Northern Twayblade - Listera borealis
(see State Rank Reason below)
MNPS Threat Rank
State Rank Reason (see State Rank above)
Few occurrences documented for the state. It appears likely that this species is more abundant than current observations document. Habitat for the species does not appear to be uncommon, nor particularly threatened. The species is probably overlooked and under-collected. However, population numbers are likely to be quite small, as observations for the species thus far have only noted a few plants, at most, at each site.
- Details on Status Ranking and Review
Score1 - Moderate: Generally 10,000-100,000 individuals.
CommentPoorly documented but estimated to be approximately 10,000+ plants.
Score0 - Widespread species within Montana (occurs in 5% or more of the state or generally occurring in 6 or more sub-basins.) as well as outside of Montana.
Area of Occupancy
Score0-1 - Moderate to High. Occurs in >10 Subwatersheds (6th Code HUC’s), though the species' distribution is not sufficiently documented to place it within one class.
Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).
Score0-1 - Stable to Minor Declines:
CommentActual trends are unknown, though habitat is laregely stable and there is no indication that significant declines have occurred.
Score1 - Medium: 11-30% of the populations are being negatively impacted or are likely to be impacted by one or more activities or agents, which are expected to result in decreased populations and/or habitat quality and/or quantity.
CommentThough impacts may be occurring or likely at some locations, the magnitude or immediacy of threats to the species or its habitat are not significant at this time.
Score1-2 - Moderate to High Vulnerability.
Raw Conservation Status Score
4 to 7 total points scored out of a possible 19.
Stems 5–15 cm, glandular-pubescent above. Leaves ovate, 2–4 cm long. Inflorescence of 3 to 12 flowers; bracts 1–3 mm long. Flowers: sepals 4–5 mm long, linear-lanceolate; lip petal declined but not pendent, 7–11 mm long, broadly oblong with 2 rounded lobes at the tip. Capsule ellipsoid, ca. 8 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX)
This species is similar to L. convallarioides, which has an abrupt narrowing at the base of the lip, and it's sepals are reflexed backward.
AK to NL south to WA, UT and CO (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Grows in seepy, marshy places along cold-air drainages, often where calcareous.
Ecological Systems Associated with this Species
- Additional ReferencesLegend: View Online Publication
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- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.