (tamarack)
  • Menyanthes trifoliata var. minor
  • Myrica gale (sweet gale)
  • Rhynchospora alba (white beak sedge)
  • Sarracenia purpurea (purple pitcherplant)
  • Solidago uliginosa (bog goldenrod)
  • Sphagnum centrale
  • Sphagnum contortum
  • Sphagnum squarrosum
  • Trichophorum alpinum (lime-loving club sedge)
  • Vaccinium corymbosum (highbush blueberry)
  • Vaccinium macrocarpon (cranberry)


New York State Distribution

This aster has a specific habitat requirement, but its general distribution is throughout New York State. One may encounter this aster in any bog or fen habitat. It is unclear if its rarity status is due to a limited number of populations, or if it is simply overlooked.

Global Distribution

A northern species that ranges south to New Jersey, West Virginia, Illinois, Iowa, Colorado, Idaho, and Washington.

Identification Comments

General Description

Northern bog aster grows from very slender underground runners less than 1/16" thick. The very slender stems, about 1/8" thick, grow from 6 inches to 3 feet tall and are hairless in the lower half but have lines of hairs in the upper half. The stem leaves are long and narrow with a long pointed tip and a base that is rounded to slightly clasping the stem. The rough margins are inrolled and may have a few scattered teeth but usually have no teeth at all. The main vein on the underside of the leaf is sometimes hairy. The lower leaves have often withered and fallen off by the time the plant flowers. There are up to 20 branches at the top of the plant with one flower head at the end of each branch. Small plants usually only have one flower at the top. The small leaf bracts around the bottom of the flower head are overlapping and held tight to the head. There are 20-30 white to pale rose or bluish ray flowers, 1/2 to 3/4" in length, around a yellow disk which turns purplish-brown with age. The flattened fruits have one rib on each side and are sparsely hairy.

Identifying Characteristics

This aster has slender, solitary stems arising from nearly filiform and stoloniferous elongate rhizomes that are 0.8-2 mm thick. The leaves are very narrow (usually less than 1 cm wide), linear or nearly so, 5-15 cm long, and very gradually taper to a slender tip. The leaf margin is entire (although often rolled along the edge), but the margin may have a harsh scabrous feeling. The lower surface of the leaf has clearly marked reticulation. The involucres are 5-8 mm high. There are usually 1-12 (20) flowering heads with 20-50 ray flowers each, the color ranging from white to pale blue or lavender. The phyllaries are in 3-5 series, the outer much shorter, linear-attenuate, thin and flexible, 0.5-1 mm wide, and with a slender green midrib.

Best Life Stage for Proper Identification

This aster is best identified when in flower, although those very familiar with this plant may be able to identify it vegetatively. To verify the identification, a voucher specimen of the entire plant should be collected. This voucher should include the stem with roots and flowers or fruits.

Similar Species

Symphyotrichum lanceolatum (Aster lanceolatus) has leaves that are sessile, on a short petiole, or slightly clasping the stem. The rhizome is thicker (usually at least 2.5 mm thick, and there are many flower heads (more than 20), with 20-40 ray flowers on each head. These ray flowers are white to lavender or blue. The leaves are also usually broader (5-20+ mm broad). Symphyotrichum lateriflorum (Aster lateriflorus) has flowering heads that are smaller (4-5 mm high), and 9-14 ray flowers (white to pale purple). This is also a plant typically found in dry habitats. Symphyotrichum puniceum (Aster puniceus) has larger flowering heads (6-12 mm high), and 30-60 ray flowers (usually blue, but sometimes ranges to rose or white). This plant also has more numerous leaves which clasp at the base, and stems with long hairs. There are reported hybrids between Symphyotrichum boreale and both Symphyotrichum lanceolatus and Symphyotrichum punicum. These exhibit characters intermediate between the parents.

Best Time to See

This aster may be flowering between mid-July through early October, although most plants have finished blooming by early September. Since this plant is likely overlooked, surveys should be conducted during the peak blooming period (late July through August).

  • Vegetative
  • Flowering
  • Fruiting

The time of year you would expect to find Northern Bog Aster vegetative, flowering, and fruiting in New York.

Northern Bog Aster Images


Northern Bog Aster
Symphyotrichum boreale (Torr. & Gray) A. & D. Löve

  • Kingdom Plantae
    • Phylum Anthophyta
      • Class Dicotyledoneae (Dicots)
        • Order Asterales
          • Family Asteraceae (Aster Family)

Additional Common Names

  • Bog Aster
  • Boreal Aster
  • Northern Aster
  • Rush Aster
  • Rush-like Aster


  • Aster borealis (Torr. & Gray) Prov. [Name used by many sources including Gleason and Cronquist (1991).]
  • Aster junciformis Rydb.
  • Aster laxifolius var. borealis Torr. & A. Gray

Additional Resources

Best Identification Reference

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

Other References

Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

Gleason, Henry A. 1952. The New Britton and Brown Illustrated Flora of the Northeastern United States and Canada.

Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.

New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.

New York Natural Heritage Program. 2024. New York Natural Heritage Program Databases. Albany, NY.

Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.

Rhoads, Ann F. and Timothy A. Block. 2000. The Plants of Pennsylvania, an Illustrated Manual. University of Pennsylvania Press, Philadelphia, PA.

Robert H. Mohlenbrock. USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln, Nebraska Courtesy of USDA NRCS Wetland <>

Semple, John C., Stephen B. Heard and ChunSheng Xiang. 1996. The Asters of Ontario (Conpositae: Astereae): Diplactis Raf., Oclemena Greene, Doellingeria Nees and Aster L. (including Canadanthus Nesom, Symphyotrichum Nees and Virgulus Raf.).

Voss, E.G. 1996. Michigan Flora. Part III. Dicots (Pyrolaceae-Compositae). Cranbrook Institute of Science Bulletin 61 and Univ. Michigan Herbarium. Ann Arbor, Michigan. 622 pp.

Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research University of South Florida]. New York Flora Association, Albany, New York


About This Guide

Information for this guide was last updated on: January 22, 2009

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Symphyotrichum boreale. Available from: Accessed June 21, 2024.