| Crassula helmsii | |
|---|---|
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Saxifragales |
| Family: | Crassulaceae |
| Genus: | Crassula |
| Species: | C. helmsii |
| Binomial name | |
| Crassula helmsii (T.Kirk) Cockayne |
|
Contents |
Swamp Stonecrop, New Zealand Pigmyweed
Tillaea recurva, Tillaea Helmsii, Crassula recurva
Originally found in Australia and New Zealand, it has been introduced around the world. In the UK it is considered an invasive species.
The shoots are rather stiff, carrying narrow parallel-sided leaves in opposite pairs, each leaf being about 4-24mm. 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.
The plant grows on the muddy margins of ponds where it forms carpets with 100% cover, or semi-submerged in deeper water, or totally submerged with elongated stems. It does not die back in winter.[1]
C. helmsii is able to grow fully submerged in a cool water aquarium or as a submersed or marginal plant in a pond. Once established it can grow vigorously and may need to be trimmed back. Schedule 9 of the UK Wildlife and Countryside Act 1981 lists this plant as one that cannot be caused to grow in the wild.