NEW-ZEALAND PIGMYWEED

AUSTRALIAN SWAMP STONECROP

Crassula helmsii

Stonecrop Family [Crassulaceae]  

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status
statusZalien
flower
flower8white
morph
morph8actino
petals
petalsZ4
stem
stem8round

23rd June 2008, Teal Scrape, Pennington Flash, Wigan. Photo: © Paul Breslin
An aggressive alien invader of still freshwaters, usually throw-outs from garden ponds. the elongated brown heap in the foreground looks like previous attempts at raking the lake and getting rid of this highly-invasive plant.


14th June 2006, Manchester Airport Pond. Photo: © Paul Breslin
It is a mostly submerged perennial, occupying shallow waters and stranded on mud.


26th Oct 2007 Photo: © Paul Breslin
Forms a thick carpet with reddish stems up to 30cm long and short pointed green leaves.


26th Oct 2007 Photo: © RWD
The flowers are tiny, just 1-2mm across.


14th June 2006, Manchester Airport Pond. Photo: © Paul Breslin
Flowers have four almost equilateral-triangular petals.


26th Oct 2011, Fernilee Resevoir, Whaley Bridge, Derbys. Photo: © RWD
Leaves short and fleshy, mostly in opposite pairs up a fleshy reddish stalk.


8th July 2017, Park Gardens, Waterloo, Sefton Coast Photo: © RWD
Some flowers on longish stalks emerging just above the leaf nodes.


26th Oct 2011, Fernilee Resevoir, Whaley Bridge, Derbys. Photo: © RWD
Un-opened flower buds are pinkish. The fruits are in four segments and greenish at first.


26th Oct 2011, Fernilee Resevoir, Whaley Bridge, Derbys. Photo: © RWD
The flowers have four white petals and four stamens bearing yellow pollen.


26th Oct 2011, Fernilee Resevoir, Whaley Bridge, Derbys. Photo: © RWD
An as-yet un-opened flower, 4 petals still to unfold (top centre). In autumn the leaves go brownish.


8th July 2017, Park Gardens, Waterloo, Sefton Coast Photo: © RWD
The anthers have opened into red Ace-of-Spades shapes, now lacking pollen. Sepals and Petals alternate. Flowers on longish stalks which emerge above leaf-nodes.


8th July 2017, Park Gardens, Waterloo, Sefton Coast Photo: © RWD
The 4 white styles as pillars in the centre.


8th July 2017, Park Gardens, Waterloo, Sefton Coast Photo: © RWD
The flower stalk merges into a widening sepal-cup. Many flowers have pink-tinged petals.


8th July 2017, Park Gardens, Waterloo, Sefton Coast Photo: © RWD
Four developing pale-green fruits in the centre, each with a style still attached. Tiny black flies on leaves.


Distinguishing Feature : Easily distinguished from another stonecrop called Pygmyweed (Crassula aquatica) which has tiny 1-2mm flowers and grows to 5cm and found only on the shores of Loch Shiel, Scotland, whereas New-Zealand Pigmyweed is found in many places south of the Forest of Bowland.

This is another problematic plant in that it quickly invades any still freshwater where it has been discarded by aquatic gardeners, to the detriment and ultimately entire exclusion of all other aquatic plants and fish in the pond.

An aquatic plant that is usually submerged, but sometimes becomes stranded on muddy shores. It was virtually un-known in Britain two decades ago.


  Crassula helmsii  ⇐ Global Aspect ⇒ Crassulaceae  

Distribution
family8Stonecrop family8Crassulaceae

 BSBI maps
genus8Crassula
Crassula
(Pigmyweeds)

NEW-ZEALAND PIGMYWEED

AUSTRALIAN SWAMP STONECROP

Crassula helmsii

Stonecrop Family [Crassulaceae]  

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