Montag, 10. September 2012

Plant of the Day (September 10th, 2012) - Taraxacum officinale agg.

The short series of articles about the Asteraceae tend to an end. But before the series'll end with a final article about the inflorescences of the Asteraceae, we look today at a second, well-known species of the subfamily Cichorioideae. This species is Taraxcum officinale agg.; known as “Gewöhnlicher Löwenzahn” in German 1) and as “common dandelion” in English. This species is very versatile and has many, genetic varieties. Therefore, I will introduce the species generally.

Taraxacum officinale - habitus

T. officinale is a small to medium seized herbaceous plant, which can reach heights between 5 and 40 centimetres (2.0 to 15.7 inches). The hollow stalk is very short and completely leafless; all leaves are arranged in a rosette. These leaves are arrow-shaped and have sharp lobbed margins. The stalk also contains a milky white liquid.

Taraxacum officinale - rosette

This liquid contains Taraxacin, which is a little toxic. High doses can cause skin irritation, liver problems and urination. However, Taraxacin is also used in Homeopathy as laxative.

The inflorescence is one terminal head at the end of a long petiole, which is often mistakenly referred to as stalk As member of the Cichorioideae, all flowers are cygomorphic, tubular flowers with golden yellow petals. Flowering time is between April and July, what makes T, officinale to a important plant for bees. The fruits are winged nuts (Archenes), which are typical for dandelion. However, the “Pusteblume” is not specific for this species. The Archene a very common fruit type of the Asteraceae, which use wind for distribution.

Taraxacum officinale - inflorescence

T. officinale is native to Asia and Europe, but can be found in the whole northern hemisphere as Neophyte today. However, the species is rare in the southern hemisphere and here only as Neophyte. It prefers fresh, nutrient-rich soils and can be found at roadsides, on pastures, in parks and meadows.

Taraxacum officinale - habitus

As I said it before, the species is very diverse and there are many different sorts and varieties. Some scientist believe, that there are over thousand different sorts of this species. Therefore, the species is often stated as Taraxacum sect. Ruderalia in modern literature.

1)The Genus of Taraxkum isn't the only one of the Asteraceae, which is called “Löwenzahn” (Lion's tooth) in German. The other Genus is Leontodon which is known as “Hawkbits” in English. The reason for the same name is the fact, that the species of the Genus Leotodon looks very similar to Taraxacum. However, the petiole of Leotodon species isn't hollow and their Archenes are not arranged at the end of a long stalk.

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