Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Ceratophyllum muricatum Cham. subsp. australe (Griseb.) Les

Common name(s): [more details]

English: prickly hornwort

Habit:  aquatic herb

Description: 

"Ceratophyllum demersum L.:  "Submerged herb, richly branched, to 2 m long or sometimes longer; main stems terete, 1-3 mm diameter, smooth.  Leaves dark to bright green, rather coarse, 3-12 per node, 8-15 (-20) mm long, each leaf mostly divided twice forming four ± linear leaflets, these 4-12 (-15) mm long, serrulate, apically and dorsally provided with solitary, minute hairs.  Staminate and pistillate flowers mixed in the axils of each leaf whorl; staminate flowers with 6-12 pale green tepals and 10-12 stamens.  Fruits fleshy, brownish or dark green, the body smooth or somewhat tuberculate, broadly ellipsoid, 3.5-6 x 2-4 mm, with one apical (persistent style) and two basal spines 0.1-14 mm long."

"Ceratophyllum muricatum Cham. subsp. australe (Griseb.) Les (=Ceratophyllum llerenae Fassett): Similar to C. demersum but leaves yellowish green, dichotomously divided two to four times, segments usually inflated at base, fruits with surfaces tuberculate or papillate, and fruit margins sometimes winged and spinulose"  (Ståhl, 2003; pp. 27-28).

Habitat/ecology:  Submerged aquatic (Ståhl, 2003; pp. 27-28).

Propagation:  Seed?

Native range:  Southeastern US to South America (Ståhl, 2003; pp. 27-28). Naturalized elsewhere (GRIN).

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) Santa Cruz Group	Santa Cruz Island	possibly introduced invasive	Charles Darwin Foundation (2008)

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)
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	Ståhl, Bertil (2003) (p. 28)
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)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)

Comments:  Probably not native to the Galápagos Islands, probably introduced per Charles Darwin Research Institute.

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

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

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

References:

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.

Ståhl, Bertil. 2003. Ceratophyllaceae [55B.]. Flora of Ecuador 70, pp. 27-28.

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