PURPLE LOOSESTRIFE

SPIKED LOOSESTRIFE

Lythrum salicaria

Loosestrife Family [Lythraceae]

month8jun month8june month8jul month8july month8Aug

status
statusZnative
 
flower
flower8purple
 
morph
morph8actino
 
petals
petalsZ6
(5 - 7)
type
typeZclustered
 
type
typeZtieredwhorls
 
type
typeZspiked
 
stem
stem8square
 
sex
sexZbisexual
 
sex
sexZheterostylous
 

5th Aug 2007. WWT London wetland Centre. Photo: © Roger Hewitt
Loves to grow near fresh water but not in it. Spreads wildly on fens, marshes, less so beside canals and ditches where the opportunity is restricted to a linear path.


1st Aug 2008, In a ditch near Croston, Preston. Photo: © RWD
Making a break for it in an arable field. The ground must be damp there.


2nd Aug 2009, Ex-Windsor High School grounds, Salford, Lancs. Photo: © RWD
Grows up to 1.5m high.


24th July 2013, Moses Gate Country Park, Farnworth, Gtr M/cr. Photo: © RWD
Flower whorls conspicuous on this plant.


20th Sept 2008, Huddersfield Narrow Canal, Uppermill. Photo: © RWD
More mature specimens have branched spikes of flowers.


16th Aug 2005, Cold Heindle, Barnsley Canal. Photo: © RWD
Fully developed flower spikes now apparently lacking whorls.


24th June 2006, Worcester & Birmingham Canal. Photo: © RWD
On young specimens where the flowers have not yet fully developed the whorls of flowers are more easily discerned, being well separated.


24th June 2006, Worcester & Birmingham Canal. Photo: © RWD
The stems and leaves have fine short hairs.


24th June 2006, Worcester & Birmingham Canal. Photo: © RWD
Not yet opened flower buds. The sepal tubes redden under the hot summer sun. Sepal teeth are long. Stems are round to angular, the leaves either in opposite pairs, or in whorls of three.


16th Aug 2005, Cold Heindle, Barnsley Canal. Photo: © RWD
As the plant matures the flower whorls stretch out and the flower-spike become more uniformly covered in flowers.


24th June 2006, Worcester & Birmingham Canal. Photo: © RWD
The petals normally number 6, but 5 or 7 is quite common.


2nd Aug 2009, Ex-Windsor High School grounds, Salford, Lancs. Photo: © RWD
The flowers are heterostylous, meaning that the flowers occur in two or more types, with their styles and stamens being different lengths in comparison to each other. In the case of Purple Loosestrife, which is Tristylous, there are three basic types of flower to be found, each having two sets of six stamens of differing length and a style of yet another length. One morph has a short style and a set of medium length and a set of long stamens; another morph has a medium length style and sets of both long and short stamens; the third morph has a long style with sets of medium and with short stamens. Pollen transferred from flowers of the same morph will not result in fertilization because the individual morphs are self-incompatible. The three flower morphs are adapted to pollination by different insects. Generally, pollen from the nearest stamens will pollinate the stigma that is closest to it. This plant has a very short single style hiding deep within the sepal tube. Two sets of six anthers are longer than the style, the medium-length set has yellow anthers in the photo, the set with darker anthers here are the longest.


24th July 2013, Moses Gate Country Park, Farnworth, Gtr M/cr. Photo: © RWD
Whereas on this plant the single style (with the green 'discus' termination) is longer than the two shorter sets of six stamens, the shortest set almost hidden within the sepal tube. Your Author does not, at present, have photos of the third kind of heterostyly, where the style is of medium length, intermediate in length between the long set of stamens and the short set of stamens. He is open to any photo submissions.


24th July 2013, Moses Gate Country Park, Farnworth, Gtr M/cr. Photo: © RWD
Opposite leaves in quadrature on a square hairy stem, branchlets starting to grow.


24th July 2013, Moses Gate Country Park, Farnworth, Gtr M/cr. Photo: © RWD
Leaves lanceolate, lacking teeth, here in opposite pairs (but can also be in whorls on the same plant).


24th July 2013, Moses Gate Country Park, Farnworth, Gtr M/cr. Photo: © RWD
Stems square in places. Opposite leaves with leafed branches starting to appear above them.


22nd Sept 2010, the resr edge, Blackleach, Walkden, Gtr Mcr. Photo: © RWD
The fruits turn reddish in Autumn.


Some similarities to : Some Woundworts, but the flowers are open and six-petalled. Also superficial resemblance to Butterfly-Bush

Distinguishing Feature :

No relation to : Yellow Loosestrife, Dotted Loosestrife, Fringed Loosestrife, Whorled Loosestrife, Tufted Loosestrife or Lake Loosestrife which all belong to the Myrsine Family whereas Purple Loosestrife belongs to the Loosestrife Family. Confusing? Yes. Obtuse too.

The text-books say that the stems are square, but in some of these photographs they look hexagonal in places, and round in others. Maybe the text-books are averaging 'hexagonal' and 'round' to arrive at 'square'? If they were square, then why are the leaves sometimes in triplets, as the text-book says? Does one side in four lose out to a leaf?

From a distance, a drift of Purple loosestrife can be mistaken for Rosebay Willowherb. In some parts of the World, wetland areas of North America and New Zealand for instance, Purple Loosestrife is an invasive species and subject to control measures. Left to its own devices it will readily spread.


  Lythrum salicaria  ⇐ Global Aspect ⇒ Lythraceae  

Distribution
family8Loosestrife family8Lythraceae

 BSBI maps
genus8Lythrum
Lythrum

PURPLE LOOSESTRIFE

SPIKED LOOSESTRIFE

Lythrum salicaria

Loosestrife Family [Lythraceae]

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