Freitag, 11. Mai 2012

Plant of the Day (May 12th. 2012) - Prunus laurocerasus L.


Sorry for the long break, but I was sick this week and couldn't write an article.

So, today's “Plant of the Day” is one of the most common evergreen plants in gardens and parks. It's Prunus laurocerasus L. from the Rosaceae family. In Germany, we call this species “Lorbeerkirsche” while in English it's known as “cherry laurel”. In some literature, this species is still known as Laurocerasus officinalis L.

P. laurocerasus - habitus

It's a big shrub, which can reach an average height of 6 metres (but can also reach heights over 10 metres).
The leathery leaves are elipitcal and very simple with an entire margine, which can be a little bit bent. The dorsal site is dark green and shiny, while the ventral site is bright green and with a couple of nectaries at the base of the leaf-blade.

P. laurocerasus - leaves

The function of the leaf-nectaries is the attraction of ants, which eats vermin like caterpillars or aphids, which can injure the leaves.

P. laurocerasus - single leaf (dorsal site)

P. laurocerasus - single leaf (ventral site)

As member of the Spiraeoideae, a sub-family of the Rosaceae, this species has no stipula.

The inflorescences are upright racemes with many small, radial flowers.
Each flower consists of five, bright-green sepals, five white petals and a lot of stamens and carpels. The stamens are very long and much longer than the stylus. There are also nectaries at the ground of the flowers, giving them a orange colour in the centre.
Flowering time is between April and June. The ripe fruit is are black drupes, which are eaten by birds.

P. laurocerasus - inflorescence

All in all, P. laurocerasus looks similar to the real laurel (Laurus nobilis L.).; especially the leaves. This is also the reason for the name “cherry laurel”, but there is no relationship between this two species, because Laurel belongs to the Lauraceae family.

P. laurocerasus - single flower: s = sepals; p = petals;
styl = Stylus; sta = Stamen; n = nectaries

P. laurocerasus is native to Asia minor and grows wild in Anatolia, the Caucasus and North-Iran. It prefers fresh and shady places and grows in the undergrowth of forests in altitudes from sea-level to 2.000 metres. However, P. laurocerasus is also a very popular shrub for gardens and hedges and planted all other the world today as evergreen ornamental plant (however, this plant isn't so robust towards very hard and long periods of frost as some people maybe think).

P. laurocerasus - dryed fruit from the last year

The species can be toxic. Leaves and seeds contain a chemical compound called “Prunasin”. If this Prunasin comes in contact with gastric acid, it can transform into dangerous cyanide. However, Prunasin is in the seed of every cherry (Genus: Prunus); making P. laurcerasus not more toxic as other cherries like Prunus cerasus L. or Prunus avium L.

In Turkey, the pulp of the ripe fruits is even used to make bitter tasting jam. The fruits are also eaten as dried fruits.

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