Dienstag, 19. Juli 2011

Plant of the Day (July 19th, 2011) - Fallopia japonica (Houtt.) Ronse Decr.

Hello everybody.. After a longer break, I am back again with a new Article.

This time, I want to show you one of Germany's most problematic plants. And no, it's not because of this plant is toxic. It's just only an extremely fast growing plant, which can invade biotopes very fast and overgrow them easily. Of course, I'm speaking of Fallopia japonica (Houtt.) Ronse Decr. from the Polygonaceae family. In German, this plant is called “Japanischer Flügelknöterich” and in English “Japanese Knotweed”.

F. japonica - habitus

It's a big shrub, which can reach heights until 3 metres (or 9,8 feet). The stalk is textured red and hollow inside. The leaves are alternate and have a very characteristic leaf-blade with a small tip and a nearly straight bottom. Their leaf-stalks are red.

F. japonica - leaf

The inflorescences are panicles with many flowers. Each flower has five, white petals with three stigmas or eight stamens (the plants are dioecious, so we've only male or female individuals).

F. japonica - leaf

As the name suggest, this plant is native to Japan, but can also be found in China or Korea. During the 19th century, it was brought to Europe as ornamental and food plant for cattle and deer. Since then, F. japonica has spread rapidly over Europe and from there also in other parts of the world like North America.

F. japonica - shoot (look at the reddish texture)

The plant uses its rhizomes for vegetative propagation; the generative way plays a minor role. In this way, the plant is able to form large stocks very quickly. The rhizomes are very resistant towards frost or dryness, while the whole plant is undemanding towards its soil. So, you can find F. japonica on many different places like roadsides, ruderal wastelands or parks. I found two exemplars in my neighbourhood, one in Bochum, Western Germany and many in Solingen, also Western Germany.

F. japonica - here you can see the 
hollow inside of the shoot

Because of this properties, F. japonica has become one of the most problematic neophytes of the world. The species is able to displace other plants and to destroy the biodiversity of an ecosystem. In many countries, F. japonica is combated to prevent its spread. However, it's still a popular garden plant In Switzerland, the possession and the sale of this plant is forbidden.

 F. japonica - stock beneath trees

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