Oxalis latifolia Kunth, Oxalidaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Ionoxalis vallicola Rose; Oxalis vallicola (Rose) R. Knuth

Common name(s): [more details]

English: broadleaf woodsorrel, fishtail oxalis, pink shamrock, purple-flowered oxalis, shamrock

French: oseille, trèfle

Spanish: acedera, acederilla, trebol, trebol de huerta, trebol de jardin, trebol falso

Habit:  herb

Description:  "A stemless perennial herb; taproot up to 6 cm long, carrot-like, waxy-white; bulbs found on top of taproot, 1 to 2 cm in diameter, composed of lanceolate scales, outer ones brown and papery, inner ones white, fleshy; bulbs form rhizomes up to 10 cm long with terminal bulbils 5 to 6 mm in diameter; petioles arise from bulb, erect, slender, glabrous, 10 to 25 cm long, bearing 3 smooth, distinctly triangular leaflets, 2 to 5 cm wide; leaflets about twice as wide as long, with smooth edges, rounded corners; apex notched up to one-third the length of leaflet; peduncle arises from leaf axil of bulb, 15 to 20 cm tall, usually exceeding petiole length; inflorescence 5 to 12 flowers borne in slender, drooping umbels, bluish-purple, pinkish-purple or purple-violet; flowers perfect; calyx of 5 oblong- lanceolate sepals 4 to 5 mm wide, each with two small orange glands at apex; corolla of 5 overlapping petals, twisted in bud, free, green below, purpled above, 12 to 15 mm long; stamens 10 in two series of 5 each in lower, middle or upper positions relative to stigma; ovary 5-locular with 5 styles; fruit rare, if present a longitudinal capsule, green until maturity, with small, oval, orange to dark yellow seeds 0.7 by 1 mm, with 2 longitudinal and several transverse ribs giving seed coat a wavy appearance.  This weed is recognized by the taproot below the scaly bulb, numerous bulbils formed on rhizomes, the notched, triangular leaflets and the purplish flowers with orange glands at the calyx apex"  (Holm et al., 1997; p. 550).

Description from Flora of Pakistan

Habitat/ecology:  Common in gardens, orchards, plantation crops, nurseries, and any intensely cultivated area.  Plants are shade tolerant. The weed grows in medium and heavy textured soils in Bolivia but is common in the light-textured, low organic matter soils of Mauritius (Holm et al., 1997; p. 550).  "Forests and forest edges, arable fields, waste places.  A variable species with regard to leaf shape.  Although mainly a weed of agroecosystems, it invasdes natural plant communities and crowds out native plants due to the dense stands"  (Weber, 2003; p. 293).

Propagation:  Most reproduction is vegetatively, through bulbs and bulbils.  When seeds are produced, they are "shot" 20 to 40 cm from the capsule when the valves split open  (Holm et al., 1997; pp. 551-552).

Native range:  United States (New Mexico) through Mexico and Central America to northern South America (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced invasive	Charles Darwin Foundation (2008)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 109) Voucher cited: MacKee 45742 Spontané
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 920) "A very bad weed of cultivated and waste ground, particularly in open places with loose soil but sometimes amongst taller vegetation".
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 548)

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. 548)
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 548)
Colombia Colombia	Colombia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Costa Rica Costa Rica	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
El Salvador El Salvador	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Guatemala Guatemala	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Honduras Honduras	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Indonesia Indonesia	Indonesia (Republic of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 548)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 920) "A very bad weed of cultivated and waste ground, particularly in open places with loose soil but sometimes amongst taller vegetation".
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Taiwan Taiwan	Taiwan Island	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 548)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (pp. 548, 550, 554)
Seychelles Seychelles Islands	Seychelles Islands	introduced	Weber, Ewald (2003) (p. 293)

Control: 

Physical:  "Repeated clipping reduces the vigor of this plant.  Covering plants with plastic or straw mulch can kill the plants, as does flooding".

Chemical:  "Effective herbicides are 2,4-D, diuron, or dalapon.  Trifluralin is active against bulbs"  (Weber, 2003; p. 293).

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

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

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

References:

Charles Darwin Foundation. 2008. Database inventory of introduced plant species in the rural and urban zones of Galapagos. Charles Darwin Foundation, Galapagos, Ecuador.

Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James. 1997. World weeds: natural histories and distribution. John Wiley & Sons. 1129 pp.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

McIntyre, Guy. 1991. Weeds of sugar cane in Mauritius, their description and control. Mauritius Sugar Industry Reseach Institute. 151 pp.

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.

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.