The rock roses (Cistus) form a genus of plants in the rock rose family (Cistaceae).
Vegetative characteristics
The cistus species are highly branched, bushy shrubs or dwarf shrubs with aromatic resin, the labdanum. The opposite leaves are sessile or stalked. The leaf blades are simple. Stipules are missing.
Generative characteristics
The terminal or lateral inflorescences are zymose, trugdoldig or wrap-like, occasionally also reduced to a flower.
The hermaphrodite flowers are radially symmetrical and five-fold. The two outer sepals are at least as large as the three inner ones or are absent. The short-lived petals are already wrinkled in the bud. The petals are white, pink to purple in color; in some species they are spotted yellow or dark red at the base. The 50 to 200 stamens are arranged in several rows and all fertile. Usually five, rarely six to twelve carpels are fused into a five-, rarely six to twelve-fold ovary. The ovules are orthotropic.
The woody capsule fruits almost completely open up along the fan walls. The numerous seeds are polygonal.
Occurrence
The genus is distributed throughout the Mediterranean and the Canary Islands. The greatest biodiversity is in the western Mediterranean area (France, Spain, Portugal, Morocco, Algeria). The rock roses are a major part of the garigue. They grow on dry, stony surfaces, often on soils that are poor in lime and nutrients.
Use
Some cultivated forms are used as ornamental plants in Mediterranean parks and gardens.
The resin labdanum can be obtained from the branches and leaves of some species (such as Cistus salviifolius or Cistus ladanifer). For this purpose, goats were herded through Cistus herds on some Greek islands. The sticky secretion stuck to the goatskin. The cut hair was placed in boiling water. After cooling, the resin could be separated off.
Extracts from the gray-haired rock rose (Cistus creticus) are used health-related; in Greece it is drunk as a herbal tea. Throat lozenges (lozenges) are also available. In cell cultures under laboratory conditions, cistus extract has been found to be effective against SARS-CoV-2 (the virus that causes COVID-19) and certain subtypes of the influenza A virus (H5N1 and H1N1v); clinical studies on patients are currently available (As of January 2021) but not yet.
Carl von Linné took the view that the biblical “Rose of Sharon” was a type of rockrose.
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