Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: iron-grass, river false buttonweed

Spanish: hierba de Santa Clara, taulmil, yerba de hierro

Habit:  herb

Description:  "Annual herbs or subshrubs to 80 cm tall, with few or many branches, leafy stems 0.5-2.5 mm thick, with 4 prominent longitudinal ridges and with scabrid hairs along the ridges; stipule sheath ca. 1 mm long, glabrous. Leaves usually opposite and subsessile, petioles 0-3 (-6) mm long; leaf blades 2-6 cm long, 2-10 (-13) mm broad, lanceolate to oblanceolate or linear-lanceolate, apex acute to acuminate, base narrowed, with minute (0.1-0.2) mm) scabridulous hairs above, glabrous beneath, 2º veins 2-3/side, usually impressed above. Inflorescences small and axillary, few-flowered, ca. 4-6 mm long, of 6-15 flowers, the flowers sessile or subsessile. Flowers with hypanthium and calyx tube 1-1.5 mm long, calyx lobes 4, 0.4-1 mm long, triangular-lanceolate to linear-lanceolate, conspicuously ciliolate along the edges; corolla white, rose, lavender, or blue, tube ca. 1.5 mm long and 1 mm diameter, lobes 0.5-1 mm long, 0.4-0.5 mm broad, ovate-oblong, obtuse at the apex, minutely puberulent distally; filaments ca. 0.3 mm long. Fruits 1.5-3 mm long, obovoid to ellipsoid or subglobose, with short ascending hispidulous hairs to 0.5 mm long, with persisting calyx lobes 0.5-1 mm long; seeds 1.1-2 mm long, 0.5-1 mm broad, ellipsoid-oblong to obovoid-ellipsoid, bluntly rounded at both ends, yellowish to dark brown, lustrous, with minute shallow pits (x40), sinus less than 1/3 the width of the seed and constricted in the middle."

"Spermacoce confusa is recognized by the very narrow scabrous leaves, small compact inflorescences, and the asymmetric unevenly setose capsule that breaks into two parts, with one failing to open" (Berger, 1993; pp. 315-316).

Habitat/ecology:  "Plants of open weedy sites, from near sea level to 1000 m elevation (to 1600 m in Guatemala" (Berger, 1993; pp. 315-316). "In open places, along trails and roadsides, in fields and along fence rows, generally distributed in tropical America as a weed" (Wiggins & Porter, 1971; pp. 439-440).

Propagation:  Seed

Native range:  Mexico through Central America and the West Indies into South America (Berger, 1993; pp. 315-316).

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) Floreana Group	Floreana Island	introduced invasive	Charles Darwin Foundation (2008)
Niue Niue	Niue Island	introduced invasive	Space, James C./Flynn, Tim (2000) (p. Voucher) Voucher: Flynn 6689 (PTBG, NIUE)
Niue Niue	Niue Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2000) (voucher ID: PTBG 30190) Taxon name on voucher: Spermacoce confusa Rendle
Niue Niue	Niue Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1997) (voucher ID: PTBG 43028) Taxon name on voucher: Spermacoce confusa Rendle

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Colombia Colombia	Colombia (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)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

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

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

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

References:

Berger, W., ed. 1993. Flora Costaricensis. Fieldiana Botany New Series, No. 33: Family #202 Rubiaceae.

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

Charles Darwin Research Station. 2005. CDRS Herbarium records.

National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.). 2000. Voucher specimen #PTBG30190(Tim Flynn 6689).

Space, James C./Flynn, Tim. 2000. Report to the Government of Niue on invasive plant species of environmental concern.  USDA Forest Service, Honolulu. 34 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.

Wiggins, I. L./Porter, D. M. 1971. Flora of the Galapágos Islands. Stanford University Press. 998 pp.