genusTrapa

Trapa natans

Linnaeus

Sp. Pl. 1: 120. 1753.

Treatment appears in FNA Volume 10.
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Stems slender, young growth and flowering parts velutinous. Leaves of floating rosettes bearing successively longer pet­ioles toward outer edges of rosette, to 20 cm; blade 20–40 × 25–60 mm, width greater than length, surfaces velutinous abax­ially, glabrous adaxially. Floral-tube 2 mm; sepals 4–7 mm, keeled; petals obovate, 8–15 mm. Drupes 20–25 mm diam., excluding spines; horns 2–4, to ca. 10 mm. 2n = 48 (Poland, Japan), 96 (Japan).


Phenology: Flowering summer–fall.
Habitat: Relatively neutral, nutrient-rich, flowing or still waters, rivers, ponds, lakes.
Elevation: 0–400 m.

Distribution

Introduced; Que., Conn., Del., D.C., Maine, Md., Mass., N.H., N.J., N.Y., Pa., R.I., Vt., Va., Europe, Asia, Africa

Discussion

Trapa natans was first noted in Massachusetts in 1859 from an unknown origin and was recorded from the Charles River, Cambridge, in 1879. The hard, spiny fruits can cause severe puncture wounds and are slow to decay in lake and river bottoms. The species propagates by seed and by detached floating rosettes to form extensive floating mats that reduce oxygen, restrict light, crowd out native plants, and make navigation difficult. Populations grow rapidly and are difficult to eradicate except by sustained efforts over multiple seasons. Federal regulations now prohibit interstate sale and transport of T. natans. The species is considered rare and threatened in Europe.

Selected References

None.

Lower Taxa

None.

"elongating" is not a number."timesfloral-tubelength" is not declared as a valid unit of measurement for this property.

... more about "Trapa natans"
dehiscent +  and introrse +
C. Barre Hellquist +  and Shirley A. Graham +
Linnaeus +
brochidodromous +
greater than length +
membranous +
2.5 cm25 mm <br />0.025 m <br /> (6 cm60 mm <br />0.06 m <br />) +
photosynthetic +
cordate +, auriculate +, rolled +  and complanate +
large +  and unequal +
persistent +
obconic +, cylindrical +, urceolate +, turbinate +  and campanulate +
Que. +, Conn. +, Del. +, D.C. +, Maine +, Md. +, Mass. +, N.H. +, N.J. +, N.Y. +, Pa. +, R.I. +, Vt. +, Va. +, Europe +, Asia +  and Africa +
indehiscent +, septifragal +, septicidal +, loculicidal +  and dehiscence +
2 cm20 mm <br />0.02 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
2-4-horned +
0–400 m. +
slender +
perigynous +  and semi-epigynous +
campanulate +
2 cm20 mm <br />0.02 m <br /> (?) +
actinomorphic +  and pedicellate +
trichomelike +
Relatively neutral, nutrient-rich, flowing or still waters, rivers, ponds, lakes. +
rosette-forming +
velutinous +  and glabrous +
2 cm20 mm <br />0.02 m <br /> (4 cm40 mm <br />0.04 m <br />) +
hardened +
axillary +  and terminal +
subopposite +  and arranged +
deciduous +
submerged +
toothed +
0 cm0 mm <br />0 m <br /> (20 cm200 mm <br />0.2 m <br />) +
triangular +  and rhombic +
cuneate +, triangular +  and rhombic +
submerged +
pinnately-dissected +  and filiform +
distinct +
inferior +  and semi-inferior +
flowering +  and young +
velutinous +
pinnately-veined +
pale lavender +  and white +
distinct +
obovate +
0.8 cm8 mm <br />0.008 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Flowering summer–fall. +
globose +  and elongate +
abbreviated +
adventitious +
not +  and winged +
alternating +
persistent +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
creeping +  and decumbent +
submerged +
trailing +, spreading +  and erect +
4-angled +
slender +
capitate +  and punctiform +
petiolate +, subsessile +  and sessile +
slender +
not +  and clonal +
aquatic +, amphibious +  and terrestrial +
glabrous +  and velutinous +
Trapa natans +
species +
indurated +, leathery +  and dry +