Hypericum perforatum L., Hypericaceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Hawai‘i/Pacific:  High risk, score: 12 (Go to the risk assessment)
Risk assessment from the Government of Queensland, Australia (PDF format).

Other Latin names:  Hypericum vulgare Lam.

Common name(s): [more details]

Chinese: guan ye lian qiao

English: Klamath weed, St. John's-wort, Tiptonweed, goatweed, perforate St. John's-wort, racecourseweed

French: herbe à mille trous, millepertuis commun

Spanish: corazoncillo, hierba de San Juan

Habit:  herb

Description:  "Rhizomatous perennial herbs; stems 1 to several, erect, becoming somewhat woody toward base, 5-10 dm long, black-dotted.  Leaves linear to elliptic or oblanceolate, primary ones 10-30 mm long, 3-16 mm wide, usually black-dotted.  Flowers in paniculate cymes; sepals connate at base, the lobes lanceolate, 3-5 mm long, glandular punctate; petals obovate, 5-8 mm long, black-dotted along margins; stamens numerous, in 3 clusters; styles 3 (4).  Capsules ovoid, 7-8 mm long.  Seeds dark brown, cylindrical, ca. 1 mm long, the surface pitted"  (Wagner et al., 1999; p. 546).

Habitat/ecology:  "Grass- and woodland, riverbanks, disturbed areas.  This plant forms extensive and dense colonies where invasive, eliminating native vegetation.  Seedlings are sensitive to competition but established plants compete successfully with native forbs and grasses.  The weed cannot survive in densely shaded areas"  (Weber, 2003; p. 210).  "In Chile this species grows in the following environmental conditions:  Medium altitude up to the timber line; low altitude, interior valleys; coastal mountains, 500-2000 m; coastal areas, 0-500 m.  Somewhat dry areas where the drought may last 3-5 months, precipitations of 400-800 mm. are concentrated in winter.  Fully exposed to the sun, level areas or slopes facing north; some shadow, some protection against direct sunlight, some shadow from vegetation, filtering about 20-40% of light (Chileflora).

Propagation:  "Quick maturing, relatively long-lived, produces many long-lived seeds and a tough rhizome system. Seeds spread by wind (minor), and possibly livestock. Rhizomes spread by soil and water movement and greenwaste dumping. Sources of seed and rhizomes for new infestations include roadsides, pasture, wasteland, riverbeds and gardens. Increasingly cultivated as a medicinal herb"  (Weedbusters New Zealand).

Native range:  "Native to Eurasia, widely naturalized" (Wagner et al., 1999; p. 546).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 554)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más Afuera (Alejandro Selkirk Island)	introduced invasive	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 554)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 546) Voucher cited: Fosberg 42087 (BISH)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	New South Wales	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
Australia Australia (continental)	Australia (continental)	introduced invasive	National Herbarium of New South Wales (2013) South Australia, Tasmania, Victoria Naturalised
Australia Australia (continental)	Queensland	introduced invasive	National Herbarium of New South Wales (2013) Naturalised
British Columbia (province of Canada) Province of British Columbia	Canada (British Columbia)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Open woodlands, meadows, grasslands, and steppes, riverbanks, stony and grassy slopes, roadsides, in dry or well-drained habitats; 100-2800 m. Gansu, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Yunnan.
Japan Japan	Japan	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 183) var. perforatum and var. angustifolium DC.
Mexico Mexico	Mexico (United Mexican States)	introduced invasive	National Herbarium of New South Wales (2013) Naturalized
New Zealand New Zealand	New Zealand (country)	introduced invasive	Owen, S. J. (1997)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 544) "A particularly troublesome weed in tussock grasslands, also very common in pastures, roadsides, riverbeds, waste places and in many modified open communities".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)	introduced invasive	Belov, Michail (2013)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
La Réunion (France) La Réunion Island	La Réunion Island	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Comments:  "A serious weed, and its potential for photosensitization poses a threat to livestock in many parts of the world" (Wagner et al., 1999; p. 546).

Control:  "Can resprout from rhizomes and seed bank reinfests bared sites  Can be left in regenerating bush and shrubland, as will disappear as light levels fall"  (Weedbusters New Zealand).

Physical:  "Seedlings and smaller plants can be hand pulled or dug out, crowns and rhizomes must be removed.  Repeated defoliation can reduce the plant's density".

Chemical:  "Effective herbicides are 2,4-D, glyphosate, or picloram.  Bare ground resulting from control measures is likely to be colonized by emerging seedlings"  (Weber, 2003; p. 210).

"1. Weed wipe (spring-summer only): glyphosate (333ml/L + penetrant) or metsulferon-methyl 600g/kg  (5g/L+ penetrant). 2. Spray (spring-summer only): glyphosate (10ml/L) or metsulferon-methyl 600g/kg (1g/10L).

Biological:  Chrysolina beetle"  (Weedbusters New Zealand).