Pacific Island Ecosystems at Risk (PIER)

  [   PIER species lists  ]   [   PIER home  ]

Ageratina adenophora
(Spreng.) R.M.King & H.Rob., Asteraceae
Click on an image for links to BIGGER PICTURES


Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Eupatorium adenophorum Spreng.; Eupatorium glandulosum Michx.; Eupatorium trapezoideum Kunth

Common name(s): [more details]

Chinese: po huai cao

English: catweed, croftonweed, hemp agrimony, Mexican devil, pamakani, sticky agrimony, sticky snakeroot, white thoroughwort

Hawaiian: Maui pāmakani, pāmakani haole

Habit:  herb

Description:  "Perennial coarse herbs to 1.5 m tall; stems often purple, terete, erect, glandular puberulent. Leaves opposite, median ones larger, ovate-deltoid, 7-10 cm long, 4-7 cm wide, apex acuminate, base obtuse to very broadly cuneate or truncate, sparsely pilose on both surfaces, 3-nerved, margins crenate, petiole 4-5 cm long, upper leaves gradually smaller toward inflorescence. Inflorescence of loose compound corymbs, heads ca. 6.5 mm long, 6 mm in diameter, peduncle 8-14 mm long, densely pubescent; involucre cylindric, ca. 3-4 mm long; bracts ca. 25, 3 or 4 seriate, outer ones narrowly lanceolate, inner ones narrowly oblong, apex acute, base obtuse, margins membranaceous, ciliate; florets ca. 70-80, white; receptacle glabrous, areolate. Achenes black, 1.5 mm long, 5-angular, glabrous. Pappus of 8-10 bristles, ca. 3.5 mm long"  (Digital Flora of Taiwan).

"Malodorous subshrubs; stems often purple, erect, usually 5-15 dm long, unbranched to branched, densely glandular puberulent and puberulent.  Leaves darker on upper surface, rhombic to deltate, 4-15 cm long, 1-6 (-8) cm wide, margins coarsely serrate, petioles usually 1-6 cm long.  Inflorescences strictly erect; involucral bracts 3-5 mm long, glandular puberulent; corollas white, ca. 3 mm long.  Achenes reddish brown, ca. 1.5 mm long." (Wagner et al., 1999; p. 254).

Description from the Flora of China online.
Description from the Flora of North America online.

Habitat/ecology:  "Dry to wet forests, river banks, swampy sites, grassland, disturbed places.  Dense stands eliminate native vegetation and prevent the regeneration of native plants"  (Weber 2003; p. 28).  "A highly invasive plant, tolerant of a wide range of conditions, common on roadsides and bushland edges, along watercourses, creeks, and in wetlands. Forms dense stands, prefers moist, nutrient-rich soil, is common in disturbed areas.  Capable of infesting intact bushland and displacing native plants; an increasing problem"  (Weeds of Blue Mountains bushland).

In Hawai‘i, "naturalized from relatively dry areas to wet forest, 600-2,000 m" (Wagner et al., 1999; p. 254). 

Propagation:  Seed.  "Seed production is enormous - 10,000 to 100,000 per year when mature. The seeds are very small, light, brown to black, with a 4mm "parachute" of white hairs, mid to late spring. Germination rates are high.  Seed is dispersed by wind and water over long distances, and is also moved by vehicles and machinery, and in clothing, soil and stockfeed. Also spread by garden dumping"  (Weeds of Blue Mountains bushland).

Native range:  Mexico (Wagner et al., 1999; p. 254); also cultivated and naturalized (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)
Lord Howe Island
Lord Howe Island introduced
Pickard, J. (1984) (p. 205)
Australia (Pacific offshore islands)
Lord Howe Island
Lord Howe Island introduced
invasive
Orchard, Anthony E., ed. (1994) (p. 18)
"A Central American adventive which is invading open areas in the forest and should be urgently controlled". Vouchers cited: G. Uhe 1284 (K), L.A.S. Johnson & A.N. Rodd 1307 (NSW), P.S. Green 1969 (K), R.D. Hoogland 8730 (NSW), J. Pickard 2766 (NSW)
French Polynesia
Society Islands
Tahiti Island introduced
invasive
Welsh, S. L. (1998) (p. 69)
Voucher cited: BRY 24873
State of Hawaii
Hawaiian Islands
Kaua‘i Island introduced
Wester, Lyndon (1992) (p. 127)
State of Hawaii
Hawaiian Islands
Lāna‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 254-255)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 254-255)
State of Hawaii
Hawaiian Islands
Moloka‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 254-255)
Voucher cited: Rock 6133 (BISH)
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 254-255)
Philippines
Philippine Islands
Philippine Islands   Waterhouse, D. F. (1993) (p. 63)
Philippines
Philippine Islands
Philippine Islands introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
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)
Australia (continental) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Australia
Australia (continental)
New South Wales introduced
invasive
Harley, Barbara (2009)
Australia
Australia (continental)
Queensland introduced
invasive
Queensland Herbarium (2002) (p. 1)
Cambodia
Cambodia
Cambodia (Kingdom of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
China
China
China (People's Republic of) introduced
invasive
Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
"Wet places or roadsides on slopes, forest margins; 900-2200 m. Introduced and naturalized".
China
China
China (People's Republic of) introduced
invasive
Li-ying, Li/Ren, Wang/Waterhouse, D. F. (1997) (pp. 172, 178)
Indonesia
Indonesia
Indonesia (Republic of)   Waterhouse, D. F. (1993) (p. 63)
Mexico
Mexico
Mexico (United Mexican States) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Negara Brunei Darussalam
Brunei
Brunei (Negara Brunei Darussalam)   Waterhouse, D. F. (1993) (p. 63)
New Zealand
New Zealand
New Zealand (country) introduced
invasive
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 205)
"Usually forest margins and clearings, waste places, scrubland, streamsides, rarely in swamps".
Taiwan
Taiwan Island
Taiwan Island introduced
Ching-I Peng, ed. (2013)
Thailand
Thailand
Thailand (Kingdom of)   Waterhouse, D. F. (1993) (p. 63)
United States (west coast)
United States (west coast states)
USA (California) introduced
invasive
U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)
Vietnam
Vietnam
Vietnam (Socialist Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized

Comments:  A declared noxious weed in the United States.

Control: 

Physical: "May be controlled by slashing, followed by ripping or plowing, then sowing desirable pasture species"  (Motooka et al., 2003).  "Dig or pull out small infestations. Expose roots"  (Weedbusters New Zealand).

Chemical: "Herbicides used to control this plant include glyphosate, 2,4-D amine, dicamba and MCPA, or triclopyr, applied in late summer when the plant is actively growing"  (Weber, 2003; p. 28). Susceptible to hormone-type herbicides and glyphosate"  (Motooka et al., 2003).

"1. Weed wipe (all year round): glyphosate (333ml/L); or metsulferon-methyl 600g/kg (2g/L).
2. Spray: glyphosate (20ml/L + penetrant). 
3. Spray: metsulferon-methyl 600g/kg (20g/100L (spraygun) or 5g/10L (knapsack)). Add penetrant in winter. Spray lightly, not to run off"  (Weedbusters New Zealand).

Biological:  "Successful biological control has been achieved in Hawai‘i by the introduction of the Trypetid gallfly, Procecidochares utilis, a species which has also caused considerable mortality in parts of Australia, South Africa, New Zealand and India" (Cronk & Fuller, 2001; p. 134).  In Hawai‘i, "no quantitative evaluations are available, but the fungus Entyloma compositarum (Basidiomycetes: Ustilaginales) is considered effective. Fungal infestation of plants during wet periods coupled with the impact of previously introduced insects has resulted in other plants invading monotypic stands and in some cases replacing them"  (Smith et al., 2002; p. 98).

Additional information:
Excerpt from the book "Weeds of Hawaii‘s Pastures and Natural Areas; An Identification and Management Guide" (Motooka et al., 2003). (PDF format).
Information from the Australian National Weed Strategy.
Photos and additional information at the Environment Bay of Plenty, New Zealand, web site of the Bay of Plenty Regional Council.
Fact sheet from the Government of Queensland, Australia. (PDF format).
Information and photos at Weeds of Blue Mountains bushland.
Information sheet from Weedbusters New Zealand.

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

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

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

References:

Ching-I Peng, ed. 2013. Digital flora of Taiwan (online resource).

Cronk, Q. C. B./Fuller, J. L. 2001. Plant invaders. Earthscan Publications, Ltd., London. 241 pp.

Harley, Barbara. 2009. Weeds of Blue Mountains bushland. (online resource).

Li-ying, Li/Ren, Wang/Waterhouse, D. F. 1997. The distribution and importance of arthropod pests and weeds of agriculture and forestry plantations in southern China. ACIAR, Canberra, Australia. 185 pp.

Motooka, Philip/Castro, Luisa/Nelson, Duane/Nagai, Guy/Ching, Lincoln. 2003. Weeds of Hawaii‘s Pastures and Natural Areas; An Identification and Management Guide. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. 184 pp.

Orchard, Anthony E., ed. 1994. Flora of Australia. Vol. 49, Oceanic islands 1. Australian Government Publishing Service, Canberra.

Pickard, J. 1984. Exotic plants on Lord Howe Island: Distribution in space and time, 1853-1981. J. of Biogeography 11:181-208.

Queensland Herbarium. 2002. Invasive Naturalised Plants in Southeast Queensland, alphabetical by genus. Modified from: Batianoff, George N. and Butler, Don W. (2002). Assessment of Invasive naturalized plants in south-east Queensland. Appendix. Plant Protection Quarterly 17, 27-34. 11 pp.

Smith, Clifford W./ Denslow, Julie/ Hight, Stephen. 2002. Proceedings of workshop on biological control of native ecosystems in Hawai‘i. Pacific Cooperative Studies Unit (University of Hawaii at Manoa, Department of Botany) Technical Report 129. 122 pages.

U.S. Dept. Agr., Agr. Res. Serv. 2013. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2013. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Waterhouse, D. F. 1993. The major arthropod pests and weeds of agriculture in Southeast Asia. The Australian Centre for International Agricultural Research, Canberra. 141 pp.

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.

Welsh, S. L. 1998. Flora Societensis: A summary revision of the flowering plants of the Society Islands. E.P.S. Inc., Orem, Utah. 420 pp.

Wester, Lyndon. 1992. Origin and distribution of adventive flowering plants in Hawai‘i. In: Stone, Charles P.; Smith, Clifford W. and Tunison, J. Timothy. Alien plant invasions in native ecosystems of Hawaii: Management and Research. University of Hawaii, Cooperative National Park Research Studies Unit, Honolulu. University of Hawaii Press. .

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2013. Flora of China (online resource).


Need more info? Have questions? Comments? Information to contribute? Contact PIER! (pier@hear.org)

  [   PIER species lists  ]   [   PIER home  ]

This page was created on 24 MAR 2005 and was last updated on 19 FEB 2013.