Crassula helmsii New Zealand Pigmyweed

An aquatic or semi-aquatic species that occurs in slow-flowing, nutrient-poor or mesotrophic waters. Sometimes it occurs completely submerged but often it produces emergent, upright shoots. The small succulent leaves are aranged in opposite pairs and emergent shoots produce white, 4-petalled flowers in summer; fully submerged plants do not produce flowers. It is native to Australia and New Zealand and was introduced to Britain by aquarists in 1927. It became naturalised as a result of deliberate planting in ponds and from discarded throw-outs and was susequently recorded wild in Britain in 1956. Since then it  has spread rapidly and is now widespread throughout much of the southern half of Britain. Plants rarely produce any seed, so reproductive spread is almost entirely vegetative. It has a scattered distribution in West Glamorgan with significant colonies in Broadpool and the Neath Canal. Most people regard it as an invasive species.

Neophyte