Alternanthera Species, Alligator Weed, Alligatorweed

Alternanthera philoxeroides

Family: Amaranthaceae
Genus: Alternanthera (al-ter-NANTH-ur-uh) (Info)
Species: philoxeroides (fil-oh-zer-OY-deez) (Info)
Synonym:Achyranthes philoxeroides
Synonym:Alternanthera philoxerina
Synonym:Telanthera philoxeroides


Ponds and Aquatics

Water Requirements:

Very high moisture needs; suitable for bogs and water gardens

Sun Exposure:

Full Sun



Foliage Color:

Unknown - Tell us


36-48 in. (90-120 cm)


36-48 in. (90-120 cm)


USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Where to Grow:

Unknown - Tell us


Unknown - Tell us

Bloom Color:

White/Near White

Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Blooms repeatedly

Other details:

May be a noxious weed or invasive

Soil pH requirements:

Unknown - Tell us

Patent Information:


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

From herbaceous stem cuttings

Seed Collecting:

N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed


This plant is said to grow outdoors in the following regions:

Deland, Florida

Port Saint Lucie, Florida

Cordele, Georgia

Gardeners' Notes:


On Nov 28, 2012, 4plantsonly from (Zone 9b) wrote:

Pulls up easy ...what you don't have to wade out in water to reach...however it is so tender breaks off just as easy leaving the rest of the plant....don't plant this ....if you see it starting , remove it ...I am sure it has some use somewhere...but I guarantee you it is not useful in your ponds...


On May 18, 2008, Cordeledawg from Cordele, GA (Zone 8a) wrote:

Horrible aquatic weed that has covered my beautiful water lilies in my pond. I am getting ready for war over this weed. Had the county agent out to help me determine how to get rid of it. He advised me to kill it with Rodeo in small patches at a time as to not deplete the oxygen in the water. I borrowed a boat and will soon start the fight. I may rake out the dying foliage, just depends if I'm physically able to do it without falling out of the boat.


On Nov 22, 2006, frostweed from Josephine, Arlington, TX (Zone 8a) wrote:

Alligator Weed, Alligatorweed Alternanthera philoxeroides ia Naturalized in Texas and other States is considered an invasive noxious plant and is prohibited in Texas.


On Apr 1, 2004, giftofthegab from sydney,
Australia wrote:

A perennial herb either free floating or a creeping terrestrial.
Leaves are narrow and elliptical, flowers are a silvery white, rounded on long stalks. Stems are hollow, which form a dense mat.
Considered a noxious weed in Australia due to easy propagation from almost any part of the plant, including rhizomes, stolons or stems.


On Jul 4, 2003, Terry from Murfreesboro, TN (Zone 7a) wrote:

Takes up residence in disturbed wetlands, and if not eradicated, can form a thick, tangled mat up to 3 feet thick.