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Giant Helleborine - Epipactis gigantea

Species of Concern
Native Species

Global Rank: G4
State Rank: S2S3
(see State Rank Reason below)

Agency Status
MNPS Threat Rank: 2
C-value: 8

External Links

State Rank Reason (see State Rank above)
Known from several dozen occurrences across western and southern Montana where it is associated with seeps and springs, fens, and thermal waters. Several sites are likely extirpated, while others are known only from historical collections. National Forest, state and private lands all host significant populations. The species is primarily vulnerable to hydrologic changes and development.
  • Details on Status Ranking and Review
    Giant Helleborine (Epipactis gigantea) Conservation Status Review
    Review Date = 01/07/2013
    View State Conservation Rank Criteria
    Population Size

    Score1-2 - Small to Moderate. Population size is imprecisely known but is believed to be >2,000 individuals and <100,000 individuals.

    CommentBased upon available estimates at known populations, it appears likely that total population in Montana is > 10,000 plants though estimates are too imprecise to be certain.

    Range Extent

    Score1 - Peripheral, Disjunct or Sporadic Distribution in MT: Widespread species that is peripheral, disjunct or sporadically distributed within MT such that it occurs in <5% of the state (<7,500 sq. miles or the combined area of Beaverhead and Ravalli Counties) or is restricted to 4-5 sub-basins.

    Area of Occupancy

    Score1 - Moderate: Generally occurring in 11-25 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    Score2 - High: Species is restricted to a highly specialized and limited habitat and is typically dependent upon unaltered, high-quality habitat (C Values of 8-10).


    Score1-2 - Minor to Moderate Declines:

    CommentTrend data are largely unavailable though small declines have likely taken place or can be expected to occur in the near future.


    Score1-2 - Medium to High.

    CommentSome populations near roadsides or at warm springs have a high potential to be negatively impacted.

    Intrinsic Vulnerability

    Score2 - High Vulnerability: Very specific biological attributes, unusual life history characteristics or limited reproductive potential makes the species highly susceptible to extirpation from stochastic events or other adverse impacts to its habitat and very slow to recover.

    Raw Conservation Status Score

    Score 9 to 12 total points scored out of a possible 19.

General Description
Giant Helleborine is a large perennial herb with leafy stems that are 30-100 cm tall and which arise from short rhizomes. The leaves are without petioles and up to 20 cm long; the lower are ovate, while the upper are lance-shaped. The herbage is rough to the touch or smooth and glabrous. The numerous flowers are borne singly in a long, narrow, leafy-bracted inflorescence located at the tops of the stems. The lance-shaped sepals are green with brownish stripes and approximately 15 mm long. The upper two petals are shorter and broader than the sepals. The lower petal is sac-like and longer and more reddish than the sepals. The nodding capsule is elliptic and bears many thousands of tiny seeds.

Flowering in late June-early August.

Diagnostic Characteristics
The tall stems with reddish flowers in the leaf axils make this species one of our most distinctive orchids. It is not easily confused with any other species.

Species Range
Montana Range


Range Comments
BC south to CA, AZ, NM, TX, Mexico (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 92

(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)

Stream banks, lake margins, fens with springs and seeps, often near thermal waters.

  • Additional ReferencesLegend:   View Online Publication
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    • Allen, D.R. 1982. Epipactis gigantea. American Orchid Society Bulletin 51(10): 1038-1040.
    • Berg, Ken, and Roxanne Bittman. 1988. Rediscovery of the Humboldt milk-vetch. Fremontia. 16(1):13-14.
    • Brunton, D.F. 1986. Status of the giant helleborine, Epipactis gigantea (Orchidaceae), in Canada. The Canadian Field-Naturalist 100(3): 414-417.
    • Burns-Balogh, P., D. L. Szlachetko, and A. Dafni. 1987. Evolution, pollination, and systematics of the tribe Neottieae (Orchidaceae). Plant Systematics and Evolution 156: 91-115.
    • Idaho Native Plant Society. 1993. Federal candidate (C1 and C2) and listed rare plants of Idaho. unpaginated.
    • 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., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Mantas, M. 1993. Ecology and reproductive biology of Epipactis gigantea Dougl. (Orchidaceae) in northwestern Montana. M.S. thesis. University of Idaho. 73 pp.
    • Rare and Endangered Plants Technical Committee, Idaho Natural Areas Council. 1981. Vascular Plant Species of Concern in Idaho. University of Idaho, College of Forestry, Wildlife and Range Sciences, Bulletin No. 34. 161 pp.
    • Schassberger, L.A . 1988. Status review of Epipactis gigantea, USDA Forest Service, Region 1, Flathead National Forest. Unpublished report. Montana Natural Heritage Program, Helena, MT 42 pp.
    • Vanderhorst, J.P. and B.L. Heidel. 1995. Sensitive plant survey in the Tobacco Root Mountains, Madison County, Montana. Unpublished report to the Beaverhead and Deerlodge National Forests. Montana Natural Heritage Program. Helena, MT. 66 pp. plus appendices.
    • Vij, S. P. and G. C. Gupta. 1975. Cytological investigations into W. Himilayan Orchidaceae 1. Chromosome numbers and karyotypes of taxa from Kashmir. Cytologia 40:613-621.
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Giant Helleborine — Epipactis gigantea.  Montana Field Guide.  .  Retrieved on , from