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Montana Field Guide

Montana Field Guides

Common St. John's-wort - Hypericum perforatum

Noxious Weed: Priority 2B
Exotic Species (not native to Montana)

Global Rank: GNR
State Rank: SNA

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 0

External Links






 
General Description
Taprooted and rhizomatous. Stems 25–75 cm tall. Leaves lanceolate, 1–3 cm long, black-dotted on the margins. Flowers: sepals linear-lanceolate, 5–8 mm long; petals 8–14 mm long with black-dotted margins. Capsule 5–8 mm long with brown seeds (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Unknown/Undetermined
 


Range Comments
Introduced throughout much of temperate N. America; native to Europe (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 78

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Relative Density

Recency

 

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



Habitat
Grassland, open forest, pastures, roadsides; valleys, montane (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

References
  • 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.
    • Morris, M. S., and J. Meuchel. 1956. The problem of St. Johnswort: a noxious plant in western Montana. Montana For. And Cons. Exp. Sta., School of For., University of Montana, Missoula. Bull. No.4. 8 pp.
    • Nelson, H.S. 1955. The phenology of goatweed, Hypericum perforatum in relation to the behavior of goatweed beetles, Chrysolina gemellata and C. hyperici, in western Montana. M.S. thesis. Montana State University, Missoula. 45 pp.
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Citation for data on this website:
Common St. John's-wort — Hypericum perforatum.  Montana Field Guide.  .  Retrieved on , from