Justicia procumbens Linnaeus, Acanthaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: jue chuang

English: waterwillow

Habit:  herb

Description:  "Decumbent perennial herb up to 40 cm in height.  Stems pubescent, rooting at the lower nodes.  Leaves opposite, simple, elliptic to ovate, 1-4 x 0.6-1.5 cm, acute at the apex and base, surfaces glabrous to sparsely pubescent; margins ciliate; petiole 1-4 mm long.  Inflorescence of 1-3 dense, ovoid to cylindrical, axillary or terminal racemes 0.6-6 cm long.  Calyx 3-6 mm long, deeply divided into 5 linear lobes with hairy margins. subsessile, subtended by two bracts similar to the calyx lobes.  Corolla bilabiate, 4-7 mm long, shallowly divided into 2 lobes on the small upper lip and 3 on the lower, larger, suborbicular lip, lavender with white markings.  Stamens 2, epipetalous, included.  Ovary superior, 2-celled.  Fruit an ovoid capsule 4-5 mm long, splitting and spreading open by 2 valves, 4-seeded"  (Whistler, 1995; p. 19).

Habitat/ecology:  "Common in disturbed places"  (Whistler, 1995; p. 19).

Propagation:  Seed

Native range:  Tropical America (Whistler, 1995; p. 19).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
American Samoa Manu‘a Islands	Ofu Island	introduced	Ragone, Diane/Lorence, David H. (2003) (p. 51)
American Samoa Manu‘a Islands	Ofu Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2001) (voucher ID: PTBG 34767) Taxon name on voucher: Justicia procumbens L.
American Samoa Manu‘a Islands	Ta‘u Island	introduced	Ragone, Diane/Lorence, David H. (2003) (p. 51)
American Samoa Manu‘a Islands	Ta‘u Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2001) (voucher ID: PTBG 34740) Taxon name on voucher: Justicia procumbens L.
American Samoa Manu‘a Islands	Ta‘u Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1990) (voucher ID: PTBG 9116) Taxon name on voucher: Justicia procumbens
American Samoa Manu‘a Islands	Ta‘u Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2002) (voucher ID: PTBG 40474) Taxon name on voucher: Justicia procumbens
American Samoa Tutuila Islands	Tutuila Island		Whistler, W. A. (1988) (p. 5) Voucher cited: McKee 2950
American Samoa Tutuila Islands	Tutuila Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1999) (voucher ID: PTBG 289) Taxon name on voucher: Justicia procumbens
American Samoa Tutuila Islands	Tutuila Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1993) (voucher ID: PTBG 27464) Taxon name on voucher: Justicia procumbens
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Philippines Philippine Islands	Philippine Islands		Merrill, Elmer D. (1923) (p. 490) In open places at low and medium altitudes.
Samoa Western Samoa Islands	Savai‘i Island		Whistler, W. A. (1988) (p. 5) Voucher cited: Whistler 1235
Samoa Western Samoa Islands	Upolu Island		Whistler, W. A. (1988) (p. 5) Voucher cited: Parham 9011
Samoa Western Samoa Islands	Upolu Island	introduced invasive	Space, James C./Flynn, Tim (2002) (p. Field notes.) Voucher: Flynn 6919 (PTBG, US, SAMOA)
Samoa Western Samoa Islands	Upolu Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (year unknown) (voucher ID: PTBG 312) Taxon name on voucher: Justicia procumbens

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
China China	China (People's Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
China China	Hong Kong	native	Wu, Te-lin (2001) (p. 253) In wasteland and open field.
Indonesia Indonesia	Indonesia (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 202)
Japan Japan	Japan (country)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Japan Ryukyu Islands	Ryukyu Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Singapore Singapore	Singapore (Republic of)	uncertain if introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 52) Weed of uncertain origin
Taiwan Taiwan	Taiwan Island	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Maldives Maldive Islands	Malè Atoll		Fosberg, F. R. (1957) (p. 34)

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

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

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

References:

Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species. Raffles Museum of Biodiversity Research, National University of Singapore. 273 pp.

Fosberg, F. R. 1957. The Maldive Islands, Indian Ocean. Atoll Research Bulletin No. 58. Pacific Science Board, National Academy of Sciences, Washington. 37 pp.

Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. 1979. A geographical atlas of world weeds. John Wiley & Sons, New York. 391 pp.

Merrill, Elmer D. 1923. An enumeration of Philippine flowering plants, vol. 3 [reprint]. Bureau of Printing, Manila. 628 pp.

National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.). 0. Voucher specimen #PTBG312(Tim Flynn; collector's voucher number unknown).

National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.). 1999. Voucher specimen #PTBG289(Tim Flynn 6570).

National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.). 2001. Voucher specimen #PTBG34740(David H. Lorence 8542).

National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.). 2001. Voucher specimen #PTBG34767(David H. Lorence 8775).

Ragone, Diane/Lorence, David H. 2003. Botanical and ethnobotanical inventories of the National Park of American Samoa. National Tropical Botanical Garden, Kalaheo, Hawaii and Pacific Cooperative Studies Unit, Department of Botany, University of Hawaii. 91 pp.

Space, James C./Flynn, Tim. 2002. Report to the Government of Samoa on invasive plant species of environmental concern. USDA Forest Service, Honolulu. 83 pp.

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Whistler, W. A. 1988. Checklist of the weed flora of western Polynesia. Technical Paper No. 194, South Pacific Commission, Noumea, New Caledonia. 69 pp.

Whistler, W. A. 1995. Wayside Plants of the Islands. Isle Botanica, Honolulu. 202 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).