Montag, 22. Oktober 2012

Plant of the Day (October 22nd, 2012) - Epilobium hirsutum L.

Today's “Plant of the Day” is Epilobium hirsutum L. from the Onagraceae family. In English, this species is known as “Great hairy willowherb” and in German as “Zottiges Weidenröschen”.

E. hirsutum  in its natural habitat

Its a large perennial plant, which can reach heights between 50 and 150 centimetres (19.7 to 59.1 inches). The name hirsutum (Latin for “hairy”) refers to the stalk, which is very hairy. While the lower parts are covered with long hairs, the upper regions contrast with short glandular hairs. The stalk is nearly round.

E. hirsutum - Stalk with hairs

The leaves are long and lanceolate. The upper leaves follow the decussate leaf-pattern; the lower leaves are alternating. They have a serrated margin, wherein the teeth are directed towards the tip. Their leaf-bases encircle the stem completely. The leaves are also covered with hairs. This covering ranges from almost bald over fleecy to felty.

 E. hirsutum - leaves

The inflorescences are simple cymes with large, radial flowers (4 to 8 centimetres in diameter). There are four sepals and four petals. The petals are heart-shaped and have a bright, purple colour. Flowering time is between June and September. The young fruits are long capsules, which are also hairy but they become bald with age. The seeds are very light and are able to swim. This is also the main mechanism of spreading.

E. hirsutum - flower (here you can also see the stamens
and the fourd divided stigma in the centre)

The plant also have a rhizome, which is used for vegetative spreading. This Rhizomes are uneatable for the cattle. Therefore, E. hirsutum grows very quick on meadows.

E. hirsutum is native to the “Old World” (Europe, Asia and North Africa) but can also be found in North America and Australia as Neophyte. The species prefers wet and warm places and can be found at the shores of lakes, swamps and even ditches. It grows also on fresh meadows. It's a very common plant.

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