Hypochoeris radicata L., Asteraceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: flatweed, gosmore, hairy cat's ear

French: chicorée-pays

Habit:  herb

Description:  "A slender, erect, branching plant, 1 to 2-1/2 feet high.  Stem slender, smooth, almost free of leaves.  Leaves clustered at the base of the plant, 3 to 5 inches long, 1/4 to 1/2 inch wide, paddle-shaped, on long leafstalk, covered with hairs on both surfaces, margin smooth, mid-rib prominent.  Flower heads yellow, 3/4 to 1 inch across, on branching, leafless stalks, each flower with a narrow, pointed, chaffy scale at its base; heads enclosed by scales about 1/2 inch long, the outer ones short, inner bracts longer, sparsely clothed with hairs.  Fruit 1/4 inch long, rough, with slender neck; chaff or fruit-scale as long as the fruit and its bristles"  (Haselwood, 1966; p. 422).

Habitat/ecology:  This small rosette herb favors higher elevations.  It has a deep, succulent taproot favored by feral pigs, which dig up large areas searching for the roots (Smith, 1985; p. 192).  In Hawai‘i, "naturalized and often common, usually in wet but also relatively dry, disturbed sites, 1,100-2,800 m"  (Wagner et al., 1999; p. 327). In New Zealand, "pasture, grassland, lawns, sand dunes, roadsides, riverbeds, waste ground, stony ground, railway ballast, scrub and damaged forest, swamps, up to 1400 m" (Webb et al., 1988; p. 334).

Propagation:  Seeds are produced in large numbers and dispersed by wind. It regenerates rapidly from the crown of the taproot after fire (Smith, 1985; p. 192).

Native range:  Mediterranean region.

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. 206)
Australia (Pacific offshore islands) Lord Howe Island	Lord Howe Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 18) "A weed of grassland". Vouchers cited: J. Pickard 2833 (NSW), A.N. Rodd 1811 (NSW), J.D. McComish 202 (NSW)
Australia (Pacific offshore islands) Norfolk Islands	Norfolk Island	introduced invasive	Orchard, Anthony E., ed. (1994) (p. 8) A weed of grassland"A weed of grassland". Vouchers cited: W.R. Sykes NI 207 (CHR), W.R. Sykes NI 372 (CHR), W.R. Sykes NI 625 (CHR)
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 327)
State of Hawaii Hawaiian Islands	Kaho‘olawe Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 327)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 327)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 327)
State of Hawaii Hawaiian Islands	Lehua Island	introduced invasive	Wood, K. R./LeGrande, Maya (2006) (p. 20) Voucher cited: Flynn et al. 4859 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 327)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 327)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Staples, George W./Imada, Clyde T./Herbst, Derral R. (2002) (p. 6) Voucher cited: R. Heu s.n. (BISH 662906)
New Zealand (offshore islands) Kermadec Islands	Kermadec Islands	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 334)
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced	Sykes, W. R. (1977) (p. 93) Present status unknown.

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	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Chile (continental) Chile	Chile (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 188-189)
Colombia Colombia	Colombia (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 188-189)
Japan Japan	Japan (country)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (pp. 188-189)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 334)

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	Lavergne, Christophe (2006) "Très envahissant"

Control: 

Physical:  "Scattered plants can be dug out, crowns must be removed to prevent regrowth".

Chemical:  "Effective herbicides are MCPA salts, or 2,4-D amine and esters"  (Weber, 2003; p. 211).

Additional information:
Additional online information about Hypochoeris radicata is available from the Hawaiian Ecosystems at Risk project (HEAR).

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

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

References:

Haselwood, E. L./Motter, G. G. 1983. Handbook of Hawaiian Weeds. Second edition, revised and expanded by Robert T. Hirano. University of Hawaii Press. 491 pp.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Lavergne, Christophe. 2006. List des especes exotiques envahissantes a La Reunion. Unpublished manuscript (Excel file). .

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.

Smith, Clifford W. 1985. Impact of Alien Plants on Hawai‘i's Native Biota. In: Stone, Charles P. and Scott, J. Michael, eds. Hawai‘i's terrestrial ecosystems: preservation and Management. Cooperative National Park Resources Studies Unit, University of Hawaii, Manoa.

Staples, George W./Imada, Clyde T./Herbst, Derral R. 2002. New Hawaiian plant records for 2000. In: Evenhuis, Neal L. and Eldredge, Lucius G., eds. Records of the Hawaii Biological Survey for 2000. Part 1: Articles. Bishop Museum Occasional Papers. 68:3-18.

Sykes, W. R. 1977. Kermadec Islands flora: an annotated checklist. New Zealand Department of Scientific and Industrial Research Bulletin 219, Wellington. 216 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2009. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

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).

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.

Wood, K. R./LeGrande, Maya. 2006. An annotated checklist and new island records of flowering plants from Lehua Islet, Ni‘ihau, Hawai‘i. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2004-2005. Part 1: Articles. Bishop Museum Occasional Papers 87:19-29.