Euphorbia helioscopia (Retz.) C. E. Hubb., Euphorbiaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: ze qi

English: sun spurge, wartweed

French: euphorbe reveil matin, tithymale

Japanese: todaigusa

Spanish: lecherina, lecheruela, lechetrezna comun, mamona, pichoa, pichoga

Habit:  herb

Description:  "An annual monoecious herb with milky sap throughout; branched taproot up to 80 cm long; stems simple or branched at base, yellowish-green or sometimes purplish, glabrous, erect or ascending 15 to 60 cm tall, bearing terminal flower clusters; leaves alternate, 1 to 3 cm long, 1 to 1.5 cm wide, terminal leaves often in whorls of 5, simple, sessile, serrulate, obovate or rounded at apex, margins entire or finely toothed at apex; inflorescence composed of 5 umbel-like cyathia (cup-like receptacles, each containing a flowering group), subtended by a whorl of 5 leaves, smaller than stem leaves and not as narrow at base; each branch divides into 3 branches of second order and then 2 of third order with terminal flower cluster; involucre urn-shaped, with 4 rounded glands; flowers without petals, unisexual, flowering group with a single, central pistillate flower with a gynoecium: a long stalk with 3 styles and 3-celled ovary that extends beyond involucre after anthesis; surrounded by 10 to 12 simple staminate flowers each consisting of single stamen with small bract at base; fruit a dry, dehiscent schizocarp 4 to 5 mm in diameter with 3 carpels; at maturity carpels open violently; seed obovate to ovate in outline, circular in cross-section, 2 mm long, 1.5 mm wide, dark brown to orange-brown, with surface roughened by raised fine-meshed network; hilum kidney shaped, white and very conspicuous.  This species is recognized by its milky sap throughout, flowers in terminal umbels of branched cymes, each surrounded by a whorl of five leaves, and the sharply reticulate seed surface"  (Holm et al., 1997; p. 353).

"Annual, stems ascending, 0.5-6 dm high; leaves all obovate and very rounded or retuse at the end, finely serrate, smooth or a little hairy, those of the stem cuncate; umbel divided into usually 5 4 rays, then into 3, or at length simply forked; floral leaves narrowed to base; glands orbicular or elliptical, yellow, stalked; capsule smooth and even; seeds with coarse honeycomb-like reticulations" (Fernald, 1970; pp. 967-968).

Habitat/ecology:  Waste places and dry open soil (Fernald, 1970; pp. 967-968). In New Caledonia, "mauvaise herbe peu commune des jardins" (MacKee, 1994; p. 51).  "In Chile this species grows in the following environmental conditions:  Medium altitude up to the timber line; low altitude, interior valleys; coastal mountains, 500-2000 m; coastal areas, 0-500 m.  The plant grows in water or it has its roots within a permanent water course, this corresponds to marshes, bogs, water courses, lake and river shores; humid areas, with almost constant rainfall, short dry periods are possible (generally not longer than 1 month).  Fully exposed to the sun, level areas or slopes facing north; some shadow, some protection against direct sunlight, some shadow from vegetation, filtering about 20-40% of light"  (Chileflora).

Propagation:  Seed

Native range:  Europe, temperate and tropical Asia, northern Africa; 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
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced	Cuevas, Jaime G./Marticorena, Alicia/Cavieres, Lohengrin A. (2004) (p. 535) Voucher cited: CONC 158065, JF 186
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive cultivated	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive cultivated	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (p. 553)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Tassin, Jacques (2005)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 51) Voucher cited: MacKee 40818

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. 351)
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 351)
Chile (continental) Chile	Chile (Republic of)	introduced invasive	Holm, Leroy/Doll, Jerry/Holm, Eric/Pancho, Jaun/Herberger, James (1997) (p. 351)
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
China China	Hong Kong	introduced cultivated	Wu, Te-lin (2001) (p. 180)
Japan Japan	Japan (country)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
North Korea North Korea	North Korea (Democratic People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
South Korea South Korea	South Korea (Republic of)	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. 628) "Common in gardens, waste places and crops, occasional in riverbeds".
Taiwan Taiwan	Taiwan Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

Additional information:
Photos and other information from Chileflora.

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

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

Taxonomic information about Euphorbia helioscopia 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).

Cuevas, Jaime G./Marticorena, Alicia/Cavieres, Lohengrin A. 2004. New additions to the introduced flora of the Juan Fernández Islands: origin, distribution, life history traits, and potential of invasion. Revista Chilene de Histora Natural 77:523-538.

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.

Fernald, M. L. 1950. Gray's manual of botany, eighth edition. American Book Co. p. 588.

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.

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia. 124 pp.

Tassin, Jacques. 2005. Jacques Tassin (IAC-CIRAD), personal communication.

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.

Wu, Te-lin. 2001. Check List of Hong Kong Plants. Hong Kong Herbarium and the South China Institute of Botany. Agriculture, Fisheries and Conservation Department Bulletin 1 (revised). 384 pp.

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