Najas guadalupensis (Spreng.) Magnus, Hydrocharitaceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Caulinia guadalupensis Sprengel

Common name(s): [more details]

English: common waternymph, Guadalupe waternymph, southern naiad, southern waternymph

French: naïade de la Guadeloupe

Habit:  aquatic herb

Description:  "Stems often profusely branched distally, 11-90 cm x 0.1-2 mm; internodes 0.1-9 cm, without prickles. Leaves spreading with age, 0.3-3.3 cm, lax in age; sheath 1-3.4 mm wide, apex rounded to truncate; blade 0.2--2.1 mm wide, margins minutely serrulate, teeth 18--100 per side, apex rounded to truncate, slightly auriculate, with 1-3 teeth, teeth unicellular; midvein without prickles abaxially. Flowers 1-3 per axil, staminate and pistillate on same plants. Staminate flowers in distal axils, 1.5-3 mm; involucral beaks 4-lobed, 0.2-1.3 mm; anther 1- or 4-loculed, 1-1.7 mm. Pistillate flowers in proximal axils, 1.5-4 mm; styles 0.3-1.5 mm; stigmas 4-lobed. Seeds not recurved, yellowish white with purple tinge, fusiform, 1.2-3.8 x 0.4-0.8 mm, apex with style situated at center; testa dull, 3 cell layers thick, pitted; aeroleareoles regularly arranged in 20-60 longitudinal rows, not ladderlike, 4-6-angled, longer than broad, end walls not raised"  (Flora of North America online).

"Plants monoecious with much-branched stems up to 6 dm long; leaves 1-2.5 cm long, 0.5-1 mm wide, generally evenly-spaced, flexible, the sheath rounded to obtuse at the junction with the blade, few-toothed, 1-celled, the apex with 1-4, short, 1-celled spines; staminate flowers 2-3 mm long, anthers 4-celled; pistillate flowers 2-3 mm long, stigmas 2-3; fruit surface dull, conspicuously reticulate, pitted"  (Herbst & Wagner, 1996; p. 11).

Habitat/ecology:  "Freshwater ponds, sluggish streams, and ditches"  (Herbst & Wagner, 1996; p. 11).

Propagation:  Seed and fragments. "The stems are brittle, and the plant is readily propagated by plant fragments"  (Imada, 2007; p. 37).

Native range:  "Native to North, Central and South America"  (Herbst & Wagner, 1996; p. 11).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Herbst, Derral R./Wagner, Warren L. (1996) (p. 11) Vouchers cited: Stemmermann & Warshauer 7189 (BISH), Stemmermann & Luce 7178 (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive cultivated	Imada, Clyde (2007) (p. 37) Vouchers cited: G. Staples 940 (BISH), C. Imada 2001-53 (BISH)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Canada Canada	Canada (country)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Costa Rica Costa Rica	Costa Rica (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)
Honduras Honduras	Honduras (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)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Oregon)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Washington)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

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)	United States (other states)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (continental except west coast) United States (other states)	USA (Florida)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

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

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

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

References:

Flora of North America Editorial Committee, eds. 2011. Flora of North America North of Mexico (online edition).

Herbst, Derral R./Wagner, Warren L. 1996. Contributions to the Flora of Hawai‘i. V. In: Evenhuis, Neal L. and Miller, Scott, E., eds. Records of the Hawaii Biological Survey for 1995. Part 2: Notes. Bishop Museum Occasional Papers. 46:8-12.

Imada, Clyde. 2007. New Hawaiian plant records for 2005-2006. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2006. Part 2: Notes. Bishop Museum Occasional Papers 96:34-41.

Staples, George W./Herbst, Derral/Imada, Clyde T. 2000. Survey of invasive or potentially invasive cultivated plants in Hawai‘i. Bishop Museum Occasional Papers No. 65. 35 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.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.