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Montana Field Guide

Montana Field Guides

Roundleaf Water-hyssop - Bacopa rotundifolia

Species of Concern

Global Rank: G5
State Rank: S3?
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank: 3
C-value: 7

External Links






State Rank Reason (see State Rank above)
A rare species known in Montana from only a few observations in the central and eastern portions of the state. However, the species is widely distributed and appears tolerant of brackish waters as well as some degree of nutrient enrichment. As such, it is unclear to what extent the species' viability is at risk in the state and whether it responds negatively to human-induced impacts to water quality. Additional populations of the species are likely to occur in Montana.
  • Details on Status Ranking and Review
    Roundleaf Water-hyssop (Bacopa rotundifolia) Conservation Status Review
    Review Date = 06/01/2012
    View State Conservation Rank Criteria
    Population Size

    Score1-3 - Very Small to Moderate: Population size is imprecisely known but is believed to be <100,000 individuals.

    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

    Score2 - Low: Generally occurring in 4-10 Subwatersheds (6th Code HUC’s).

    Environmental Specificity

    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).

    Trends

    ScoreNA - Rank factor not assessed.

    CommentPopulation trends are unknown, though species could potentially be introduced to some sites or increasing in numbers.

    Threats

    Score0-1 - Low to Medium.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 5 to 9 total points scored out of a possible 16 (Rarity factors and threats only).

 
General Description
Roundleaf Water-hyssop is a fibrous-rooted perennial herb with branched, succulent stems, 10-40 cm long, that float on the surface of the water and root in mud at the nodes. The broadly elliptic to circular leaves, 1-3 cm long, are sessile and opposite each other on the stems. Newer foliage is short and hairy. Flowers are borne on stalks, 5-20 mm long, arising from the axils of leaves. The cup-shaped, white flowers are 5-10 mm long and have 5 equal lobes above a united tube that is yellow inside. There are 4 small stamens. The calyx is composed of 5 separate sepals, one much broader than the others. Globose capsules, 3-6 mm high, contain numerous small seeds.

Phenology
Flowering and fruiting June-August.

Diagnostic Characteristics
Aquatic to emergent, glabrous, fibrous-rooted perennials. Stems prostrate, glabrous to puberulent, 5–25 cm, rooting at the lower nodes. Leaves opposite, sessile, obovate to orbicular, glabrous, 1–3 cm long. Inflorescence 1 to 4 pedicellate flowers at leaf nodes. Flowers: calyx 3–6 mm long, divided nearly to the base into 5 unequal lobes; corolla campanulate, white with a yellow throat, 5-lobed, barely irregular, 5–7 mm long; stamens 4; style 2-lobed. Capsule orbicular, 3–6 mm long, opening by 4 valves (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Present
 


Range Comments
MT to MN, south to CA, TX, LA and MS (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 7

(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
Muddy shores of ponds and streams in the valleys and on the plains.

Ecological Systems Associated with this Species

References
  • Additional ReferencesLegend:   View Online Publication
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    • Barrett, S.C.H., and J.L. Strother. 1978. Taxonomy and natural history of Bacopa (Scrophulariaceae) in California. Systematic Botany 3(4): 408-419.
    • Dolan, R. W. 2004. Conservation Assessment for Roundleaf water-hyssop (Bacopa rotundifolia (Michx.) Wettst.). USDA Forest Service, Eastern Region.
    • Heidel, B.L. 1994. Sensitive plant species survey in Garfield and McCone Counties, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, Montana. 58 pp. plus appendices.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
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Citation for data on this website:
Roundleaf Water-hyssop — Bacopa rotundifolia.  Montana Field Guide.  .  Retrieved on , from