They are linear to oval in shape, becoming increasingly fleshy in shallow water or in emergent and terrestrial forms. It was first sold as an oxygenating plant in 1927. Washington State Noxious Weed Control BoardCABI Invasive Species Compendium information on Please see WAC 16-752 for more information on the quarantine list. This is known as 'Crassulacean Metabolism'.

A three-phase project was undertaken in 2012 to control C. helmsii on Mile Cross Marsh.

New Zealand pigmyweed (Australian swamp-stonecrop) Crassula helmsii. )Australian Swamp Stonecrop, Crassula helmsii, is an aquatic or semi-terrestrial species of succulent plant, first introduced to Britain from Tasmania in 1911. Australian swamp stonecrop. These provisions, whilst making it illegal to plant or cause the plant to grow in the wild, would, in the long run, also be likely to end any further commercial sale.Australian Swamp Stonecrop; New Zealand Pygmy-weed, Crassula.The results of this remarkable adaptation are twofold. The UK experience of this plant seems far worse than in its Australasian native range, or the numerous Europaean localities where it occurs. Australian swamp stonecrop Crassula helmsii. The water can be alkaline, acid, or even slightly salty. Sizes range from 4 to 24mm in length and 0.7 to 1.6mm in width. Whilst being aware that large masses of dead plant material in a water body can lead to further deoxygenation, at least 70% of a large colony should be treated at once to avoid spread back from the untreated area. The first occurrence in the wild was reported in Essex in 1956. (Seeds are not thought to be produced in the UK. Other Common Names: New Zealand pigmyweed Weed class: noClass Native to: Australia and New Zealand Legal listings: This plant is on the quarantine list. Its leaves are pale green, in opposite, sessile or connate pairs, arranged alternately. Such cover must be kept on for at least 8-10 weeks, with 6 months being desirable. Crassula helmsii. It must be remembered that Glyphosate, unlike the now proscribed Diquat, does not work at all if actually applied in water or to wet material.For submerged infestations, Dichlobenil granules should be employed during the early part of the growing season during February and March.Two herbicides are still approved for use in the UK, though both are non-selective and harmful to desirable species. As water depth decreases, the stems become more succulent and branched, with internodal lengths shortening. 3 If not a single taxonomic entity, can it be redefined? Originally found in Australia and New Zealand, it has been introduced around the world. In water of greater than 60cm depth, the stems are thin and barely succulent with long internodes. Stems are coloured yellowish-green, and are of round section. Warren and Gloria Sheather. It was subsequently dispersed by the nursery trade, first being sold as an oxygenating plant in 1927.

Crassula helmsii is listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales therefore, it is also an offence to plant or otherwise cause to grow these species in the wild.

Most plants absorb Carbon Dioxide through the stomata on the leaves during the hours of daylight, so that the light-dependant energy manufacturing process known as photosynthesis can take place. It is necessary for the plant material sprayed to be dry in order for the Glyphosate to be absorbed and translocated. In the United Kingdom, this plant is one of five introduced invasive aquatic plants which were banned from sale from April 2014.

In New Zealand the species is known as Pygmyweed.

Australian swamp stonecrop. Fruits contain 2 to 5 elliptical, smooth seeds about 0.5mm long. This pond plant grows either on the muddy bog margins of ponds where it forms carpets and can also be total submerged in deeper water of ponds and grown as an oxygenator. Taxonbars with automatically added basionymsThe shoots are rather stiff, carrying narrow parallel-sided leaves in opposite pairs, each leaf being about 4–24 millimetres (0.16–0.94 in). This contributes to its super-rapid growth and ability to develop the vast biomass, which smothers all competitors.The ability to move from aquatic to terrestrial life is facilitated by its metabolic twist. U.S. Weed Information.

In freshwater wetlands of North-western Europe, this alien plant species is invasive due to its efficient colonization of empty niches. Australian Swamp Stonecrop is an aquatic to semi-terrestrial evergreen perennial. swamp stonecrop.

Other Common Names: New Zealand pigmyweed Weed class: noClass Native to: Australia and New Zealand Legal listings: This plant is on the quarantine list. European and Mediterranean Plant Protection Organization data sheet on GB non-native species secretariat information on U.S. (if necessary use the response box to re-define the organism and carry on) N/A 4 Describe the organism. Your Name Email Address. The flowers are always above water. Crassula helmsii (Australian swamp stonecrop or New Zealand pygmyweed) was first recorded growing on Mile Cross Marsh in Norwich, Norfolk, UK before 2003. Back to Plant Database