Trapa bispinosa
(Trapa bispinosa Roxb. var. iinumae Nakano, Trapa natans L. var. bispinosa Makino)
Two-horned Water-Chestnut, Two-horned Trapa
[not native to the Mid-Atlantic area]
[ click on any image below to see larger version ]
Family:
Lythraceae
(Loosestrife family)
Mid-Atlantic bloom time:
June - September
Mid-Atlantic fruit ripe:
July - November
Two-horned Water-Chestnut was first reported in the mid-Atlantic region in 2014 at Pohick Bay, Virginia, on the Potomac River.
This invasive water chestnut, while similar to the Eurasian Water Chestnut (T. natans),
has been found to be genetically and morphologically most similar to samples of
T. bispinosa Roxb. var. iinumae Nakano from Taiwan.
It is unrelated to the sedge Chinese Water Chestnut (Eleocharis dulcis) sold in cans in grocery stores.
Two-horned Water Chestnut differs from T. natans by having reddish/chestnut lower leaf surfaces instead of green,
and light pink petal flowers instead of white.
Its seed pods, called caltrops because of their shape, have 2 horns instead of 4,
hence its species epithet bispinosa meaning "two spines".
T. bispinosa is reported as the only domesticated species of this genus and
is one of popular seasonal edible resources in China, Japan, Taiwan, and Vietnam.
26 July 2024
Fair Lakes, Fairfax County, VA
(rosette of leaves floating on water surface)
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26 July 2024
Fair Lakes, Fairfax County, VA
(some leaves upturned showing reddish-brown undersides)
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26 July 2024
Fair Lakes, Fairfax County, VA
(overturned leaf rosette showin leaf undersides)
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26 July 2024
Fair Lakes, Fairfax County, VA
(showing stem badders)
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26 July 2024
Fair Lakes, Fairfax County, VA
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26 July 2024
Fair Lakes, Fairfax County, VA
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26 July 2024
Fair Lakes, Fairfax County, VA
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26 July 2024
Fair Lakes, Fairfax County, VA
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26 July 2024
Fair Lakes, Fairfax County, VA
(lake partially covered with T. bispinosa)
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26 July 2024
Fair Lakes, Fairfax County, VA
(old caltrops washed ashore)
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26 July 2024
Fair Lakes, Fairfax County, VA
(old caltrop)
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26 July 2024
Fair Lakes, Fairfax County, VA
(bristle detail on old caltrop spine)
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