Sunday, December 7, 2014

White Rock Rose

The white rockrose is a rare cistus that grows in two or three locations in Malta and in Gozo. It is closely related to the hoary rockrose which has larger pink flowers.

This species is found in southern Europe and North Africa. It grows in typical Mediterranean terrestrial habitats including forests, woodlands, maquis and garigue. It is often cultivated as a garden plant and in some parts of the world it has escaped from cultivation and established itself as an alien species. In parts of California whwere the climate is similar to that of the Mediterranean it has been so successful that it has become an invasive species.

Its scientific name is Cistus monspeliensis which means the Montpellier cistus which is actually an alternative name for this plant especially in gardening circles.

The plant is well adapted for the Mediterranean climate. It grows in the form of a low bush with thick, hairy, glandular leaves which exude a sticky liquid. These characteristics help the plant to conserve water during the long hot summer season when very little if any rain falls. 

Between April and May the bushes are covered in a large number of beautiful white flowers.
The rockrose (or cistus) family to which this plant belongs is composed of about 20 species. In some species the leaves produce a highly aromatic resin known as labdanum.

This sticky liquid has long been used in herbal medicine and as an ingredient in perfumery. In some countries an infusion of the leaves is used to treat diarrhoea.

The resin is extracted by boiling the leaves of a particular species or by dissolving it in a solvent. An essential oil is obtained by steam distillation. The use of labdanum has replaced ambergris which used to be obtained from the sperm whale, an endangered species which is now protected.

It was believed that in ancient times labdanum was one of the ingredients of holy incense which was mentioned in the Old Testament.

This article was published in The Times of Malta on 17 April 2014.

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