Freitag, 27. Mai 2011

Plant of the Day (May 27th, 2011) - Robinia pseudoacacia

So, today’s “Plant of the Day” is a very beautiful, interesting but also sometimes problematical shrub: Robinia pseudoacacia L., the “Black Locust” or “Pseudo Acacia” in English and the “Gewöhnliche Robinie” or “Silberregen” in German.

 R. pseudoacacia - habitus

This plant belongs to the Fabaceae family. It's not the first Fabaceae in this Blog; this was Trifolium medium L., which I've shown you earlier.

R. pseudoacacia is a big shrub or tree, which can reach heights between 15 and 25 metres (or 49 – 99 feet). The leaves are pinnate and each of the grass-green leaflet is egg-shaped. The brown bark is deeply furrowed. It contains coumarin.

 R. pseudoacacia - leaf

Like all species of the Fabaceae, R. pseudoacacia has the typical, cygomorphic flowers of this family with different shaped petals: the “banner”, the “keel” (the two fused bottom petals) and the “wings”. The whole flower is white; the inflorescence is a raceme.

 R. pseudoacacia - raceme and flowers

Originally, Robinia pseudoacacia L. was native to North America, especially to the Appalachian Mountains and the East Coast of the USA. Later it came to Europe as Neophyte spread out very quickly. So today, you can find this species on many different places like gardens, parks but also ruderal wastelands, e. g. at old, abandoned train tracks.

 R. pseudoacacia - habitus

The reason for its high modesty is very simple. As a Fabaceae, R. pseudoacacia is able to fix atmospheric nitrogen through a symbiosis with symbiotic bacteria. So, the species can grow better and faster than its competitor and alsoon the most soils. This is a good but also a problem.

It's a good, because R. pseudoacacia is the perfect plant for renaturing industrial or urban wastelands (for example after World War II, one of the first plants in the ruins of German cities was R. pseudoacacia).

However, this can also become a problem, Because of its competitive strength, R. pseudoacacia can be an invader, which invades Biotopes and displace other species.

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