Search Field Guide
Advanced Search
Montana Field Guide

Montana Field Guides

Weak Groundsel - Senecio debilis
Other Names:  Packera debilis


Global Rank: G4
State Rank: S3S4
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 8

External Links






State Rank Reason (see State Rank above)
Senecio debilis is fairly common in wet alkaline meadows in four counties of southwest Montana. More current data on population sizes and distributions is needed before warranting it as a Species of Concern.
  • Details on Status Ranking and Review
    Weak Groundsel (Senecio debilis) Conservation Status Review
    Review Date = 11/14/2016
    View State Conservation Rank Criteria
    Population Size

    ScoreU - Unknown

    Range Extent

    ScoreF - 10,000 - 100,000 individuals

    Area of Occupancy

    ScoreD - 6-25 4-km2 grid cells

    Number of Populations

    ScoreC - 21 - 80

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

    ScoreC - Few (4-12) occurrences with excellent or good viability or ecological integrity

    Long-term Trend

    ScoreU - Unknown

    Trends

    ScoreU - Unknown

    Threats

    ScoreU - Unknown

    CommentThreats: Unknown/undetermined.

    Intrinsic Vulnerability

    ScoreC - Not intrinsically vulnerable

 
General Description
Plants: Perennial with a short, upright to ascending caudex and seldom-branching fibrous roots. Stems 1 to several (Cronquist et al. 1994), erect, 10–50 cm (Lesica 2012). Herbage glabrous or softly woolly when young, by flowering time glabrous or only sparsely arachnoid in leaf axils (Hitchcock et al. 1955).

Leaves: Basal leaves thick and slightly succulent, occasionally on individual short shoots (Cronquist et al. 1994); the blades ovate or obovate, crenate, 1–6 cm in length (Lesica 2012), 1-3 cm in width; margins wavy, small-lobed, or subentire; petiole usually longer than the blade. Cauline leaves few, narrowing progressively up the stem and becoming sessile (Cronquist et al. 1994), deeply pinnately divided into several pairs of rounded lobes (Lesica 2012) with deep, wide sinuses (Cronquist et al. 1994).

Inflorescence & Heads: Inflorescence corymbiform with 3 to 15 heads (Lesica 2012), densely to somewhat openly arranged (Cronquist et al. 1994). Discoid heads bell-shaped; involucres 5–8 mm high; phyllaries 13 or 21, hairless, green (Lesica 2012).

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

Phenology
Flowers late June to mid-August (FNA 2006).

Diagnostic Characteristics
Senecio debilis and S. indecorus have similarities. However, the latter has more sharply-pointed leaf lobes and its leaves are not appreciably thick. It also seldom resides in areas of high alkalinity (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Present
 


Range Comments
MT, ID, WY and CO (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 33

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

Recency

 

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



Habitat
Moist, alkaline meadows in the valley and foothill zones (Cronquist et al. 1994; Lesica 2012).

(Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX.)

Reproductive Characteristics
Flowers & Fruit: Disk corollas 3–7 mm long (Lesica 2012), orangish (Cronquist et al. 1994); pappus of white capillary bristles. Achenes 1–2 mm long, glabrous (Lesica 2012).

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

References
  • 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.
    • Flora of North America Editorial Committee. 2006. Flora of North America North of Mexico. Vol. 20. Magnoliophyta: Asteridae, part 7: Asteraceae, part 2. Oxford Univ. Press, New York. xxii + 666 pp.
    • Hitchcock, C.L. 1955. Compositae. In C.L. Hitchcock, A. Cronquist, M. Ownbey, and J.W. Thompson (eds.). Vascular Plants of the Pacific Northwest. Part 5. Seattle, WA: University of Washington Press. 343 pp.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Culver, D.R. 1993. Sensitive plant species inventory in the Centennial Valley, Beaverhead County, Montana. Unpublished report to the Butte District, Bureau of Land Management. Montana Natural Heritage Program, Helena, 42 pp. plus appendices.
    • Lesica, P. 1990. Vegetation and sensitive plant species of wetlands associated with geothermal areas in the greater Yellowstone ecosystem in Montana. Unpublished report on file at the Montana Field Office, The Nature Conservancy, Helena. 9 pp.
    • Lesica, P. 1994. The distribution of plant community diversity associated with glacial wetlands in the Ovando Valley, Montana. [Unpublished report.] The Nature Conservancy, Montana Field Office, Helena. 26 pp.
    • Vanderhorst, J.P. and P. Lesica. 1994. Sensitive plant survey in the Tendoy Mountains, Beaverhead County, Montana. Unpublished report to the Bureau of Land Management, Butte District. Montana Natural Heritage Program, Helena, MT. 59 pp. plus appendices.
  • Web Search Engines for Articles on "Weak Groundsel"
  • Additional Sources of Information Related to "Dicots"
Login Logout
Citation for data on this website:
Weak Groundsel — Senecio debilis.  Montana Field Guide.  .  Retrieved on , from