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Hydrilla verticillata - (L.f.)Royle.

Common Name Hydrilla, Waterthyme
Family Hydrocharitaceae
USDA hardiness 4-8
Known Hazards None known
Habitats Grows in a variety of aquatic habitats, from acidic to basic, oligotrophic to eutrophic, fresh to brackish, and from a few centimeters deep to a meter or more if light penetrates that deeply[270].
Range A cosmopolitan plant, it is hard to know the areas where it is truly native[270]..
Edibility Rating    (0 of 5)
Other Uses    (0 of 5)
Weed Potential Yes
Medicinal Rating    (2 of 5)
Fully Hardy Water Plants Full sun
Hydrilla verticillata Hydrilla, Waterthyme

Hydrilla verticillata Hydrilla, Waterthyme


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Physical Characteristics

Hydrilla verticillata is a ANNUAL/PERENNIAL at a fast rate.
It is hardy to zone (UK) 5. It is in flower from May to October, and the seeds ripen from June to October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Water.
Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: neutral and basic (alkaline) soils and can grow in very alkaline soils.
It cannot grow in the shade. It can grow in water.

UK Hardiness Map US Hardiness Map




Edible Uses

None known

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Detergent  Miscellany

Used in the treatment of abscesses, boils and wounds, especially if there is debris in the wound[147]. A dried powder of the plant is applied to cuts and wounds to help accelerate healing[272].

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Other Uses


The plant is used in sugar refinery[177]. No more details are given.

Special Uses

Cultivation details

A submerged water plant, it prefers growing in alkaline water[200]. A good oxygenator for ponds, the plant forms a large mass with stems up to 2 metres long[1, 200]. This is a very vigorous species which can regrow from even small sections of the plant. Stem fragments become rooted by fine, unbranched adventitious roots and soon produce vegetative reproductive structures from both subterranean and erect stems[270]. Tubers produced on subterranean stems are pale brown; those produced on erect stems are dark olive-green and covered with short, stiff scales. Both types germinate quickly to produce new stems[270]. This species has often invaded native habitats, clogging waterways and crowding out native species of flora and fauna[274]. It is considered a noxious weed in many areas[274]. Plants can be monoecious or dioecious. Dioecious plants (usually female) are triploid forms whilst monoecious plants are diploid[274]. Male flowers are released from the plant under water. They float to the surface where they release their pollen to fertilize female flowers[274].

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Seed - it is quite likely that seed must be kept moist in order to maintain viability. If seed can be obtained, it is probably best sown immediately in a greenhouse in soil covered with water. Tubers - plant immediately in soil covered in water, Division - even small sections of stem will soon start producing roots when placed in water.

Other Names

If available other names are mentioned here

Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.


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Botanical References


Links / References

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Readers comment

Phoebe Wilson   Wed Jun 21 18:49:04 2000

I recently came upon your 'Plants for a Future' website at:

where there is erroneous information about Hydrilla verticillata. If you really believe the following information apparently supplied by 'Plants for a Future', made on that website:

Known Hazards: None known

then someone needs to do some more research before they provide information to other people. Just visit: to see the problems associated with Hydrilla verticillata.

Since you live in the UK, you probably have no way of knowing about these problems, but I assure you they are very real. That plant is considered an extreme pest, to the point where they are considering some kind of biocontrol. Here in Florida, we certainly would never encourage cultivation of such a plant.

I just thought you might like to update your information.

sangeeta dhote   Thu Aug 23 2007

Hydrilla verticillata can be used for water purification as it removes pollutants from water and waste water.

Debra Pipkins   Sun Feb 3 2008

can this plant affect creatinine levels in the kidney?

deepank arya   Wed Feb 13 2008

it is very beautiful for how those how like is most use in study

   Mon Apr 13 2009


Dr Manisha Acharya   Tue Jan 12 2010

I need Hydrilla verticillata powder,please advise who can supply.

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