PICKERELWEED

Pontederia cordata

Pickerelweed Family [Pontederiaceae]

month8jun month8june month8jul month8july

status
statusZneophyte
flower
flower8mauve
inner
inner8yellow
inner
inner8white
morph
morph8zygo
petals
petalsZ6
type
typeZspiked
stem
stem8round

7th July 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
A pond into which residents throw out all their unwanted invasive non-native water weeds. Herein lie New-Zealand Pigmyweed, the large-leaved cultivar of Marsh Marigold, Curly Waterweed, Pickerelweed and two native water plants: Fool's-Water-cress and Lesser Bulrush (the tall ones exceeding the height of the photograph).


17th Aug 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
The Pickerelweed plants have upwardly-directed pointed leaves and taller stems with a spike of blue flowers atop. The taller leaves and stems belong to the Bulrush.


17th Aug 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
Your Author missed the flowers at their best, they don't seem to last very long!


17th Aug 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
The spike of flowers is anywhere between 3 and 15cm long (here the shortest your Author thinks) on a round stalk up to 1m tall (here much shorter). The flowers are already turning to the dry brown fruits each containing just one seed. The flowers have 6 petals (actually tepals), 6 stamens and a style with capitate (discoidal) stigma. The tepals have zygomorphic symmetry with three upper tepals, the central one shaped like an Ace of Spades with two yellow ovals surrounded by a broadish white periphery (giving the semblance of two sliced hard-boiled eggs) which slightly overlaps the two outer tepals which are almost linear. The three lower tepals have a stubby central tepal and two outer ones which are broader than the corresponding outer ones in the top half. The rear of the flower is one longish gradually tapering bluish merging to reddish tube.

The flowers have 6 petals (actually tepals) and are 6 to 10mm across. The grow in a dense spike between 2 to 15cm long.



7th July 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
In the centre the triangular-ovate leaves, many of which have a cordate base (heart-shaped). [On the left are the large leaves of the large-leaved cultivar of Marsh Marigold].


8th July 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
The vertical leaves and their stems.


7th July 2017, 4th walled garden, Waterloo, Sefton Coast. Photo: © RWD
Leaves somewhat reminiscent of the spathes on Lords-and-Ladies. The leaves are triangular/oval, between 5 to 25cm long, 0.5cm to 21cm wide with a heart-shaped base and with between 20 and 30 main veins.


Some similarities to : species of Lavender Lavendula which have similarly narrow purple-blue flower spikes but the leaves look nothing like these and they don't grow in fresh water (or any body of water).

Uniquely identifiable characteristics

Distinguishing Feature : The spathe-like vertical leaves.

A cross section of the stems reveals a network of empty parallel channels which allow the free transport of oxygen to the roots and to prevent the anoxic conditions in submerged muds from becoming toxic with microorganism generated components such as sulfide, manganese or iron compounds.

It is a garden pond throwout which can become naturalised at the edges of ponds and found in Northern England down to South Lancashire; also in West Cork, Ireland.

It grows in water up to 1m deep and can be up to 1.3m in length total, so for deeper bodies of water it usually occupies the periphery. The fruit (not shown) is a kidney-shaped capsule with 6 toothed edges. The seeds within the fruits are also kidney-shaped, 3.5 to 4.5mm long by 2 to 2.5mm wide. It is not frost hardy and dies off in winter. Presumably the seeds grow into new plants the following spring.

It was introduced into bodies of water in 1949 and so far mainly occupies the South of England.


  Pontederia cordata  ⇐ Global Aspect ⇒ Pontederiaceae  

Distribution
 family8Pickerelweed family8Pontederiaceae
 BSBI maps
genus8Pontederia
Pontederia
(Pickerelweeds)

PICKERELWEED

Pontederia cordata

Pickerelweed Family [Pontederiaceae]