Species description (Flora Helvetica 2018)

Im Wasser stehend. Blätter grundständig, etwa zur Hälfte aus dem Wasser ragend, schwertförmig, steif, 10-40 cm lang und 0,5-3 cm breit, unten 3kantig, oben flach, mit vorwärts gerichteten, stacheligen Zähnchen. Pflanze zweihäusig. Blüten auf blattlosem, dickem Stängel, von einer Spatha umgeben. Perigonblätter 6, 3 innere weiss, rundlich, Durchmesser ca. 2 cm, 3 äussere kelchartig, grün.

Flowering period (Flora Helvetica 2018)


Habitat and distribution inside Switzerland (Flora Helvetica 2018)

Stehende oder langsam fliessende, warme und nährstoffreiche Gewässer / kollin / M und ANE, sich einbürgernd

World distribution (Flora Helvetica 2018)


Ecological indicator (Landolt & al. 2010)


Distribution map


Before threshold year
After threshold year
Before and after threshold year


Validated observations
Observations waiting for validation
Occurrences from Atlas Welten & Sutter (1982) and supplements (1984, 1994) without confirmation in the Info Flora database since
Before threshold year
After threshold year
Not native / introduced / subspontaneous / escaped

Number of observations

Below the threshold number of observations
Above or equal the threshold number of observations


Life form



Habitats Delarze & al. 2015

Character species 1.1.3 - Wasserlinsengesellschaften (Lemnion)

bold Dominant species, influencing the appearance of the habitat
Character species Character species
Less strictly linked to a specific habitat Less strictly linked to a specific habitat

Ecological indicator values by Landolt & al. (2010)

Soil factors Climatic factors Salinity tolerance
Humidity Value H 5u Light Value L 3 Salinity Index 1
Reaction Value R 2 Temperature factor T 3+
Nutriments value N 3 Continentality K 4
  • Ecological values legend
    Humidity Value H
    1very dry
    2moderatly dry
    3medium wet
    4very wet
    5submerged or underwater
    fplants living in running water
    umostly submerged plants
    vpartly submerged, partly floating plants
    whumidity moderately variable (± scale of 1-2)
    w+highly variable humidity (scale exceeding ± 2)
    Reaction Value R
    1Very acid (pH 2.5-5.5)
    2acid (pH 3.5-6.5)
    3lightly acid to neutral (pH 4.5-7.5)
    4neutral to basic (pH 5.5-8.5)
    5basic (pH 6-5 -> 8.5
    Nutriments value N
    1very low in nutrients
    2low in nutriments
    3medium-poor to medium-rich in nutrients
    4rich in nutriments
    5very rich in nutriments
    Salinity tolerance
    Light Value L
    1very shady
    3lighted areas
    5highly luminous
    Temperature factor T
    1alpine to nival stages (from the treeline to the snowline)
    1+suprasubalpine and upper subalpine levels (pine and larch forests)
    2subalpine level (coniferous forests without beeches up to the upper limit of spruces)
    2+lower subalpine and upper mountain stages
    3mountain level (beech and silver fir forests, in the central Alps Scots pine forests)
    3+lower mountain and upper hill levels
    4hill level (mixed deciduous oak forests)
    4+hot places, hill level
    5very hot places, hill level (only in the hottest places, typical of southern Europe)
    Continentality K
    1Atlantic (high air humidity, very low temperature variations, mild winters)
    2Sub-Atlantic (high air humidity, low temperature variations, relatively mild winters)
    3sub-Atlantic to subcontinental (average air humidity, moderately variable temperature, slightly low winter temperatures)
    4subcontinental (low air humidity, large temperature variations, rather cold winters)
    5continental (very low air humidity, very large temperature variations, cold winters)


Vernacular name

Deutscher Name:
Krebsschere, Wassersäge
Nom français:
Stratiotès aloès
Nome italiano:
Erba coltella dei fossi, Scargia

Match with other reference books

Relation Nom Book No
=Stratiotes aloides L.Checklist 2017409700
=Stratiotes aloides L.Flora Helvetica 20012384
=Stratiotes aloides L.Flora Helvetica 20122376
=Stratiotes aloides L.Flora Helvetica 20182376
=Stratiotes aloides L.Index synonymique 1996409700
=Stratiotes aloides L.Landolt 1977159
=Stratiotes aloides L.Landolt 1991150
=Stratiotes aloides L.SISF/ISFS 2409700

= The taxon corresponds to the accepted taxon (Checklist 2017)
< The taxon is included in the accepted taxon (Checklist 2017)
> The taxon includes (among others) also the accepted taxon (Checklist 2017)


Native status   -  -


Images and descriptions (© Fritz H. Schweingruber & Hugo Berger)

text alt Stems, 100x
text alt Stems 400x

Summary of stem anatomy (German)

Umriss rund oder oval. Grosse, unregelmässige Intercellularen. Epidermiszellen verholzt.


Culm-diameter 2-5 mm, wall very large, radius of culm in relation to wall thickness approximately 1:0.75. Outline circular with a smooth surface. Center hollow and surrounded by many large thin-walled, not lignified cells. Without cortex/cylinder separation. Culm without endodermis but with a sheath of lignified cells around the center. Epidermis smooth. Epidermis cells thin-walled all around. Large vascular bundles arranged in one peripheral row. Chlorenchyma present, continuous peripheral belt with unlignified round cells (like a large cortex). Sclerenchyma belt in a large, peripheral continuous belt (> 3 cells). Cells thick-walled. Vessel arrangement radial. Largest vessel in the bundle 20-50 μm. Aerenchyma (intercellulars) between parenchyma cells irregular and large.