Sonntag, 23. Oktober 2011

Plant of the Day (October 23th, 2011) - Impatiens glandulifera Royle

Today's entry is about Impatiens glandulifera Royle from the Balsaminaceae family. Its most common German name is “Drüsiges Springkraut” or “Indisches Springkraut”, while in English, you know it as “Himalayan Balsam”.

I. glandulifera - habitus

It's a fast growing, annual plant, that can reach heights until 2 metres (6.56 feet), which is very high for an annual plant. The long leaves are opposite in the lower region of the stalk and whorled in the upper regions. They're oval to lanceolate with strongly serrated edges. Leaf-stalk and the Leaf-base are glandular and covered with many, long stalked glands, what also gave the plant its Latin name (“Glandulifera” means “rich of glands”).

I. glandulifera - stock

Another characteristic feature of this plant are its big, zygomorphous flowers, which are the reason for names like “Wupper orchid”, “Bobby Tops” (based on the helmets of British police officers) or “Gnome's hatstand”. They consists of three sepals and five petals. The lower sepal, which looks like a petal, is extended to a long spur. One petal is much bigger then the rest. The inflorescence is a raceme.

I. glandulifera - flowers, capsules and a bee

Because of their scent and the purple colour, the flowers of I. glandulifera are very attractive for bees, which became the most important pollinator of this species. Another reason are the high content of (average sweet) nectar and the very sweet-tasting pollen.

The fruits are small capsules with many seeds within (between 16.000 and 40.000 seed). These capsules are sensitive to pressure and even the slightest touch (e. g. by a raindrop) is enough to bring them to burst. The seeds are flung away with high speed. This kind of spreading is typical for the genus Impatiens and is responsible for the German name of the genus (“Springkraut” means “jumping herb”)

I. glandulifera - flowers, leaves and capsules

Like its English suggest, I. glandulifera is native to India and the Himalayas but today, it can be found as neophyte also in Europe and North America (it looks similar to an orchid, so it was a very popular ornamental plant). However, today it is one of the most invasive plant of Middle Europe. Because of its fast growing rate and many seeds, I. glandulifera is highly competitive against other species and can displace them easily.

I. glandulifera prefers nutrient-rich and wet soils, so it can be found at riverbanks, ruderal wastelands or the edges of woods and many other places with a high anthropogenic import of nitrogen

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