Fanwort - Cabomba caroliniana
State Rank Reason (see State Rank above)
Cabomba caroliniana is not known to occur in Montana. A conservation status rank is not applicable (SNA) because the plant is not a suitable target for conservation activities. The purpose of this profile is to provide awareness and education to prevent its introduction into Montana.
Cabomba caroliniana is cultivated for aquariums, but when released into the natural environment it can become an aggressive weed. Please do not release any type of aquarium plant into waterways because the consequences of invasion are far too great. Preventing deliberate plantings and spread from plant fragments are the best means to keep this plant out of Montana’s waters.
PLANTS: An aquatic perennial plant with floating and submersed leaves and flowers occurring on or above the water. Mucilage is absent. Sources: Gilbin et al. [eds.] 2018; Richard in FNA 1997.
LEAVES: Floating leaves are linear-elliptic, 1-3.5 cm wide, and entire or notched. The petiole (leaf stem) is up to 4 cm long and connects to the underside of the leaf’s center. Submersed leaves are palmately dissected into filiform to linear segments. Both leaf types are oppositely arranged. Sources: Gilbin et al. [eds.] 2018; Richard in FNA 1997.
INFLORESCENCE: White to yellowish flowers are solitary, occurring on or above the water, and have long peduncles (flower stem).
Flowering late spring to early fall (Richard in FNA 1997). Flowering occurs later with decreasing latitude (Richard in FNA 1997).
Known to occur in Kansas where it is likely extirpated (Richard in FNA 1997).
Introduced into the US states of the New England, southeast, and Pacific Northwest regions (Richard in FNA 1997). It was first documented in Oregon in 1962 where it was noted as becoming abundant in several sloughs (Imdorf et al. 1994). It was first documented in Washington in 1992. It occurs west of the Cascades from southwest Washington to California (Gilbin et al. [eds.] 2018).
For maps and other distributional information on non-native species see:
Nonindigenous Aquatic Species Database from the U.S. Geological Survey
Invasive Species Habitat Tool (INHABIT) from the U.S. Geological Survey
Invasive Species Compendium from the Centre for Agriculture and Bioscience International (CABI)
EDDMapS Species Information EDDMapS Species Information
Acidic to alkaline shallow ponds, lakes, pools in marshes, sluggish streams, ditches, and reservoirs (Gilbin et al. [eds.] 2018; Richard in FNA 1997).
FLOWER and FRUIT [Adapted from Gilbin et al. [eds.] 2018; Richard in FNA 1997]
Small flowers with male and female parts. Sepals (5-12 mm long) and petals (4-12 mm long) are present, separate, and similar in color (white to yellowish). In the southeast some plants are purplish tinged which could be produced by environmental conditions. Petals have yellow nectaries at their base, but sepals do not. Sepals and petasl are broadly obtuse at their tips and sometimes are notched. The 3-6 yellow, stamens are arranged opposite of the petals and are shorter. The 2-4 pistils each have (1-)3(-5) ovules and a style about the length of the ovary.
Fruit is an achene- or follicle-like and persistent. Fruit is pear-shaped, 4-7 mm long.
Fanwort is cultivated for aquariums, but when released into natural areas it can become an aggressive weed. Please do not release any type of aquarium plant into waterways because the consequences of invasion are far too great. Preventing deliberate plantings and spread from plant fragments are the best means to keep this plant out of Montana’s waters. Contact information for Aquatic Invasive Species personnel:Montana Fish, Wildlife, and Parks Aquatic Invasive Species staff.Montana Department of Natural Resources and Conservation's Aquatic Invasive Species Grant Program.Montana Invasive Species Council (MISC).Upper Columbia Conservation Commission (UC3).
Threats or Limiting Factors
Fanwort is commonly cultivated for use in aquariums (Imdorf et al. 1994). In the Pacific Northwest it has escaped developing populations that are dense, robust, and reproducing vegetatively. In the eastern and southeastern states, it is an aggressive weed (Richard in FNA 1997).
- Literature Cited AboveLegend: View Online Publication
- eFloras. No Date. Published on the Internet http://www.efloras.org. Missouri Botanical Garden Herbarium, St. Louis, Missouri and Harvard University Herbarium, Cambridge, Massachusetts
- Imdorf, Gregory J., Donald J. Pinkava, Shelley McMahon, Mark Fishbein, John A. Christy, Mark D. Sytsma, and Michael C. Vasey. 1994. Noteworthy Collections. Madrono, Volume 41, Number 4, pp. 330-333.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- Flora of North America Editorial Committee. 1997. Flora of North America North of Mexico. Volume 3. Magnoliophyta: Magnoliidae and Hamamelidae. Oxford University Press, Inc., New York, NY. xxiii + 590 pp.
- Giblin, David E., Ben S. Legler, Peter F. Zika, and Richard G. Olmstead (editors). 2018. Flora of the Pacific Northwest: An Illustrated Manual. Second Edition. University of Washington Press in Association with Burke Museum of Natural History and Culture, Seattle, Washington. 882 pp.