Freitag, 13. Juli 2012

Plant of the Day (July 13th, 2012) - Salix alba L. var. alba

Today's “Plant of the Day” is Salix alba L. from the Salicaceae family. The English name of this species is “White willow” and in German, it is called “Silber-Weide” (silver willow). It's also the largest willow in Germany.

S. alba - leaves, bark and brances

It's a tree, which can reach heights until 35 metres (114.8 feet). So, S. alba is one of only a few willows, which grow as trees (the most willows are large shrubs). The bark is greyish and deeply furrowed. Young branches are very elastic and have a yellowish to brown colour. They are also hairy, but loose these hairs, when they get older

The leaves are lanceolate with the widest point in the middle of the leaf-blade. Their dorsal side is covered with some small, white hairs. The ventral side is much hairier than the dorsal side; the hairs are also much longer. Because of this, the leaves seem to shimmer silver. The margin is a little bit serrated and all leaves have a petiole, which is until 5 millimetres long.

S. alba - leaves (dorsal & ventral side)

S. alba is dioecious, so we have male and female individuals. However, in both cases, the inflorescences are cylindrical catkins with a maximum length of 7 centimetres The stamens have a hairy base and the carpels are bald and short-stemmed or sitting, which is different from plant to plant. The bracts are yellow and hairy at the base but bald at the top. Flowering time is between April and May. The ripe fruits are spread out by the wind in June.

S. alba - female catkin

This species is native to Europe, Central Asia and North Africa. It grows in wet, flooded areas like riparian forests, riverbanks or oxbow lakes. As you can think, S. alba prefers sandy, nutrient-rich soils and bright places to grow. It's also a very popular ornamental tree for parks or cemeteries. In this case, the most popular sort of S. alba is “Tristis” (“weeping willow”) with its strong overhanging branches, which symbolize mourning.

The bark of S. alba contains Salicin, which is a very good analgesic. So in earlier times, the bark was used to cure illnesses like rheumatism, gout and even fever. The pliable branches are also used for basket weaving.

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