Tagetes minuta L., Asteraceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  yes

Risk assessment results:  High risk, score: 20 (Go to the risk assessment)

Common name(s): [more details]

English: Aztec marigold, Mexican marigold, Muster John Henry, dwarf marigold, khaki-bush, stinking Roger, stinkweed, wild marigold

Hawaiian: ‘ōkole‘oi‘oi

Spanish: chinchilla enana, quinchihue

Habit:  herb

Description:  "A strongly aromatic annual herb, growing to 120 cm or more tall; stems with longitudinal channels or grooves, branching in large plants, pale brownish to reddish; leaves cauline, to 20 cm long, opposite on the main stem but often alternate on the branches of the inflorescence, deeply pinnafid with 9 to 17 finely serrated lobes; lobes lanceolate to narrowly elliptic, up to 5 cm long, 5 mm wide, dark green; sunken oil glands scattered especially along edges of leaves and on either side of the central vein of each lobe; inflorescence composed of terminal, cylindrical, narrow, shortly stalked flower heads, up to 12 mm long, 2 mm wide; in congested corymbs; containing 4 florets; florets 2 yellow tubular or disc and 2 cream ligulate or ray; involucral bracts joined with five short lobes above, smooth; fruit an achene, black, 5 to 8 mm long, .6 mm wide, spindle-shaped, flattened, sparsely covered with short brown hairs; apex with 4 pointed scales, one longer than the others; pappus a few awn-like bristles of various lengths.  The distinguishing characteristics of this weed are the grooved stems, its strong aromatic scent, deeply divided leaves and the variable length of bristles in the pappus"  (Holm et al., 1997; p. 824).

"Foetid annual herbs 2-10 dm tall, glabrous. Leaves pinnately compound, leaflets 9-17, linear-lanceolate, margins serrate. Heads numerous, usually in flat-topped cymes; involucre cylindrical, 8-12 mm high, apex 3-5-toothed; ray florets usually 3 per head, rays 1-2 mm long; disk florets usually 3-5 per head, corollas ca 2.5 mm long; longer pappus scales 2-3 mm long, the others ca 1 mm long. Achenes black, flattened, 6-8 mm long" (Wagner et al., 1999; p. 360).

Habitat/ecology:  "Coastal areas, disturbed places.  The species establishes readily in disturbed sites and can form dense populations after a fire or when forets are cut and burned.  The large size and dense growth makes it highly competitive to native plant species"  (Weber, 2003; p. 427).

In Hawai‘i, "naturalized primarily in subalpine forest and shrubland" (Wagner et al., 1999; p. 360). "This noxious, rapidly growing herb forms a dense ground cover at higher elevations. The plant is confined to dry and mesic areas on Mauna Kea between 1,700-3,000 m." (U. Hawai‘i Dept. of Botany).

Propagation:  "It is a prolific seed producer and seeds are dispersed by attaching to animals"  (Weber, 2003; p. 427).  "The seeds cling to hair and are dispersed by domesticated and feral animals" (U. Hawai‘i Dept. of Botany).

Native range:  South America, cultivated and naturalized elsewhere (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 8) "An uncommon but locally frequent weed of broken ground". Voucher cited: W.R. Sykes NI 594 (CHR)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 360) Voucher cited: Ewart III 279 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 360) Cultivated?
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced	MacKee, H. S. (1994) (p. 38) Vouchers cited: Franc 1758A, Däniker 1684, MacKee 15248, MacKee 23630, MacKee 34966, MacKee 41509

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	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 822)
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 822) Naturalized
Central America Central America (Pacific rim)	Guatemala (Republic of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 826)
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 190)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 290) "Cultivated land, waste places".
South America (Pacific rim) South America (Pacific rim)	Chile (Republic of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 827)
South America (Pacific rim) South America (Pacific rim)	Colombia		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 822)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)		Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 822)
Thailand Thailand	Thailand (Kingdom of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 822)
United States (west coast) United States (west coast states)	USA (California)	introduced	Munz, P. A./Keck, D. D. (1959) (p. 1160)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
British Indian Ocean Territory Chagos Archipelago	Diego Garcia Island	introduced cultivated	Topp, J. M. W. (1988) (p. 9) Tagetes sp.

Control: 

Physical:  "Plants can be removed manually"  (Weber, 2003; p. 427).

Chemical:  "An effective herbicide to control large infestations is paraquat.  Cutting before flowers open prevents seed formation"  (Weber, 2003; p. 427).  "Probably sensitive to triclopyr and perhaps to other hormone-type herbicides"  (Motooka et al., 2003).