Conium maculatum L., Apiaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: du shen

English: carrot-fern, cigue maculee, cigue tachetee, deadly hemlock, fool's parsley, hemlock, poison hemlock, poison parsley, spotted hemlock, spotted parsley

French: grande ciguë

Habit:  herb

Description:  "Erect annual or biennial, with foetid odour when crushed. Stems hollow, striate, up to 2-(3) m high, usually light green and purple spotted or blotched, sometimes tinged purplish or pink, particularly toward base. Leaves 2-4-pinnate; ultimate segments narrowly or broadly ovate to deltoid, pinnatisect or serrate, 5-40 mm long; petioles light green and purple blotched when mature; stem leaves similar to basal, but shortly petiolate and 1-3-pinnate. Umbels 1-8 cm in diameter; rays 4-16; bracts c. > 4-8, narrow-triangular, acuminate, reflexed; bracteoles 3-6, triangular, confined to outer side of umbellets. Flowers numerous, white, c. 2 mm in diameter. Fruit dark brown, 2.5-3 mm long; ribs slender, light brown, often crenulate"  (Webb et al., 1988; 122).

Description from Flora of China online.

Habitat/ecology:  "Grassland, forests, riparian habitats, freshwater wetlands.  This plant grows best in moist and fertile soils.  The plant can spread quickly in disturbed areas and is highly competitive, preventing the establishment of native grasses and forbs by shading and competing for space"  (Weber, 2003; p. 117).

In New Zealand, "waste places, riverbeds, palustral, forest margins"  (Webb et al., 1988; 122).  "In Chile this species grows in the following environmental conditions:  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"  (Chileflora).  In New South Wales, Australia, "weed of disturbed sites, often near stockyards, along roadsides and riverbanks, widespread"  (NSW PlantNET).

Propagation:  Seed

Native range:  Northern Africa, Europe, temperate Asia to western China and northern India (GRIN).

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. 552)
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. 552)

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 (2011)
Australia Australia (continental)	Queensland	introduced invasive	National Herbarium of New South Wales (2011)
Canada Province of British Columbia	Canada (British Columbia)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
Canada Canada	Canada (country)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
Chile (continental) Chile	Chile (Republic of)	introduced	Belov, Michail (2011)
China China	China (People's Republic of)	native	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2011) Xinjiang. "Forest margins, cultivated field margins".
Japan Japan	Japan (country)	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 187)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 122)
United States (west coast) United States (west coast states)	USA (Oregon)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Washington)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	United States (other states)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (continental except west coast) United States (other states)	USA (Florida)	introduced	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

Control: 

Physical:  "Hand pulling plants may be effective, especially prior to seed set.  Spring mowing kills mature plants effectively; a second mow in late summer kills emerged seedlings and regrowth"

Chemical:  Effective post-emergent herbicides include 2,4-D ester, 2,4-D amine, or glyphosate applied in late spring"  (Weber, 2003; p. 117).

Additional information:
Photos and other information from Chileflora.

Additional online information about Conium maculatum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Conium maculatum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Conium maculatum may be available from the Germplasm Resources Information Network (GRIN).

References:

Atkinson, Rachel/Sawyer, John. 2011. Naturalized species in the Juan Fernández Archipelago, Chile. Unpublished spreadsheet.

Belov, Michail. 2011. Chileflora (online resource).

Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido. 2006. Nouveau catalogue de la flore vaculaire de l'archipel Juan Fernández (Chile) [Nuevo catálogo de la flora vacular del Archipélago Juan Fernández (Chile)]. Acta Bot. Gallica 153(4):399-587.

Mito, Toshikazu/Uesugi, Tetsuro. 2004. Invasive alien species in Japan: the status quo and the new regulation for prevention of their adverse effects. Global Environmental Research 8(2)/2004: 171-191.

National Herbarium of New South Wales. 2011. PlantNet: New South Wales Flora online. The Plant Information Network System of the Botanic Gardens Trust Version 2.0. Online resource.

U. S. Government. 2011. Integrated Taxonomic Information System (ITIS) (on-line resource).

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. 1988. Flora of New Zealand, Volume IV: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.

Weber, Ewald. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. 548 pp.

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).