Hydrilla verticillata

Distribution Map: Based on vouchered plant specimens from wild populations. Cultivated occurrences are not mapped. View county names by placing the cursor over the map.

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Family:	HYDROCHARITACEAE
Species:	Hydrilla verticillata (L.f.)Royle
Common Name:	WATERTHYME; HYDRILLA
Plant Notes:	The species has been divided into five subspecies, with subsp. verticillata being found in Florida (Tippery 2023).
Status:	Not Native, FISC(I), OBL (NWPL)
Specimen:	View details of USF Herbarium specimens

** Not applicable or data not available.

Classification

Division
Class
Sub Class
Order	ALISMATALES
Family	HYDROCHARITACEAE
Genus	Hydrilla
Species	Hydrilla verticillata (L.f.)Royle - WATERTHYME; HYDRILLA

Citation

Citation	HYDRILLA VERTICILLATA (Linnaeus f.) Royle, Ill. Bot. Himal. Mts. 1: 376. 1839.
Basionym:	Serpicula verticillata Linnaeus f. 1782.
Type:	INDIA: Without data (holotype: LINN 1106.1).

** Not applicable or data not available.

Source

County	Herbaria	Literature Citation (If Applicable)
Alachua	FLAS
Brevard	USF
Broward	USF
Citrus	FLAS
Collier	FTG
DeSoto	USF
Duval	FLAS	Lit-GA: Zomlefer et al., J. Bot. Res. Inst. Texas 1: 1171. 2007.
Escambia	USF
Franklin	FSU
Gilchrist	FLAS
Hardee	USF
Hendry	FTG
Hernando	USF
Hillsborough	USF
Holmes	USF
Indian River	USF
Jefferson	USF
Leon	USF
Levy	USF
Manatee	USF
Martin	FTG
Miami-Dade	FTG
Okaloosa	USF
Okeechobee	USF
Orange	USF
Osceola	USF
Palm Beach	FLAS
Pasco	USF
Pinellas	USF
Polk	FSU
Putnam	FLAS
Santa Rosa	USF
Sarasota	USF
Seminole	FSU
Volusia	USF
Wakulla	FSU

Synonyms

– Denotes synonyms that are applicable to the state. Show these synonyms only

Synonym	Full Citation	Basionym	Type
Elodea verticillata	Elodea verticillata (Linnaeus f.) F. Mueller, Key Vict. Pl. 1: 423. 1888.	BASIONYM: Serpicula verticillata Linnaeus f. 1782.
Hydrilla ovalifolia	Hydrilla ovalifolia Richard, Mém. Cl. Sci. Math. Nat. Hist. Inst. France 12(2): 9, 76. 1814, nom. illegit.	BASIONYM: Serpicula verticillata Linnaeus f. 1782.
Serpicula verticillata	Serpicula verticillata Linnaeus f., Suppl. Pl. 416. 1782 ("1781").		TYPE: INDIA: Without data (holotype: LINN 1106.1).
Udora verticillata	Udora verticillata (Linnaeus f.) Sprengel, Syst. Veg. 1: 170. 1824 ("1825").	BASIONYM: Serpicula verticillata Linnaeus f. 1782.
Anacharis pomeranica	Anacharis pomeranica (Reichenbach) Petermann, Deutschl. Fl. 530. 1849.	BASIONYM: Udora pomeranica Reichenbach 1845.
Hottonia serrata	Hottonia serrata Willdenow, Sp. Pl. 1: 814. 1798.		TYPE: INDIA:
Hydora lithuanica	Hydora lithuanica (Besser ex Reichenbach) Andrzejowski ex Besser, Flora 15(2, Beibl.): 13. 1832.	BASIONYM: Udora lithuanica Besser ex Reichenbach 1831.
Hydrilla dentata var. pomeranica	Hydrilla dentata Caspary, var. pomeranica (Reichenbach) Caspary, Bot. Zeitung (Berlin) 11: 805. 1853.	BASIONYM: Udora pomeranica Reichenbach 1845.
Hydrilla lithuanica	Hydrilla lithuanica (Besser ex Reichenbach) Dandy, in Clapham et al., Fl. Brit. Isles 1183. 1952.	BASIONYM: Udora lithuanica Besser ex Reichenbach 1831.
Hydrilla najadifolia	Hydrilla najadifolia Zollinger & Moritzi ex Moritzi, Syst. Verz. 91. 1846.		TYPE: INDONESIA: Java: Tjikoya, 29 May 1842, Zollinger 125 (holotype: P; isotypes: BM, G, L).
Hydrilla polysperma	Hydrilla polysperma Blatter, J. Proc. Asiat. Soc. Bengal, ser. 2. 26: 356. 1931.		TYPE: INDIA: Rajasthan: Mount Abu, Naki talao, Oct 1916, Hallberg & Blatter 11189 (holotype: BLAT?).
Hydrilla wightii	Hydrilla wightii Planchon, Ann. Sci. Nat., Bot., ser. 3. 2: 79. 1849.		TYPE: INDIA: "in peninsula Indiae or.", s.d., Wight s.n. (holotype: K; isotype: BM).
Hydrospondylus submersus	Hydrospondylus submersus Hasskarl, Flora 25(2, Beibl.): 33. 1842.		TYPE: INDONESIA: Java: "prope & intra hortorum Tjipannas" (holotype: L?).
Udora lithuanica	Udora lithuanica Besser ex Reichenbach, Fl. Germ. Excurs. 139. 1831.		TYPE: U.S.S.R.: Litva (S.S.R.): Vilnius, Lake Szuriuta (Szwinta), s.d. Besser s.n. (holotype: W; isotypes: BM, L, P).
Udora pomeranica	Udora pomeranica Reichenbach, Icon. Fl. Germ. Helv. 7: 31, t. 59(104). 1845.		TYPE: POLAND: Szczecin (Stettin), Dammscher See, 1844, Reichenbach s.n. (holotype: W?; isotypes: G, P).

Specimens

Country	State	County	Date	Specimen	Notes
USA	Florida	Pinellas Co.	21 Nov 1973	S. A. Putnam s.n.
USA	Florida	Sarasota Co.	23 Apr 1971	L. E. Peaden s.n.
USA	Florida	Broward Co.	18 Oct 1985	B. F. Hansen 10526
USA	Florida	Pinellas Co.	09 Nov 1973	S. A. Putnam s.n.
USA	Florida	Pinellas Co.	30 Oct 1978	E. Stere 55
USA	Florida	Hillsborough Co.	23 Nov 1968	O. K. Lakela 31757
USA	Florida	Pinellas Co.	25 Sep 1976	P. Genelle 2411
USA	Florida	Pinellas Co.	21 Apr 1984	G. Fleming 3688
USA	Florida	Orange Co.	07 May 1992	J. Cutler s.n.
USA	Florida	Volusia Co.	08 May 2006	J. M. Kunzer 1648
USA	Florida	Broward Co.	21 Feb 1970	W. L. McCart 11313
USA	Florida	Broward Co.	07 Dec 1969	W. L. McCart 11245
USA	Florida	Hillsborough Co.	03 May 1974	A.G. Shuey s.n.
USA	Florida	Leon Co.	19 Sep 1982	R. R. Haynes 8670
USA	Florida	Hernando Co.	10 Jun 2006	J. M. Kunzer 1825
USA	Florida	Hillsborough Co.	18 Nov 1977	A. N. Arcuri 639
USA	Florida	Broward Co.	22 Apr 1998	P. L. Howell 213
USA	Florida	Orange Co.	01 Aug 2001	S. Myers 242
USA	Florida	Lake Co.	25 Oct 1986	R. F. Daubenmire s.n.
USA	Florida	Hillsborough Co.	24 Aug 1978	C. G. Wright 89
USA	Florida	Brevard Co.	01 Sep 2004	T. MacClendon 297
USA	Florida	Leon Co.	17 Jul 1986	B. F. Hansen 11058
USA	Florida	Broward Co.	28 Feb 1970	W. L. McCart 11357
USA	Florida	Manatee Co.	06 Jun 1984	G. Robinson 631
USA	Florida	Pinellas Co.	10 Oct 1971	P. Genelle 1043
USA	Florida	Hillsborough Co.	16 Jun 1977	A. N. Arcuri 267
USA	Florida	Okeechobee Co.	25 Sep 1986	B. F. Hansen 11270
USA	Florida	DeSoto Co.	28 Aug 2008	A. R. Franck 827
USA	Florida	Pasco Co.	10 Jun 2004	C. vanHoek WB0465
USA	Florida	Indian River Co.	08 May 2011	S. Myers 519
USA	Florida	Jefferson Co.	10 Aug 2011	S. Myers 531
USA	Florida	Levy Co.	27 Aug 2011	S. Myers 534
USA	Florida	Osceola Co.	15 Sep 2012	S. Myers 698
USA	Florida	Okaloosa Co.	26 Sep 2013	F. Butera s.n.
USA	Florida	Pinellas Co.	21 Apr 1998	C. B. Cochrane s.n.
USA	Florida	Hardee Co.	09 May 2014	A. R. Franck 3318
USA	Florida	Osceola Co.	23 Jun 2014	S. Myers 1325
USA	Georgia	Seminole Co.	05 Sep 1979	S. B. Jones 23657	Causes serious problems with recreation on Lake Seminole.
USA	South Carolina	Berkeley Co.	06 Jul 1984	S. Kozlowski s.n.
USA	North Carolina	Wake Co.	24 Aug 1986	C. A. Aulbach-Smith 4183
USA	South Carolina	Clarendon Co.	23 Sep 1983	C. A. Aulbach-Smith 2820
USA	Louisiana	Terrebonne Par.	24 May 1978	G. N. Montz 4564
USA	Alabama	Choctaw Co.	02 Dec 1978	R. R. Haynes 7000
USA	Georgia	Jones Co.	28 Nov 2015	A. R. Franck 3982
Dominica		St. Paul Par.	10 Mar 1993	S. R. Hill 24712
USA	Florida	Santa Rosa Co.	19 May 2014	R. Abad s.n.
USA	Florida	Miami-Dade Co.	10 Feb 1973	R. E. Mossman 1177(8)
USA	Florida	Holmes Co.	09 Sep 2015	F. Butera s.n.
USA	Florida	Escambia Co.	04 Jun 2015	F. Butera s.n.
Panama	Canal Zone Prov.		23 Mar 1968	M. D. Correa A. 858
Panama	Canal Zone Prov.		26 May 1969	R. L. Lazor 3493
Venezuela	Aragua		12 Mar 1980	R. R. Haynes 7646
USA	Florida	Hillsborough Co.	30 Oct 2012	S. Dickman 609

Listed Status: Florida

Listed Status:	(Florida):Source - Plants in the Preservation of Native Flora of Florida Act. Chapter 5B-40, Florida Administrative Code. 1998, amended.
Endangered:	A species of plants native to the state that are in imminent danger of extinction within the state, the survival of which is unlikely if the causes of a decline in the number of plants continue, and includes all species determined to be endangered or threatened pursuant to the Federal Endangered Species Act of 1973, as amended.
Threatened:	Listed as Threatened Plants in the Preservation of Native Flora of Florida Act. Defined as species of plants native to the state that are in rapid decline in the number of plants within the state, but which have not so decreased in such number as to cause them to be endangered.

Listed Status: US

Listed Status: US	(U.S.) Source - List of Endangered and Threatened Wildlife and Plants under the provisions of the Endangered Species Act of 1973, as amended.
Endangered:	Any species which is in danger of extinction throughout all or a significant portion of its range.
Threatened:	Any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.

WAP: Wetland AssessmentProcedure

Wetland Assessment Procedure (WAP): Source - Southwest Florida Water Management District, Wetland Assessment Procedure Instruction Manual for Isolated Wetlands (March 2005).

AD:	Adaptive Species. Plant species designated as FAC or Upland by DEP, but commonly seen in the transition zone in limited numbers.
D:	Deep Species. Plant species commonly found in the deep zone, and designated either FAC or OBL by DEP.
OD:	Outer Deep Species. Plant species commonly found in the outer deep zone, and designated either FACW or OBL by DEP.
T:	Transition Species. Plant species commonly found in the transition zone, and designated either FACW or OBL by DEP.
U:	Upland Species. Plant species that are not expected to be seen in wetlands.

ANY - WAP critieria is not taken into consideration
Yes - Show results with WAP designations
No - Show results without WAP designations

FISC: Florida Invasive Species Council

FISC:

Source - Florida Invasive Species Council's 2017 List of Florida's Most Invasive Species

Category I - Species that are invading and disrupting native plant communities in Florida. This definition does not rely on the economic severity or geographic range of the problem, but on the documented ecological damage caused.

Category II - Species that have shown a potential to disrupt native plant communities. These species may become ranked as Category I, but have not yet demonstrated disruption of natural Florida communities.

DEP: Department of Environmental Protection

Wetland Status, Department of Environmental Regulation (DEP): Source - Delineation of the Landward Extent of Wetlands and Surface Waters, Chapter 62-340, Florida Administrative Code. 1994.

OBL:	Obligate wetland. Occurs almost always under natural conditions in wetlands.
FACW:	Facultative Wetland. Usually occurs in wetlands, but occasionally found in non-wetlands
FAC:	Facultative. equally likely to occur in wetlands or non-wetlands.

NWPL: National Wetland Plant List

National Wetland Plant List (NWPL): Source - Lichvar, R.W., M. Butterwick, N.C. Melvin, and W.N. Kirchner. 2014. The National Wetland Plant List: 2014 Update of Wetland Ratings. Phytoneuron 2014-41: 1-42.

OBL:	Obligate Wetland. Occurs almost always (estimated probability 99%) under natural conditions in wetlands.
FACW:	Facultative Wetland. Usually occurs in wetlands (estimated probability 67%-99%), but occasionally found in non-wetlands.
FAC:	Facultative. Equally likely to occur in wetlands or non-wetlands (estimated probability 34%-66%).
FACU:	Facultative Upland. Usually occurs in non-wetlands (estimated probability 67%-99%), but occasionally found in wetlands (estimated probability 1%-33%).
UPL:	Obligate Upland. Occurs in wetlands in another region, but occurs almost always (estimated probability 99%) under natural conditions in non-wetlands in the regions specified.

Persisting

Identifying species that appear as waifs or only periodically appear in the flora for a few seasons.

Any - Persisting critieria is not taken into consideration
Yes - Show results with a Persisting value of Y
No - Show results without Persisting value of N

Duration

Annual:	Plants that perform their entire lifecycle within a single growing season. All roots, stems, and leaves die at the end of the growing season. Over wintering seeds allow the next generation to appear.
Biennial:	A plant that is typically vegetative its first year and blooms the following season. Once it has bloomed and set seed, the plant dies. Garlic mustard is an example of a biennial.
Perennial:	These plants live for three or more seasons. Many perennials may not be mature enough to bloom during its first year. Perennial wildflowers re-grow each season from overwinter root material.

Category

Vascular:	Any of various plants that have the vascular tissues xylem and phloem. The vascular plants include all seed-bearing plants (the gymnosperms and angiosperms) and the pteridophytes (including the ferns, lycophytes, and horsetails). Also called tracheophyte.
Bryophyte:	A large group of seedless green plants including the mosses, liverworts, and hornworts. Bryophytes lack the specialized tissues xylem and phloem that circulate water and dissolved nutrients in the vascular plants. Bryophytes generally live on land but are mostly found in moist environments, for they have free-swimming sperm that require water for transport. In contrast to the vascular plants, the gametophyte (haploid) generation of bryophytes constitutes the larger plant form, while the small sporophyte (diploid) generation grows on or within the gametophyte and depends upon it for nutrition.
Lichen:	The mutualistic symbiotic association of a fungus with an alga or a cyanobacterium, or both. The fungal component of a lichen absorbs water and nutrients from the surroundings and provides a suitable environment for the alga or cyanobacterium. These live protected among the dense fungal hyphae and produce carbohydrates for the fungus by photosynthesis. Owing to this partnership, lichens can thrive in harsh environments such as mountaintops and polar regions. The more familiar lichens grow slowly as crusty patches, but lichens are found in a variety of forms, such as the tall, plantlike reindeer moss. The association between the different organisms in a lichen is so close that lichens are routinely referred to as a single organism, and scientists classify lichens using the name of the fungal component.

(Definitions from: American Heritage Science Dictionary)

Growth Habit

Intro paragraph to be provided by New York.

Vine:	DESCRIPTION TO BE PROVIDED BY NEW YORK.
Shrub:	DESCRIPTION TO BE PROVIDED BY NEW YORK.
Tree:	DESCRIPTION TO BE PROVIDED BY NEW YORK.
Et cetera:	DESCRIPTION TO BE PROVIDED BY NEW YORK.

State Rank

This numeric rank provides the relative rarity for each species based on a scale from 1 (very rare) to 5 (common). These ranks carry no legal status.

S1 - Typically 5 or fewer occurrences, very few remaining individuals, acres, or miles of stream, or some factor of its biology making it especially vulnerable in the state.
S2 - Typically 6 to 20 occurrences, few remaining individuals, acres, or miles of stream, or factors demonstrably making it very vulnerable in the state.
S3 - Typically 21 to 100 occurrences, limited acreage, or miles of stream in the state.
S4 - Apparently secure in the state.
S5 - Demonstrably secure in the state.
SE - State exotic or non-native.
SH - Historically known from the state, but not seen in the past 15 years.
SNA - Species for which a rank is not applicable. This is mainly those species which are now excluded from flora for various reasons.
SNR - Not yet ranked.
SX - Apparently extirpated from the state.

Global Rank

Each species' global rank is determined by NatureServe. These ranks carry no legal weight. The global rank reflects the species worldwide rarity.

G1 - Critically imperiled globally because of extreme rarity (5 or fewer occurrences), or very few remaining acres, or miles of stream) or especially vulnerable to extinction because of some factor of its biology.
G2 - Imperiled globally because of rarity (6 - 20 occurrences, or few remaining acres, or miles of stream) or very vulnerable to extinction throughout its range because of other factors.
G3 - Imperiled globally because of rarity (6 - 20 occurrences, or few remaining acres, or miles of stream) or very vulnerable to extinction throughout its range because of other factors.
G4 - Imperiled globally because of rarity (6 - 20 occurrences, or few remaining acres, or miles of stream) or very vulnerable to extinction throughout its range because of other factors.
G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.
GH - Historically known, with the expectation that it might be rediscovered.
GNA - Species for which a rank is not applicable. NatureServe does not typically rank hybrid species.
GNR - Not yet ranked.
GX - Species believed to be extinct.

Filter by County - Counties to Include - ANY versus ALL

Any - An Any search will combine the list of counties to include with a Boolean Or. Plant species returned will be found within at least one of the selected counties.
All - An All search will combine the list of counties to include with a Boolean And. Plant species returned will be found within each of the selected counties.

Filter by County - Counties to Exclude - ANY versus ALL

Any - An Any search will combine the list of counties to exclude with a Boolean Or. Plant species returned will not be found within at least one of the selected counties.
All - An All search will combine the list of counties to exclude with a Boolean And. Plant species returned will not be found within any of the selected counties.

Associated Ecological Communities

View a List of All Ecological Communities

For more information, contact: Richard Wunderlin or Bruce Hansen, Alan Franck, or Karla Alvarado

Web Development: USF Water Institute

A member of the University of South Florida family of PlantAtlas.org websites

Citation Information:

Wunderlin, R. P., B. F. Hansen, A. R. Franck, and F. B. Essig. 2024. Atlas of Florida Plants (http://florida.plantatlas.usf.edu/). [S. M. Landry and K. N. Campbell (application development), USF Water Institute.] Institute for Systematic Botany, University of South Florida, Tampa.

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Definition: Vouchered Specimen

A voucher specimen is a pressed and thoroughly dried plant sample deposited in a herbarium, and is intended to be a permanent record supporting research purposes. A voucher may be a record of a plant's occurrence in a particular area, or a specific example of a plant used in a scientific investigation.

Proper vouchers display all the necessary attributes for complete identification of the plant, and are to be accompanied by accurate locality, habitat, collection time, and collector data.

Only plant populations vouchered by specimens deposited in Index Herbariorum http://sweetgum.nybg.org/science/ih/ recognized herbaria are represented on this map.