Hygrophila costata Nees et al., Acanthaceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results:  Plant Pest Risk Assessment of Hygrophila costata from the Department of Primary Industry, Queensland, Australia.

Other Latin names:  Hygrophila brasiliensis (Spreng.) Lindau; Hygrophila guianensis Nees.; Ruellia brasiliensis Spreng.

Common name(s): [more details]

English: glush weed, gulf swampweed, hygrophila

Spanish: yerba de hicotea

Habit:  aquatic herb

Description:  "A perennial, amphibious marsh plant generally 0.5-1 m tall, but up to 2.5 m tall when scrambling up through taller vegetation. While it is generally an erect plant when grown in isolation, specimens that are growing close together often have stems that grow along the ground, with roots produced at the point where nodes touch the ground. Leaves opposite, simple, 3-18 cm long, 1-5 cm wide, oblong to elliptic-lanceolate, narrowed at base to a very short petiole. Stems softly hispid with long pluricellular hairs, rarely branched. Flowers bisexual, zygomorphic, white (or light rose), 9-11 mm wide and produced in cymes in the leaf axils. Four stamens (occasionally two fertile and two sterile); anther sac at same level. The ovary is superior, two-locular and the fruit is a two-valved capsule, 14-17 mm long. Each capsule has 12-18 seeds. Seeds are pale brown, round, flattened, smooth, 0.3-1 mm long"  (Queensland DPI risk assessment of Hygrophila costata).

Habitat/ecology:  "H. costata can grow either fully submerged or above water level on nearby moist ground. In tropical America, H. costata and its synonym, H. guianensis, are recorded to grow along muddy river banks, on silt, gravel banks and rocks in rivers.  In Queensland and New South Wales [Australia], H. costata has naturalised along the banks of creeks and in shallow, freshwater wetlands. At a few locations it has formed pure stands. At these sites, the native vegetation has been heavily disturbed and eutrophic conditions prevail. It is not known to what degree eutrophication is a requirement for survival and proliferation of this plant in Australia"  (Queensland DPI risk assessment).

Propagation:  Seed and stem fragments.  "Readily propagated from cuttings or from severed leaves.  Aquarium guides ... note that H. costata can be propagated from a 15 cm section of stem, which produces roots. Presumably, wild specimens growing in marshy areas can produce new plants downstream if floodwaters break off sections of stems or leaves.  The small seeds are sticky when wet but there is no information available on dispersal or longevity"  (Queensland DPI risk assessment of Hygrophila costata).

Native range:  Florida (PLANTS database), Mexico, Central and South America (GRIN).

Presence:

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 cultivated	Csurhes, Steve (2008) (p. 3)
Australia Australia (continental)	Queensland	introduced invasive cultivated	Csurhes, Steve (2008) (p. 3)
Central America Central America (Pacific rim)	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013) Chiapas, Guerrero, Oaxaca, Veracruz
South America (Pacific rim) South America (Pacific rim)	Colombia	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Also reported from
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
United States (continental except west coast) United States (other states)	USA (Florida)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2013)

Control:  If you know of control methods for Hygrophila costata, please let us know.