Swamp stonecrop

Crassula helmsii

''Crassula helmsii'', known as swamp stonecrop or New Zealand pigmyweed, is an aquatic or semiterrestrial species of succulent plant in the family Crassulaceae. Originally found in Australia and New Zealand, it has been introduced around the world.
Swamp stonecrop (Crassula helmsii) The swamp stonecrop is considered an invasive species in the Netherlands (as in a number of other countries). The first observation was in the Netherlands was in 1995. Control of watercrassula is deemed necessary: ​​every 10% increase in watercrassula results in a 5% decrease in native vegetation and has also been shown to have a negative impact on native zooplankton and fauna. (source: https://www.naturetoday.com/intl/nl/nature-reports/message/?msg=23106 - Dutch) Crassula helmsii,Geotagged,Netherlands,Summer,Swamp stonecrop,flora

Appearance

The shoots are rather stiff, carrying narrow parallel-sided leaves in opposite pairs, each leaf being about 4–24 millimetres. Small white flowers with four petals are produced in summer on long stalks arising from the upper leaf axils. The flowers are always above water.

Distribution

This plant from New Zealand has recently been recorded in waste ground waste site in Ireland at Howth Head, County Dublin.

Status

In the United Kingdom, this plant is one of five introduced invasive aquatic plants which were banned from sale from April 2014. This is the first ban of its kind in the country. It is on the Global Register of Introduced and Invasive Species of eleven countries.

References:

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Taxonomy
KingdomPlantae
DivisionAngiosperms
ClassEudicots
OrderSaxifragales
FamilyCrassulaceae
GenusCrassula
SpeciesC. helmsii
Photographed in
Netherlands