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Montana Field Guide

Montana Field Guides

Alkali-marsh Ragwort - Senecio hydrophilus

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Species of Concern
Native Species

Global Rank: G5
State Rank: S3
(see State Rank Reason below)
State Threat Score: No Known Threats
C-value: 5

Agency Status


External Links

State Rank Reason (see State Rank above)
Senecio hydrophilus is present in alkaline habitats within a portion of southwest Montana. Plants are not that common, and occur in low-elevation wetlands that can be victum to dewatering.
  • Details on Status Ranking and Review
    Alkali-marsh Ragwort (Senecio hydrophilus) Conservation Status Review
    Review Date = 11/14/2016
    View State Conservation Rank Criteria
    Range Extent

    ScoreE - 5,000-20,000 sq km (~2,000-8,000 sq mi)

    Area of Occupancy

    ScoreD - 6-25 4-km2 grid cells

    Number of Populations

    ScoreB - 6 - 20

    Number of Occurrences or Percent Area with Good Viability / Ecological Integrity

    ScoreB - Very few (1-3) occurrences with excellent or good viability or ecological integrity

    Long-term Trend

    ScoreU - Unknown


    ScoreU - Unknown


    ScoreD - Low

    CommentThreat categories include: Dams & water management/use.

    Intrinsic Vulnerability

    ScoreU - Unknown

General Description
Plants: Perennial (possibly biennial), with the sea-green herbage conspicuously glaucous (McGregor et al. 1986), particularly on the stem, and glabrate. Stems often loosely clustered (Cronquist et al. 1994), erect, hollow, 40–100 cm (Lesica 2012), ascending from a short caudex with thick, fibrous, unbranched roots (McGregor et al. 1986).

Leaves: Thick and somewhat succulent (Cronquist et al. 1994); basal and lower stem leaves long-petiolate, pinnately-veined, the blades somewhat elliptic, oblanceolate (McGregor et al. 1986) or lanceolate, smooth-margined or slightly serrate, 2–20 cm in length (Lesica 2012), and 2-8(10) cm in width, length approximately twice the width; petiole similar in length to the blade; middle and upper stem leaves becoming reduced above in progressive fashion until sessile and bract-like (McGregor et al. 1986).

Inflorescence & Heads: Inflorescence a compound, flat-topped cyme (center flower blooming first) (McGregor et al. 1986) of 15 to 50 heads. Heads usually discoid (radiate); involucres 7–10 mm high; phyllaries 8 to 13 (Lesica 2012), of equal size and in a single series (McGregor et al. 1986), glabrous, sometimes black-tipped (Lesica 1986),

(Lesica's contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

Flowers July – August (McGregor et al. 1986).

Species Range
Montana Range Range Descriptions


Range Comments
BC south to CA, NV, UT, CO and SD (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 34

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Wet meadows in valleys and foothills (Lesica 2012), up to 8531 ft, withstanding alkali and standing water (Cronquist et al. 1994).

(Lesica's contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) in California tested the potential of using a South African moth, Digitivalva delaireae, as a biological control agent for Cape- or German-ivy, Delairea odorata, which is a South African plant that has become invasive in many western states of the U.S. Alkali-marsh ragwort (a close relative of Cape-ivy) and 36 other Asteraceae species native to the Continental U.S. were tested. Alkali-marsh ragwort was the only test species that experienced damage from the moth. When the insect had no other choice of plant species, a median of 30% of alkali-marsh ragwort’s leaves were damaged from leaf mining. This fell to 2.1% when insects were offered a choice of alkali-marsh ragwort or Cape-ivy. Adult moths also laid their eggs on alkali-marsh ragwort, but no pupation or stem-boring occurred (Mehelis et al. 2015).

The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius, Bombus flavifrons, Bombus frigidus, Bombus huntii, Bombus melanopygus, Bombus mixtus, Bombus sylvicola, Bombus occidentalis, Bombus insularis, Bombus suckleyi, Bombus flavidus, and Bombus kirbiellus (Schmitt 1980, Thorp et al. 1983, Mayer et al. 2000, Wilson et al. 2010, Pyke et al. 2012, Koch et al. 2012, Williams et al. 2014).

Reproductive Characteristics
Flowers & Fruit: Rays approximately 5, if present (Lesica 2012), fertile, yellow; ligules 3-8 mm in length; disk flowers perfect and fertile (McGregor et al. 1986), 5–6 mm long. Achenes smooth, 2–4 mm in length (Lesica 2012) crowned with pappus consisting of long, white and finely-barbed hairs (McGregor et al. 1986).

(P. Lesica's contribution adapted from Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)

Threats or Limiting Factors
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).

  • Literature Cited AboveLegend:   View Online Publication
    • Cronquist, A. 1994. Vol.5, Asteraceae. In: A. Cronquist, N. H. Holmgren, J. Holmgren, J. Reveal, and P. K. Holmgren, eds. Intermountain Flora, Vascular Plants of the Intermountain West, USA. New York Botanical Garden, Bronx, NY.
    • Koch, J., J. Strange, and P. Williams. 2012. Bumble bees of the western United States. Washington, DC: USDA Forest Service, Pollinator Partnership. 143 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Mayer, D.F., E.R. Miliczky, B.F. Finnigan, and C.A. Johnson. 2000. The bee fauna (Hymenoptera: Apoidea) of southeastern Washington. Journal of the Entomological Society of British Columbia 97: 25-31.
    • McGregor, R.L. (coordinator), T.M. Barkley, R.E. Brooks, and E.K. Schofield (eds). 1986. Flora of the Great Plains: Great Plains Flora Association. Lawrence, KS: Univ. Press Kansas. 1392 pp.
    • Mehelis, C.N., J. K. Balciunas, A.M. Reddy, L.Van Der Westhuizen, S.Neser, and P.J. Moran. 2015. Biology and host range of Digitivalva delaireae (Lepidoptera: Glyphipterigidae), a candidate agent for biological control of Cape-ivy (Delairea odorata) in California and Oregon. Environmental Entomology 44(2):260-276.
    • Pyke, G.H., D.W. Inouye, and J.D. Thomson. 2012. Local geographic distributions of bumble bees near Crested Butte, Colorado: competition and community structure revisited. Environmental Entomology 41(6): 1332-1349.
    • Schmitt, J. 1980. Pollinator foraging behavior and gene dispersal in Senecio (Compositae). Evolution 34: 934-943.
    • Thorp, R.W., D.S. Horning, and L.L. Dunning. 1983. Bumble bees and cuckoo bumble bees of California (Hymenoptera: Apidae). Bulletin of the California Insect Survey 23:1-79.
    • Williams, P., R. Thorp, L. Richardson, and S. Colla. 2014. Bumble Bees of North America. Princeton, NJ: Princeton University Press. 208 p.
    • Wilson, J.S., L.E. Wilson, L.D. Loftis, and T. Griswold. 2010. The montane bee fauna of north central Washington, USA, with floral associations. Western North American Naturalist 70(2): 198-207.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Ament, R.J. 1995. Pioneer Plant Communities Five Years After the 1988 Yellowstone Fires. M.Sc. Thesis. Bozeman, MT: Montana State University. 216 p.
    • Culver, D.R. 1994. Floristic analysis of the Centennial Region, Montana. M.Sc. Thesis. Montana State University, Bozeman. 199 pp.
    • Jones, W. W. 1901. Preliminary flora of Gallatin County. M.S. Thesis. Bozeman, MT: Montana State College. 78 pp.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
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Citation for data on this website:
Alkali-marsh Ragwort — Senecio hydrophilus.  Montana Field Guide.  .  Retrieved on , from