Samstag, 27. Oktober 2012

Plant of the Day (October 27th, 2012) - Lythrum salicaria L.

Today's “Plant of the Day” is Lythrum salicaria L. from the family with the same name: the Lythraceae. In English, this species is known as “Purple loosestrife” and in German, it's called “Gewöhnlicher Blutweiderich”.

L. salicaria - habitus

L. salicaria is a perennial plant, which can reach heights between 50 and 100 centimetres (19.7 to 39.4 inches) but larger individuals with 200 centimetres (78.7 inches) are also possible. The stalk grows upright and is only branched in its lower regions. In this region, there are also some hairs, but the rest is bald.

The leaves are narrow to lanceolate. They sit directly at the stalk and have heart-shaped leaf-bases. Leaves of lower regions follow the decussate leaf-pattern, while the leaves of the upper regions follows the alternating leaf-pattern. Another feature are the protruding leaf-veins.

L. salicaria - leaf and leaf-vein

L. salicaria is a hemi-cryptophyte with a creeping rhizome.

The inflorescences are fake ears (actually a Dichasium), with many small flowers. Flowering time is between July and September. Each flower has six long and narrow petals, which have a deep purple colour.

L. salicaria - inflorescence

It's also interesting, that the stamen and the stylus of each plant may vary in their length. The three main types are
  • long stylus and short stamens
  • medium long stylus and short stamens
  • short stylus and long stamen
The function of these different lengths was unknown for a long time, but Charles Darwin found, that the pollination of individuals with the same lenght was much more successful than in species of different one.

The ripe fruits are capsules with a lot of seeds within it. The seeds are covered with small hairs, which allows them to hold on ducks and other waterbirds for spreeding.

 L. salicaria - flowers ("short stylus" type)

L. salicaria is native to Eurasia, North Africa and Europa but can also be found as neophyte in North America as neophyte. It grows on warm and wet places. Such places are wetlands, riverbanks or flood area. However, the species is also very common on ruderal wastelands and roadsides. It's rare in the highlands.

The species was also used as medicinal plant. All parts of the plant, especially the Rhizome and the stalk, contains Salicarin and other ingredients, which have a haemostatic effect. Because of this, L. salicarium was used to stop bleeding.

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