Trapa bispinosa Roxb.

Locations ofTrapa bispinosa Roxb. in Virginia

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Detail

Family
Lythraceae
Botanical Name
Trapa bispinosa Roxb.
Common Name
Two-horned Water-Chestnut, Two-horned Trapa
Synonym(s)
Trapa natans L. var. bispinosa (Roxb.) Makino
Flora of Virginia Name/Status
Not in Flora of Virginia; discovered after its publication.
Comments
This species was first discovered in the Potomac River watershed in 1995 and has since been found at nearly 50 sites, many of which are being managed to control its spread. Similarity to Trapa natans allowed this species to go undetected until fruit differences were discovered and molecular work conducted. This two-horned taxon has been found to be genetically and morphologically most similar to samples of Trapa bispinosa Roxb. var. iinumai from Taiwan (Chorak et al. 2019. Cryptic introduction of water chestunt (Trapa) in the northeastern United States. Aquatic Botany 155: 32-37.) Rybicki (pers. comm.) indicates that all reports of Trapa in our area from the 1950s and earlier are of Trapa natans, but all recent reports are referrable to bispinosa. Recent reports of T. natans in the Digital Atlas may therefore be T. bispinosa.
Habitat
Artificial ponds and lakes with the exception of an occurrence at Pohick Bay Regional Park.
Native Status
Introduced

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