Common St. John's-wort - Hypericum perforatum
Klamath Weed, Common St. Johnswort
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)
Introduced throughout much of temperate North America; native to Europe (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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(Observations spanning multiple months or years are excluded from time charts)
- 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.