Hydrilla verticillata(L.f.) Royle

Florida-elodeaHydrillaIndian StargrassWater-thymewaterthyme

WFO wfo-0000769366 Accepted WFO 2026-06 8 photographs CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Hydrilla verticillata, photographed by Jay Pruett
fig. a Jay Pruett, CC BY 4.0 / 2022-04-05 / obs. 186644181
Hydrilla verticillata, photographed by Josiah Londerée
fig. b Josiah Londerée, CC BY 4.0 / obs. 186312862
Hydrilla verticillata, photographed by Ong Jyh Seng
fig. c Ong Jyh Seng, CC BY-SA 4.0 / obs. 173247224
Hydrilla verticillata, photographed by Ong Jyh Seng
fig. d Ong Jyh Seng, CC BY-SA 4.0 / obs. 173247707
Hydrilla verticillata, photographed by chiuluan
fig. e chiuluan, CC BY 4.0 / obs. 171851456
Hydrilla verticillata, photographed by Tom Field
fig. f Tom Field, CC BY 4.0 / obs. 169048783
Hydrilla verticillata, photographed by Tom Field
fig. g Tom Field, CC BY 4.0 / obs. 170866115
Hydrilla verticillata, photographed by Tom Field
fig. h Tom Field, CC BY 4.0 / obs. 169804142

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

The specimen a real sheet, in a real collection

Herbarium
The New York Botanical Garden
Accession
201260
Filed as
Hydrilla verticillata (L.f.) Royle
Det. by
C. R. Annable 1996-01-01
Collected
C. R. Annable 1996-01-31
Origin
US
The sheet
View the digitised specimen (CC BY 4.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Native range 63 botanical countries

Regions where Hydrilla verticillata is native: Burundi, DR Congo, Kenya, Rwanda, Tanzania, Uganda, Zambia, Afghanistan, Altay, Amur, China North-Central, China South-Central, China Southeast, Hainan, Iran, Irkutsk, Japan, Kazakhstan, Khabarovsk, Korea, Krasnoyarsk, Manchuria, Mongolia, Nansei-shoto, Primorye, Taiwan, Tibet, West Siberia, Yakutiya, Assam, Bangladesh, Borneo, Cambodia, East Himalaya, India, Jawa, Laos, Lesser Sunda Is., Malaya, Maluku, Myanmar, Nepal, New Guinea, Pakistan, Philippines, Sri Lanka, Sulawesi, Sumatera, Thailand, Vietnam, West Himalaya, New South Wales, Northern Territory, Queensland, South Australia, Victoria, Western Australia, Baltic States, Belarus, Northwest European Russia, Poland, Marianas, New Caledonia BurundiDR CongoKenyaRwandaTanzaniaUgandaZambiaAfghanistanAltayAmurChina North-CentralChina South-CentralChina SoutheastHainanIranIrkutskJapanKazakhstanKhabarovskKrasnoyarskManchuriaMongoliaPrimoryeTaiwanTibetWest SiberiaYakutiyaAssamBangladeshBorneoCambodiaEast HimalayaIndiaJawaLaosLesser Sunda Is.MalayaMalukuMyanmarNepalNew GuineaPakistanPhilippinesSri LankaSulawesiSumateraThailandVietnamWest HimalayaNew South WalesNorthern TerritoryQueenslandSouth AustraliaVictoriaWestern AustraliaBaltic StatesBelarusNorthwest European RussiaPolandNew Caledonia KoreaNansei-shotoMarianas
Native distribution of Hydrilla verticillata, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Afghanistan AFG ASIA-TEMPERATE
Altay ALT
Amur AMU
China North-Central CHN
China South-Central CHC
China Southeast CHS
Hainan CHH
Iran IRN
Irkutsk IRK
Japan JAP
Kazakhstan KAZ
Khabarovsk KHA
Korea KOR
Krasnoyarsk KRA
Manchuria CHM
Mongolia MON
Nansei-shoto NNS
Primorye PRM
Taiwan TAI
Tibet CHT
West Siberia WSB
Yakutiya YAK
Assam ASS ASIA-TROPICAL
Bangladesh BAN
Borneo BOR
Cambodia CBD
East Himalaya EHM
India IND
Jawa JAW
Laos LAO
Lesser Sunda Is. LSI
Malaya MLY
Maluku MOL
Myanmar MYA
Nepal NEP
New Guinea NWG
Pakistan PAK
Philippines PHI
Sri Lanka SRL
Sulawesi SUL
Sumatera SUM
Thailand THA
Vietnam VIE
West Himalaya WHM
Burundi BUR AFRICA
DR Congo ZAI
Kenya KEN
Rwanda RWA
Tanzania TAN
Uganda UGA
Zambia ZAM
New South Wales NSW AUSTRALASIA
Northern Territory NTA
Queensland QLD
South Australia SOA
Victoria VIC
Western Australia WAU
Baltic States BLT EUROPE
Belarus BLR
Northwest European Russia RUW
Poland POL
Marianas MRN PACIFIC
New Caledonia NWC

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Where it actually grows measured, from 1,990 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -18.9 °C 6.1 °C 22.4 °C
Warmest month, mean daily high 24.6 °C 31.0 °C 35.2 °C
Annual rainfall 540 mm 1,268 mm 2,637 mm
Rainfall in the driest quarter 35 mm 198 mm 314 mm

It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,990 research-grade observations of Hydrilla verticillata that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.

Also published as 27 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Elodea verticillata (L.f.) F.Muell.
  • Epigynanthus blumei Hassk.
  • Hydora lithuanica (Besser ex Rchb.) Besser
  • Hydrilla angustifolia Hassk.
  • Hydrilla dentata Casp.
  • Hydrilla dentata var. pomeranica (Rchb.) Casp.
  • Hydrilla lithuanica (Rchb.) Dandy
  • Hydrilla najadifolia Zoll. & Moritzi
  • Hydrilla ovalifolia Rich.
  • Hydrilla polysperma Blatt.
  • Hydrilla roxburghii Steud.
  • Hydrilla subulata Royle
  • Hydrilla verticillata var. brevifolia Casp.
  • Hydrilla verticillata var. crispa Casp.
  • Hydrilla verticillata var. inconsistens Casp.
  • Hydrilla verticillata var. roxburghii Casp.
  • Hydrilla verticillata var. tenuis Casp.
  • Hydrilla wightii Planch.
  • Hydrospondylus submersus Hassk.
  • Ixia aquatica Muhl. ex Spreng.
  • Serpicula verticillata L.f.
  • Udora lithuanica Andrz. ex Besser
  • Udora lithuanica Rchb.
  • Udora occidentalis W.D.J.Koch

and 3 more.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.