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Podostemum ceratophyllum

Michx.

Threadfoot

G4Apparently Secure Found in 3 roadless areas NatureServe Explorer →

G4Apparently SecureGlobal Rank

Least concernIUCN

UnknownThreat Impact

Identity

Unique IDELEMENT_GLOBAL.2.149034

Element CodePDPOD01010

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryVascular Plant

IUCNLeast concern

Endemicoccurs (regularly, as a native taxon) in multiple nations

KingdomPlantae

PhylumAnthophyta

ClassDicotyledoneae

OrderPodostemales

FamilyPodostemaceae

GenusPodostemum

Other Common Names

Hornleaf Riverweed (EN) hornleaf riverweed (EN) Podostémon à feuilles cornées (FR)

Concept Reference

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

Conservation Status

Rank Method Rank calculation - Biotics v2

Review Date2024-08-12

Change Date2024-08-12

Edition Date2024-08-12

Edition AuthorsGeoffrey Hall (1998), rev. Johnson, J. (2024)

Threat ImpactUnknown

Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)

Number of Occurrences81 - 300

Rank Reasons

Podostemum ceratophyllum is a perennial aquatic herb found in rivers in the eastern United States and southern Canada. With a large range extent, more than 200 occurrences, and abundant habitat, this species is apparently secure.

Range Extent Comments

Podostemum ceratophyllum is native to the eastern United States and southern Canada (FNA 2015). Additional historical collections from the Caribbean and Central America may represent misidentified individuals of related tropical species. Range extent was estimated using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1993 and 2024 (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).

Occurrences Comments

By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1993 and 2024, it is estimated that there are more than 300 occurrences rangewide (GBIF 2024, iNaturalist 2024, NatureServe 2024, SEINet 2024).

Threat Impact Comments

Podostemum ceratophyllum is thought to be susceptible to pollution in Kentucky but it is common in North Carolina, indicating it may be tolerant (Southern Appalachian Species Viability Project 2002). Dams, road construction and maintenance, and increased sediment transport may also impact its habitat.

Ecology & Habitat

Habitat

Podostemum ceratophyllum grows attached to rocks and bedrock in flowing water (FNA 2015, Native Plant Trust 2024).

Other Nations (2)

United StatesN4

Province	Rank	Native
New Hampshire	SNR	Yes
South Carolina	S4	Yes
North Carolina	S5	Yes
Kentucky	S2	Yes
Delaware	S1	Yes
Louisiana	S1	Yes
District of Columbia	SNR	Yes
Oklahoma	S2	Yes
New York	S2	Yes
Massachusetts	S2	Yes
Tennessee	SNR	Yes
Vermont	S1	Yes
New Jersey	S2	Yes
Alabama	SNR	Yes
Connecticut	S3	Yes
West Virginia	S2	Yes
Maryland	S3	Yes
Georgia	SNR	Yes
Maine	S3	Yes
Virginia	S5	Yes
Mississippi	S4	Yes
Arkansas	S3	Yes
Ohio	S1	Yes
Pennsylvania	S4	Yes
Rhode Island	S2	Yes

CanadaN3

Province	Rank	Native
Ontario	S2	Yes
Quebec	S3	Yes
New Brunswick	S3	Yes
Nova Scotia	S1	Yes

Threat Assessments

Threat	Scope	Severity	Timing
4 - Transportation & service corridors	Unknown	Unknown	Unknown
7 - Natural system modifications	Unknown	Unknown	Unknown
7.2 - Dams & water management/use	Unknown	Unknown	Unknown
9 - Pollution	Unknown	Unknown	Unknown

Plant Characteristics

DurationPERENNIAL

Economic Value (Genus)No

Roadless Areas (3)

Alabama (1)

Area	Forest	Acres
Oakey Mountain	Talladega National Forest	6,129

North Carolina (1)

Area	Forest	Acres
Bald Mountain	Pisgah National Forest	11,085

South Carolina (1)

Area	Forest	Acres
Big Mountain	Sumter National Forest	2,337

References (8)

Flora of North America Editorial Committee (FNA). 2015. Flora of North America north of Mexico. Vol. 6. Magnoliophyta: Cucurbitaceae to Droserceae. Oxford University Press, New York. 496 pp + xxiv.
Global Biodiversity Information Facility (GBIF). 2024. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2024).
iNaturalist. 2024. Online. Available: https://www.inaturalist.org (accessed 2024).
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Native Plant Trust. 2024. Go Botany website. Online. Available: https://gobotany.newenglandwild.org (accessed 2024).
NatureServe. 2024. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
Southern Appalachian Species Viability Project. 2002. A partnership between the U.S. Forest Service-Region 8, Natural Heritage Programs in the Southeast, NatureServe, and independent scientists to develop and review data on 1300+ regionally and locally rare species in the Southern Appalachian and Alabama region. Database (Access 97) provided to the U.S. Forest Service by NatureServe, Durham, North Carolina.
Southwest Environmental Information Network (SEINet). 2024. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2024).

Podostemum ceratophyllum

Habitat

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