Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Habit:  vine

Description: 

var. hirta: "A twining or prostrate herb; the prostrate specimens rooting at the nodes or sometimes at the internodes.  Stems slender, 20-50 cm long, fililform, sparsely patently hirsute or glabrous.  Leaves very variable in form, linear, linear-oblong, oblong-lanceolate, oblong to ovate-oblong or ovate, occasionally orbicular to subquadrate; the narrow leaves 3-6 by 1/3-1 cm, 5-12 times as long as broad, the broad ones 1 "-4 " by 4/5-2 " cm, 1-5 times as long as broad, rounded, truncate, more or less cordate or hastate at the base with small or large, obtuse, spreading or parallel basal lobes, obtuse to slightly emarginate and mucronulate at the apex, the surfaces glabrous or sparsely hairy beneath and along the margins, sometimes also above, rarely the indumentum is more developed, especially on stems, petioles, leafblades and basal part of peduncles; petiole short, (1-) 3-8 (-20) mm.  Peduncles filiform, variable in length, 1-7 " cm, glabrous or with a few hairs near the base.  Flowers 1 to few, mostly up to 4, in some specimens to 8; the ramifications of peduncle monochasial (racemelike and unilateral), or the first ramification dichasial and the subsequent ones monochasial.  Pedicels 3-5 mm, glabrous.  Bracts ovate, obtuse, 1-2 mm long, glabrous, persistent.  Flower-buds oblong to elliptic, obtuse.  Sepals glabrous, unequal, the 2 outer ones shorter, elliptic, obtuse, 3-4 mm long, the 3 inner oblong or elliptic-oblong, obtuse, 4 "-6 mm long; sepals slightly enlarged in fruit, to 6-7 mm, with more or less prominent nerves.  Corolla broadly funnel-shaped, 1 "-2 cm long, pale-yellow or whitish, glabrous, midpetaline bands in dried state with distinct dark nerves.  Filaments hairy at the base; anthers spirally twisted.  Ovary glabrous, 2-celled. Capsule broadly ovoid to globular, with a tink papery wall, smooth, glabrous, crowned by the base of the style, ca 6 mm long, 1-celled, 4-valved. Seeds 4 or less, dark brown or black, glabrous or sparsely floccose at the margins and the hilum."  (van Steenis, 1954)

var. retusa:  "Differs from var. hirta by having the inner sepals broader, broadly elliptic to subquadrate, with a truncate to retuse, mucronulate apex, and the outer ones elliptic, obtuse to acutish, mucronulate.  Leaves oblong, 4/5-2 " cm long, hastate at the base, with entire or 1-2-dentate lobes, obtuse to subretuse and mucronulate at the apex.  Peduncles short, to 1 cm long, 1- or sometimes 2-3-flowered" (van Steenis, 1954; pp. 442-443).

Habitat/ecology:  "In open grasslands, along waysides, in dry rice-fields, from sea level to 1100 m" (van Steenis, 1954; pp. 442-443).

Propagation:  Seed

Native range:  var. hirta: India to southern China, Thailand and tropical Australia, throughout Malaysia.
var. retusa: Philippines (Luzon). (van Steenis, 1954; pp. 442-443).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Solomon Islands Solomon Islands	Solomon Islands		Swarbrick, John T. (1997) (p. 94)
Solomon Islands Solomon Islands	Solomon Islands	native	Hancock, I. R./Henderson, C. P. (1988) (p. 91)

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)	Queensland	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Cambodia Cambodia	Cambodia (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Indonesia Indonesia	Indonesia (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Taiwan Taiwan	Taiwan Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)

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

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

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

References:

Hancock, I. R./Henderson, C. P. 1988. Flora of the Solomon Islands. Research Bulletin No. 7. Ministry of Agriculture and Lands, Honiara. 203 pp.

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

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